bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular requirements for thyrotropin enhancement of in vitro antibody production.
Authors: Kruger T E , Blalock J E
Published: December 2022

We reported previously that thyrotropin (TSH) enhanced the in vitro antibody response to a T cell-dependent antigen, sheep red blood cells (SRBC), as determined by direct plaque-forming cell (PFC) assay. The present studies were designed to determine the possible immunoregulatory function of TSH on lymphocytes immunized with the T-independent antigen Brucella abortus-TNP (BA-TNP) and the cellular components involved in such function. We report here that TSH enhanced the in vitro antibody response to BA-TNP as determined by direct PFC assays. Cell depletion studies showed that the TSH effect, although independent of macrophages, required the presence of T cells. Thus, pituitary--and possibly leukocyte--TSH appears to function as a lymphokine which may act via T cells to augment antibody production.
T cell clones specific for IgG2a of the a allotype: direct evidence for presentation of endogenous antigen.
Authors: Bikoff E , Birshtein B K
Published: December 2022

T cell clones specific for IgG2a of the alpha allotype have been isolated from C57BL/6J mice. Antigenic determinants recognized by these clones were localized by using a panel of hybrid IgG2b-IgG2a myeloma proteins. These experiments provide evidence for two distinct antigenic sites, one located in a segment encompassing the hinge region and most of the CH2 domain, and the other in a segment spanning the CH3 domain and the C-terminal eight residues of the CH2 domain. As judged by their failure to respond in the presence of B6.C-H-2bm12 spleen cells, all the clones recognize determinants created, in part, by the I-A beta chain. A strong proliferative response was observed in the presence of spleen cells from several H-2b strains, including C3H.SW, A.BY, D1.LP, and BALB.B. Experiments testing reactivity directed toward spleen cells from appropriate allotype-congenic mouse strains demonstrated that this response was controlled by Igh-linked genes. These results clearly indicated 1) that Igh-1a-specific T cell clones are stimulated by endogenously synthesized IgG2a, and 2) these T cells recognize shared determinants expressed on IgG2a molecules of various strains. These experiments thus provide strong evidence for presentation of self antigens under normal physiological conditions.
Reversible activation of the neutrophil superoxide generating system by hexachlorocyclohexane: correlation with effects on a subcellular superoxide-generating fraction.
Authors: English D , Schell M , Siakotos A , Gabig T G
Published: December 2022

gamma-Hexachlorocyclohexane was found to exert profound effects on the phosphatidylinositol cycle, cytosolic calcium level, and the respiratory burst of human neutrophils. Exposure of neutrophils prelabelled with 32P to 4 X 10(-4) M gamma-hexachlorocyclohexane almost tripled radioactivity in phosphatidic acid and correspondingly decreased radioactivity in phosphatidylinositol 4,5 bisphosphate. Under similar conditions, gamma-hexachlorocyclohexane evoked the generation of superoxide at a rate of over 11 nmol/min/10(6) cells and more than doubled cytosolic-free calcium concentration as monitored by Quin-2 fluorescence. Because intermediates of the phosphatidylinositol cycle, via increases in available calcium levels or activated protein kinase C, are considered potential second messengers for activation of the NADPH-dependent O-2-generating system, we compared neutrophil responses to gamma-hexachlorocyclohexane with responses to phorbol myristate acetate, an activator of protein kinase C with well known effects on neutrophils. Like phorbol myristate acetate, gamma-hexachlorocyclohexane induced neutrophil degranulation but was not an effective chemotactic stimulus. The ability of gamma-hexachlorocyclohexane to induce a pattern of oxidative activation in neutrophil cytoplasts similar to that in intact cells indicated that concurrent degranulation was not required for sustained O-2 generation in response to this agent. When neutrophils or neutrophil cytoplasts exposed to gamma-hexachlorocyclohexane were centrifuged and resuspended in stimulus-free medium, O-2 generation ceased entirely but could be reinitiated by addition of the same stimulus. This finding was in contrast to the continued O-2 production by phorbol myristate acetate-stimulated neutrophils similarly washed and resuspended in stimulus-free medium. Unlike subcellular fractions of phorbol myristate acetate-stimulated neutrophils, corresponding fractions prepared from gamma-hexachlorocyclohexane-stimulated neutrophils contained almost no detectable NADPH-dependent O-2-generating activity. Subcellular oxidase activity was not recovered when cells and membrane fractions were continuously exposed to gamma-hexachlorocyclohexane during disruption and fractionation after cell stimulation, nor could it be induced by the addition of the stimulus to the subcellular fractions. Thus, the stimulus dependence of continuous neutrophil superoxide release evoked by gamma-hexachlorocyclohexane does not merely reflect a physical interaction of the agonist with the enzyme system involved.(ABSTRACT TRUNCATED AT 400 WORDS)
A specific antagonist of platelet-activating factor suppresses oedema formation in an Arthus reaction but not oedema induced by leukocyte chemoattractants in rabbit skin.
Authors: Hellewell P G , Williams T J
Published: December 2022

The properties of a novel platelet-activating factor (PAF) antagonist, L-652731, on oedema responses in rabbit skin induced by exogenous inflammatory mediators and by mediators generated endogenously in a reversed passive Arthus reaction have been investigated. Oedema responses in the skin were measured by using the local accumulation of i.v. injected 125I-albumin. The antagonist, mixed with mediators before intradermal injection, caused a dose-dependent suppression of oedema responses to PAF. In contrast, responses induced by other directly acting mediators (bradykinin and histamine) and responses induced by PMN leukocyte-dependent mediators (C5a des Arg, N-formyl-methionyl-leucyl-phenylalanine, and leukotriene B4) were not suppressed. Thus, a secondary release of PAF does not appear to be involved in mediating the actions of these agents. In a reversed passive Arthus reaction, intradermal injection of L-652731 together with antibody resulted in a significant inhibition of the oedema formation measured for 2 hr after i.v. antigen challenge. In contrast, oedema responses induced by intradermal injection of preformed immune complexes were not affected by the antagonist. These results suggest that the endogenous production of PAF, in close proximity to microvascular endothelial cells, appears to be an important step in the development of an Arthus reaction. The cellular source of PAF is unknown, but one possibility is the PMN leukocyte, which releases PAF during phagocytosis of immune complexes.
Germ-line sequence of the DH segment employed in Ars-A antibodies: implications for the generation of junctional diversity.
Authors: Landolfi N F , Capra J D , Tucker P W
Published: December 2022

The majority of antibodies produced by A/J mice in response to p-azophenylarsonate belong to the Ars-A family. These antibodies have the conserved sequence cys-ala-arg-ser-x-tyr-tyr (in which x is variable) spanning the V-D junction of the heavy chain. The cys-ala-arg residues are accounted for in the sequence of the A/J VH gene; the tyr-tyr are believed to be specified by the A/J DH segment, although this assumption is based on the DFL16.1 sequence derived from BALB/c mice. This implies that the ser-x is generated by joining imprecision and/or N segment addition. More recent data have revealed that the codon specifying the junctional serine residue is highly conserved (TCN, where N is usually G), suggesting a germline origin. Because there is no obvious way to generate this codon from the A/J Ars-A VH gene, we examined the involvement of the A/J DH segment in the generation of this junctional residue by cloning and sequencing the A/J equivalent to DFL16.1. We have established that this DH segment is polymorphic among BALB/c and A/J at the nucleic acid sequence level, and that it does not encode the junctional serine. This implies that a mechanism other than joining imprecision or random N segment addition operates at V-D junctions of Ars-A heavy chains.
Molecular analysis of the rat MHC. I. Delineation of the major regions in the MHC and in the grc.
Authors: Hassett A L , Stranick K S , Locker J , Kunz H W , Gill T J
Published: December 2022

Southern blot analysis with liver DNA from a unique series of recombinant (R10, R11, R16, R18, R21, and R22), congenic (Y0.1U.grc+, Y0.1U.grc+/Y0.1L.grc, and Y0.1L.grc) and inbred rats has been performed to examine the restriction fragment length polymorphisms of class I genes. After digestion with Xba I or Eco RI, the genomic DNA was resolved on agarose gels, was transferred to nitrocellulose membranes, and was hybridized with murine H-2 cDNA probes. Eighteen to 25 bands of varying intensities could be clearly resolved in any given strain. Analysis of these hybridization patterns detected restriction fragment length polymorphisms that permitted the assignment of 17 specific fragments to regions within the major histocompatibility complex: RT1.A, RT1.B/D, and the RT1.E-grc-T1 alpha region. Fragments have been identified that are specific for grc, grc+, and RT1.E, and mark the junction sites between these loci. In addition, several markers identify the region around the sites of recombination in some strains. The hybridization pattern of the R18 recombinant had a unique band that specified a point of recombination within the grc. The recombinant R11 presented a unique restriction pattern unrelated to either of the parental strains or other related strains. This result suggests that R11 arose from a recombination event(s) undetected by conventional serologic methods.
Mononuclear phagocyte system in SLE. II. A kinetic model of immune complex handling in systemic lupus erythematosus.
Authors: Meryhew N L , Kimberly R P , Messner R P , Runquist O A
Published: December 2022

Using the principles of reaction kinetics, we constructed a model for the handling of immune complexes and the pathogenesis of SLE immune complex disease. The model incorporates rate constants for complement- and Fc-mediated clearance, parameters for autoantibody, complement and immune complex levels, and scores for clinical disease activity. The model assumes that complement fixation by immune complexes is a prerequisite for complement-mediated clearance and that disease activity results from immune complex deposition. To test the relationships derived, data from 32 lupus patients were analyzed and the predictions were compared with actual findings. The model predicts a low correlation coefficient between disease activity and immune complex levels (found, r = 0.25, p greater than 0.1). The model also predicts a poor correlation between disease activity and impaired Fc-mediated clearance in patients with normal complement levels (found, r = 0.10, p greater than 0.1), but a high correlation coefficient between disease activity and impaired Fc-mediated clearance in patients with hypocomplementemia (found, r = 0.61, p less than 0.001). In patients with normal complement levels, the model predicts a good correlation between anti-DNA antibody and immune complex levels (found, r = 0.71, p less than 0.001), whereas hypocomplementemic patients should have a good correlation between anti-DNA to CH50 ratios and immune complex levels (found, r = 0.73, p less than 0.001). The model predicts that disease activity should correlate better with the product of the anti-DNA to CH50 ratio and the rate constant for Fc-mediated clearance than with any single parameter (found, r = 0.85, p less than 0.0001). These significant correlations, which were predicted by the model, suggest that complement-mediated mechanisms are the first line of host defense against immune complex-induced injury, that the efficiency of complement opsonization plays a central role, and that both abnormal complement- and Fc-receptor function leads to active renal disease in SLE.
Recognition of MHC class I allodeterminants regulates the generation of MHC class II-specific CTL.
Authors: McCarthy S A , Singer A
Published: December 2022

We have analyzed the signals influencing the generation of major histocompatibility complex (MHC) class II allospecific cytolytic T lymphocytes (CTL) and have found that the development of these CTL is actively regulated in primary in vitro cultures by Lyt-2+ T cells triggered in response to MHC class I alloantigens. Class II allospecific CTL can be readily stimulated in primary cultures, but the presence of a simultaneous class I MHC stimulus in these cultures causes a marked reduction of class II-specific CTL activation. This reduction can be prevented by adding to culture a dose of monoclonal anti-Lyt-2 antibody (in the absence of complement) that does not block the generation of class I-specific CTL. The role of MHC class I alloantigens in the regulation of class II allospecific responses illustrates that T cells recognizing class I and class II MHC antigens in mixed leukocyte cultures interact in a complex and nonreciprocal manner to influence the final effector T cell repertoire elicited by this complex immunogenic challenge.
Monoclonal antibodies, L-35 and L-36, define novel T cell activation antigens.
Authors: Maino V C , Janszen M E
Published: December 2022

Two novel T cell specific activation antigens were characterized and were defined by monoclonal antibodies developed against mitogen-stimulated human T cells. These antigens, designated as L-35 and L-36 were expressed on both the CD 4(Leu-3) and the CD 8(Leu-2) subsets of activated but not resting T cells. Moreover these antigens were not expressed on a number of T, B, and myeloid tumor cell lines. L-35 and L-36 were expressed on interleukin 2 (IL 2)-dependent cloned T cell lines, and were weakly expressed on the T cell tumor line, HSB-2. L-35 was expressed on granulocytes and a small subset of thymocytes. SDS-PAGE analysis of 125I-labeled lysates from phytohemagglutinin (PHA)-activated T cells demonstrated that L-35 existed as a complex of 32,000 and 97,000 dalton polypeptides under reducing and nonreducing conditions. Anti-L-36 immunoprecipitated a 90,000 dalton structure from PHA-activated cell lysates prepared with CHAPS detergent. When immunoprecipitates were analyzed from [35S]methionine labeled lysates, anti-L-35 precipitated only the 97,000 dalton component, suggesting that the 32,000 dalton subunit of L-35 complex was not synthesized by the activated cell population. Furthermore anti-L-35 did not immunoprecipitate a 32,000 dalton component from 125I-labeled lysates of anti-Leu-4 or Con A-activated cells, suggesting that the 32,000 dalton component of the L-35 complex may represent a subunit of PHA. The 32,000 dalton protein could not, however, be precipitated from cells incubated with PHA for less than 1 day. These results suggested that anti-L-35 recognizes a 97,000 dalton structure expressed on activated T cells, and that upon activation by PHA, becomes associated with a subunit of this mitogen.
Effect of interferon-alpha on immunoglobulin synthesis by human B cells.
Authors: Peters M , Ambrus J L , Zheleznyak A , Walling D , Hoofnagle J H
Published: December 2022

We have investigated the effect of human recombinant interferon-alpha (IFN-alpha) on mitogen-induced immunoglobulin (Ig) production by peripheral blood mononuclear cells from normal individuals. Low concentrations (1 to 100 IU/ml) of IFN-alpha enhanced pokeweed mitogen-stimulated Ig production. In contrast, high concentrations of IFN-alpha (10(5) IU/ml) suppressed pokeweed mitogen-induced Ig production. Irradiation of T cells did not ablate the high dose suppression, indicating that suppression was not due to a radiation-sensitive T cell. Kinetic experiments revealed that IFN-alpha needed to be added to 10 day cultures within the first 72 hr for either enhancement or suppression to be noted. Preincubation of purified B cells with IFN-alpha suppressed Ig production as completely as when unfractionated mononuclear cells were incubated with IFN-alpha. On the other hand, preincubation of T cells or monocytes with IFN-alpha had no effect on subsequent Ig production in reconstituted mononuclear cell cultures. Mitogen-induced proliferation of purified B cells was not affected by IFN-alpha at any concentration, but Ig production by purified B cells stimulated with Staphylococcus aureus Cowan I or anti-mu and B cell differentiation factors responded to IFN-alpha with low concentration enhancement and high concentration suppression. Studies of Ebstein-Barr virus-transformed B cell lines showed that IFN-alpha caused a similar effect on the CESS line as on peripheral blood B cells, with low dose enhancement and high dose suppression of Ig production. Thus one IFN-alpha effect is to modulate Ig production, and this appears to be a direct effect on B cells. Combined with the data in the accompanying paper, the effects of IFN-alpha on B cell function are similar in vivo and in vitro.
Demonstration that human B cells respond differently to interleukin 2 and B cell differentiation factor based on their stages of maturation.
Authors: Nakagawa T , Nakagawa N , Goldstein H , Volkman D J , Fauci A S
Published: December 2022

The mechanisms whereby interleukin 2 (IL 2), interferon-gamma (IFN-gamma), and B cell differentiation factor (BCDF) alone or in combination modulate human B cell differentiation are currently under intensive study. To dissect out the effects of individual lymphokines contained in mixed lymphocyte reaction-culture supernatants (MLR-CS) on B cell differentiation, we employed pure factors that possessed the same activity as factors contained in MLR-CS (IL 2: 50 U/ml, IFN-gamma: 7 U/ml, BCDF-Nal: 5 pM/ml, BCDF-YA2: 12.5% v/v) singly and in combination to human B cells. By activating purified human B cells with Staphylococcus aureus Cowan I (SAC) for 3 days, separating B blast cells by the Percoll centrifugation method, and then either using these B blast cells as B cells in the earlier stage after SAC-activation, or further culturing these B blast cells for 4 more days without any stimuli and using these B cells as B cells in the later stage after SAC-activation, we could define two different populations of cells. Disparity in the populations could be demonstrated by the observation that B cells in the earlier stage were 81.2% Tac-antigen+, 23.2% B2+, 68.9% transferrin receptor+, and 90.5% HLR-DR+, whereas B cells in the later stage were observed to be less positive for each surface antigen: 36.1% Tac-Ag+, 8.3% B2+, 45.3% transferrin receptor+, and 58.7% HLR-DR+. By adding each factor to both B cell fractions, we also demonstrated functional differences in the two populations. B cells in the earlier stage of activation only differentiated in response to IL 2 or IL 2 + IFN-gamma but not to BCDF, which was in contrast to B cells in the later stage that did not differentiate in response to IL 2 but did differentiate to BCDF. However, B cells in both stages proliferated in response to IL 2 but not to BCDF. Finally, we separated B cells in the later stage into two populations by the Percoll discontinuous gradient centrifugation. Lower density (larger) B cells were observed to proliferate but not to differentiate in response to IL 2, whereas higher density (smaller) B cells were observed to differentiate in response to BCDF. Therefore, we conclude that activated B cells initially become large and gain Tac-Ag and differentiate in response to IL 2 alone as well as the combination of IL 2 and IFN-gamma, whereas later in the more mature stage they become smaller again and differentiate into Ig-secreting cells only in response to BCDF.
Prostaglandins posttranscriptionally inhibit monocyte expression of interleukin 1 activity by increasing intracellular cyclic adenosine monophosphate.
Authors: Knudsen P J , Dinarello C A , Strom T B
Published: December 2022

The effect of prostaglandins and cyclic 3',5'-adenosine monophosphate (cAMP) on expression of human interleukin 1 (IL 1) activity was investigated in the promonocytic tumor cell line U937 and peripheral blood monocytes. After in vitro stimulation by bacteriotoxins, monocytes express IL 1 activity, as measured by the thymocyte costimulation assay. Although high doses of bacteriotoxins impaired expression of IL 1, this effect was reversed by indomethacin. When stimulated monocytes were cultured with exogenous prostaglandins, including PGE2 and PGI2, expression of IL 1 was reversibly inhibited. Interaction of U937 cells with PGE2 resulted in a transient increase in cellular cAMP concentration during the first hour of exposure. Other agents that cause an increase in levels of cellular cAMP, including theophylline, isobutylmethylxanthine, dibutyryl cAMP, or cholera toxin, also reversibly reduced expression of IL 1 by stimulated monocytes. The effect of these agents on levels of IL 1 mRNA was analyzed. TSS-stimulated increase in levels of IL 1-encoding mRNA was studied both by DNA-RNA hybridization analysis performed with an IL 1-beta cDNA probe and by injecting U937 polyadenylated mRNA into frog oocytes and then measuring expression of IL 1 activity in the oocyte supernatant. Agents that increased levels of cellular cAMP did not alter levels of IL 1 mRNA accumulation or global protein synthesis in TSS-stimulated U937 cells. IL 1 stimulates synthesis of prostaglandins that reach high levels during immune and inflammatory reactions. Our data suggest that prostaglandins participate in an autoregulatory pathway that posttranscriptionally reduces expression of IL 1 activity.
The effects of adenosine agonists on human neutrophil function.
Authors: Schrier D J , Imre K M
Published: December 2022

Adenosine is a potent physiologic substance with a variety of biologic activities. Many of the effects of adenosine appear to be mediated by two populations of cell-surface adenosine receptors (A1 and A2). We have examined the effects of several adenosine receptor agonists on human neutrophils stimulated with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). The results indicate that both superoxide anion generation and degranulation (as assessed by lysozyme release) are inhibited. Inhibition correlated most strongly with A2 receptor affinity for both parameters and was reversible by the adenosine receptor antagonist 8-phenyltheophylline. Because toxic oxygen metabolites and degradative enzymes are implicated in a variety of inflammatory disorders, adenosine agonists may be useful probes to help expand our knowledge of the role of these mediators in human disease.
Two roles for Ia in antigen-specific T lymphocyte activation.
Authors: Kim K H , Shivdasani R A , Thomas D W
Published: December 2022

In this study we examined the mechanism by which a PPD-specific murine T cell hybridoma, 8B2, recognized PPD associated with antigen-presenting cells (APC) in a manner genetically restricted by I-Ad. It was found that PPD-pulsed APC that were glutaraldehyde-fixed and treated with anti-Ia monoclonal antibody (abbreviated as PGM) were unable to stimulate the 8B2 T cells, as expected, due to inhibition caused by antibody binding to the Ia. However, addition of non-antigen-treated, glutaraldehyde-fixed APC (abbreviated as G) to cultures containing 8B2 T cells and PGM restored T cell activation, as determined by IL 2 production. This second non-antigen-specific function provided by the additional APC, G, was attributed to Ia and could be substituted by APC plasma membranes and by soluble membrane extracts. Genetic restriction analysis in which a variety of Ia-positive and Ia-negative cell lines and B cell blasts from different mouse strains were used as PGM or as G showed that each APC provided different Ia determinants that were specifically recognized by the T cells. PGM cells had to express I-Ad in order to present the PPD determinant, whereas the non-antigen-specific function was specific for I-Ad or I-Ab. These results suggest that the anti-Ia antibody does not interfere with the PPD/I-Ad-specific determinant bound by the antigen-specific T cell receptor, but prevents a second non-antigen-specific interaction with another region of the Ia molecule, which is provided by G. These two roles for Ia (antigen-specific and non-antigen-specific) were also found for activation of normal polyclonal PPD-specific T cell responses; thus they are not unique to the 8B2 T cell, but are generally applicable. In addition, T cell interactions with PGM and with G each provide different intracellular activation signals. This was determined by substituting the PGM or the G with either the tumor promoter phorbol 12-myristate 13-acetate (PMA) or the Ca++ ionophore, ionomycin. It was found that 8B2 T cells cultured with PGM and ionomycin, but not with PGM and PMA, were activated for IL 2 production. Neither PMA nor ionomycin in conjunction with G resulted in T cell activation. Taken together, these results indicate that 8B2 T cell activation involves APC Ia antigens in two different ways: one is to contribute to the presentation of the foreign PPD antigen, and a second is a non-antigen-specific Ia-T cell interaction necessary to provide additional intracellular activation signals.(ABSTRACT TRUNCATED AT 400 WORDS)
Administration of F(ab')2 fragments of monoclonal antibody to L3T4 inhibits humoral immunity in mice without depleting L3T4+ cells.
Authors: Gutstein N L , Wofsy D
Published: December 2022

Treatment of mice with monoclonal antibody (MAb) to L3T4 blocks the humoral immune response to antigens administered when L3T4+ cells are depleted. To determine whether depletion of target cells is required to suppress immunity, we examined the effect of treatment with F(ab')2 fragments of anti-L3T4 on the response of BALB/c mice to immunization with bovine serum albumin (BSA) in complete Freund's adjuvant. Treatment with F(ab')2 fragments of anti-L3T4 every 2 days (1 mg i.p.) beginning at the time of immunization significantly inhibited production of anti-BSA antibodies without depleting target cells. A single injection of anti-L3T4 fragments at the time of immunization also significantly inhibited production of anti-BSA antibodies, but was not as effective as repeated administration of the MAb fragments (75% inhibition compared with 98% inhibition; p less than 0.05). Moreover, one injection of anti-L3T4 fragments stimulated a host immune response to the rat MAb, whereas sustained therapy with the anti-L3T4 fragments blocked this response. Surprisingly, low doses (less than or equal to 10 micrograms/mouse) of intact rat MAb to L3T4 also stimulated a host immune response to the MAb but, as previously reported, higher doses of intact MAb to L3T4 did not. These findings establish that depletion of L3T4+ cells is not required to suppress immunity with MAb to L3T4. They also indicate that the ability of rat MAb to L3T4 to block the immune response to itself is dose dependent. Because the L3T4 antigen in mice is homologous to the CD4 antigen in humans, our findings have implications regarding the potential use of MAb to CD4 in humans.
The effects of polyinosinic:polycytidylic acid (pI:C) on the graft-vs-host (GVH) reaction. II. Increased NK-mediated rejection on C57BL/6 lymphocytes by (C57BL/6 X A)F1 mice.
Authors: Peres A , Nestel F P , Seemayer T A , Lapp W S
Published: December 2022

We previously demonstrated that treatment of (C57BL/6 X A)F1 (F1) recipient mice with polyinosinic:polycytidylic acid (pI:C) before injection with 30 X 10(6) C57BL/6 (B6) lymphocytes prevents both the immunosuppression and pathologic lesions typical of graft-vs-host (GVH) reactions. We now report the further characterization of this phenomenon. Donor spleen and lymph node cells were labeled with fluorescein in vitro and injected into pI:C-treated or untreated mice. Two days later, recipient splenocytes were analyzed for the presence of fluorescein-labeled donor cells by flow microfluorometry. Treatment of F1 mice with pI:C resulted in a sharp reduction in the recovery of labeled B6 but not A strain parental cells. Treatment with pI:C had no effect when syngeneic recipients were used, or when F1 cells were injected into A, B6, or F1 recipients. These results suggest that pI:C treatment induces rejection of B6 but not A or F1 lymphocytes by F1 hybrid mice at least as early as 2 days after donor cell transfer. As F1 cells are not rejected by either parent, rejection does not seem to be directed against classical alloantigens. These observations are compatible with the previously described model of hybrid resistance (HR) against bone marrow grafts. The rapidity of rejection strongly suggested that natural cytotoxic mechanisms were involved, thus, natural killer (NK) cell and macrophage (M phi) cytotoxic activities were tested throughout the time when the parental cell graft was being rejected. Over this period, pI:C treatment increased cytotoxic activity against the NK-sensitive target cell line YAC-1 but had no effect on spontaneous M phi tumoricidal activity against the L5178Y and MDAY-D2 cell lines. The results suggest that NK cells, but not M phi, may be involved in the elimination of B6 parental cells by the pI:C-treated F1 mice. NK cells have been demonstrated to be radioresistant; thus, as a test of our hypothesis, we examined the effects of irradiation on the capacity of pI:C treated F1 mice to reject B6 lymphocytes. The results show that this capacity was not blocked by 750 cGy, a dose of radiation that abrogates most T and B cell functions. Furthermore, rejection of parental cells could be prevented by treatment of recipient F1 mice with antibodies to asialo GM1, a treatment that suppresses NK activity. These data demonstrate that pI:C-mediated protection from GVH-induced changes is due to increased rejection of grafted B6 parental cells by F1 NK cells, a phenomenon very similar, if not identical, to HR to bone marrow grafts.
Interaction between myelin basic protein-sensitized T lymphocytes and murine cerebral vascular endothelial cells.
Authors: McCarron R M , Spatz M , Kempski O , Hogan R N , Muehl L , McFarlin D E
Published: December 2022

Lymph node cells from SJL mice immunized with guinea pig myelin basic protein proliferate in vitro to the same antigen. This proliferative response is abolished by depletion of macrophages-monocytes, but can be reconstituted by the addition of cerebral vascular endothelial cells (EC) freshly isolated from syngeneic mice with adoptively transferred acute experimental allergic encephalomyelitis (EAE). Reconstitution by EC from mice with EAE can be blocked by pretreatment of EC with syngeneic anti-I-A antisera. Freshly isolated EC from normal syngeneic mice do not restore responsiveness, but can be induced to present antigen by culture with murine recombinant immune interferon-gamma or supernatants from a variety of immune cell cultures. These findings are consistent with the hypothesis that immune cells release interferon and/or other soluble factors which induce I-A molecules on EC, which subsequently acquire the capacity to present antigen. The implications of these findings relate to the migration of cells across the blood-brain-barrier into the central nervous system, and are of importance in the understanding of the pathogenesis of several neurologic disorders.
Prazosin treatment during the effector stage of disease suppresses experimental autoimmune encephalomyelitis in the Lewis rat.
Authors: Brosnan C F , Sacks H J , Goldschmidt R C , Goldmuntz E A , Norton W T
Published: December 2022

As part of a study on the role of vasoactive amines in experimental autoimmune encephalomyelitis (EAE), we have found that treatment beginning 7 days post-inoculation (dpi) with the specific alpha 1-adrenoceptor antagonist prazosin can significantly suppress clinical signs of disease in the Lewis rat. In this paper we have addressed the effect of treatment with prazosin commencing at varying times in the disease process. The results show that treatment during the early inductive stage (1 to 6 dpi) has no effect on the clinical course of the disease, whereas treatment commencing at the time of onset of early clinical signs (10 to 16 dpi) still significantly suppresses EAE. Leakage of serum proteins into the central nervous system (CNS) and histologic expression of EAE are also suppressed. Prazosin had no effect on lymphocyte responses to mitogen or antigen as determined by lymphocyte transformation tests when lymphocytes were exposed to prazosin in vitro, and the responses of lymphocytes from prazosin-treated animals were similar to those from saline-treated animals. These results support the hypothesis that prazosin suppresses EAE through a direct vascular effect although they do not preclude an immunologic component to its mechanism of action.
Patients with Wiskott-Aldrich syndrome have normal IgG2 levels.
Authors: Nahm M H , Blaese R M , Crain M J , Briles D E
Published: December 2022

The Wiskott-Aldrich Syndrome (WAS) in humans has a number of similarities to the immunodeficiencies found in CBA/N mice, including X-chromosome-linked inheritance, inability to produce antibodies to various carbohydrate antigens, susceptibility to various bacterial infections, and an imbalance in B lymphocyte subpopulations. Moreover, in both man and mice, IgG antibodies to polysaccharides are predominantly, but not exclusively, restricted to a single IgG subclass--IgG2 in man, and IgG3 in the mouse. Because CBA/N mice have a deficiency of IgG3 antibodies and because human IgG2 subclass deficiencies have been generally associated with inability to produce antibodies to carbohydrate antigens, it would seem likely that patients with WAS would have greatly reduced levels of IgG2. Quite to the contrary, the data presented here demonstrate that WAS patients have normal levels of the different IgG subclasses, including IgG2. Thus, inability to produce antibodies to carbohydrates is not always associated with IgG2 subclass deficiency.
Expression of specific binding sites on Candida with functional and antigenic characteristics of human complement receptors.
Authors: Edwards J E , Gaither T A , O'Shea J J , Rotrosen D , Lawley T J , Wright S A , Frank M M , Green I
Published: December 2022

Receptors for C3 degradation fragments (CR1, CR2, and CR3) are present on many human cells including phagocytes and lymphoid cells and may be critical in the attachment of invading microorganisms. In these studies Candida were found to mimic the human CR by binding erythrocytes coated with specific human C3 fragments. Yeast forms of Candida species were adhered to glass slides and were allowed to germinate. Sheep erythrocytes (E) were coated with IgM (EA) and human complement components to prepare EA, EAC14, EAC3b, EAC3bi, and EAC3d. These test cells were then examined for adherence to the organism. Antibodies to human CR1, CR2, and CR3 were used to evaluate their potential for blocking adherence of the test erythrocytes to Candida. Fluorescein-labeled antibodies to human complement receptors were also used to characterize the binding sites. EAC3bi and EAC3d, but not E, EA, or EAC14, bound extensively to the germ tubes and pseudohyphae of Candida albicans and C. stellatoidea. EAC3b bound infrequently. Other Candida species, generally considered less pathogenic, bound significantly fewer specific test erythrocytes than C. albicans. Monoclonal antibodies to human CR1 and CR3 (3D9, 1B4, C511, 2B6, anti-B2, Mo1, and anti-Mac-1), in general, did not block adherence of test erythrocytes. Blocking of adherence of EAC3bi and EAC3d test erythrocytes coated with small quantities of C3 fragments occurred with high concentrations of monoclonal (anti-CR2) HB-5 and polyclonal (anti-CR2) anti-GP 140. Immunofluorescence studies demonstrated binding of Mo-1 to the germinated forms of the organism, whereas binding of the other antibodies was not seen. These studies suggest a surface constituent on the organism similar to CR on human cells. Additional studies are necessary to further define the molecular nature of the binding site. The ability of organisms to mimic human CR may be more generalized than previously known and may serve as a mechanism for modification of the inflammatory and immune response.
Biosynthetic human GM-CSF modulates the number and affinity of neutrophil f-Met-Leu-Phe receptors.
Authors: Weisbart R H , Golde D W , Gasson J C
Published: December 2022

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) modulates the function of mature neutrophils by priming for enhanced chemotaxis and oxidative metabolism in response to N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe). Our studies establish a relationship between f-Met-Leu-Phe receptor number and affinity and neutrophil chemotaxis and oxidative metabolism. A brief (5- to 15-min) exposure to physiologic concentrations of GM-CSF (10 pM to 100 pM) enhances f-Met-Leu-Phe-induced neutrophil chemotaxis by 85%, correlating with a rapid threefold increase (46,000/cell to 150,000/cell) in high-affinity neutrophil f-Met-Leu-Phe receptors. More prolonged incubation (1 to 2 hr) of neutrophils with GM-CSF is accompanied by a change to low-affinity f-Met-Leu-Phe receptors (Kd = 29 nM to Kd = 99 nM) concomitant with priming for enhanced neutrophil oxidative metabolism. Moreover, enhanced chemotactic responses to f-Met-Leu-Phe are no longer evident after more prolonged incubation of neutrophils with GM-CSF. These results show that a single lymphokine (GM-CSF) induces sequential changes in neutrophil f-Met-Leu-Phe receptor number and affinity that may enhance different physiologic responses.
Passive transfer of Leishmania lipopolysaccharide confers parasite survival in macrophages.
Authors: Handman E , Schnur L F , Spithill T W , Mitchell G F
Published: December 2022

Infection of macrophages by the intracellular protozoan parasite Leishmania involves specific attachment to the host membrane, followed by phagocytosis and intracellular survival and growth. Two parasite molecules have been implicated in the attachment event: Leishmania lipopolysaccharide (L-LPS) and a glycoprotein (gp63). This study was designed to clarify the role of L-LPS in infection and the stage in the process of infection at which it operates. We have recently identified a Leishmania major strain (LRC-L119) which lacks the L-LPS molecule and is not infective for hamsters or mice. This parasite was isolated from a gerbil in Kenya and was identified phenotypically as L. major by isoenzyme and fatty acid analysis. In this study we have confirmed at the genotype level that LRC-L119 is L. major by analyzing and comparing the organization of cloned DNA sequences in the genome of different strains of L. major. Here we show that LRC-L119 promastigotes are phagocytosed rapidly by macrophages in vitro, but in contrast to virulent strains of L. major, they are then killed over a period of 18 hr. In addition, we show that transfer of purified L-LPS from a virulent clone of L. major (V121) into LRC-L119 promastigotes confers on them the ability to survive in macrophages in vitro.
The primary structure of HLA-A32 suggests a region involved in formation of the Bw4/Bw6 epitopes.
Authors: Wan A M , Ennis P , Parham P , Holmes N
Published: December 2022

All HLA-B locus molecules have either the Bw4 or Bw6 epitopes. In addition, the Bw4 epitope is found on HLA-Aw23, Aw24, and A32, and Bw6 is also found on HLA-Cw3. The structural basis for these determinants and the evolution of their distribution among products of the HLA-B locus has been a long standing puzzle. To identify residues that may be involved in these determinants, we have cloned a gene for A32 and sequenced the protein encoding exons. Comparison of the predicted protein sequence with other HLA-A,B,C sequences identified residues 79 through 83 of the alpha 1 domain as having a pattern of polymorphic substitution that correlates with the presence and absence of the Bw4 and Bw6 epitopes.
Characterization of two monoclonal idiotype-binding suppressor T cell factors specific for the antibody response to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT).
Authors: Poon R Y , Kapp J A , Pierce C W , Sorensen C M
Published: December 2022

We have previously identified and described two distinct types of suppressor T cell factors specific for the PFC response to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) or L-glutamic acid50-L-tyrosine50 (GT). Both of these factors are antigen-specific and I-J+. GAT-TsF1 is not MHC-restricted and is composed of a single polypeptide chain, whereas GAT-TsF2 is MHC-restricted and is composed of two different polypeptide chains. We have not previously found evidence for an obligatory, idiotype-specific suppressor T cell in this suppressor pathway. However, we now report that idiotype-specific suppressor T cells can be elicited by exposing normal spleen cells to GAT-TsF1 or GAT-TsF2 in the absence of antigen in vitro. These factor (TsF1/TsF2)-induced cells have been fused with the AKR thymoma, BW5147, and hybridomas were selected for production of suppressor factors that inhibit GAT-specific antibody responses in vitro. In this report, we characterize one monoclonal factor from each fusion. Neither factor binds GAT or the related co-polymer, GT; both factors have binding sites for GAT-specific idiotypes but not for unrelated idiotypes either in the form of antibody immobilized on Sepharose or as cell surface determinants expressed by B cell hybridomas. Moreover, their reactivities for a panel of monoclonal anti-GAT antibodies are overlapping but not identical. Both factors are composed of two polypeptide chains, and both chains are required for suppressive activity; one chain bears the I-J determinant, whereas the other possesses the idiotype-binding activity of the intact molecule. Both idiotype-binding factors are restricted by MHC- and Igh-linked genes, and transcomplementation is observed in the F1 mice between MHC-congenic and Igh-congenic parents. Both factors are active late in Mishell-Dutton cultures. These data support the contention that these two factors are similar but nonidentical members of an anti-idiotypic class of GAT-specific suppressor factors.
A cascade of T-T interactions, mediated by the linked recognition of antigen, in the induction of T cells able to help delayed-type hypersensitivity responses.
Authors: Bretscher P A
Published: December 2022

Previous work has shown that specific helper T cells are required for the primary induction of delayed-type hypersensitivity (DTH). Conditions are defined here under which the primary induction by antigen of precursor helper T cells only occurs in the presence of specific, irradiated effector T cells, demonstrating that the induction of helper T cells requires T-T cooperation. The interaction between precursor and effector helper T cells is mediated by the recognition of epitopes that must be physically linked to one another. In more detail, hapten-Ficoll conjugates and xenogeneic red blood cells induce medium-density but not low-density cultures of unprimed murine spleen cells to express antigen-specific DTH. Low-density cultures do not support the induction of DTH unless they are supplemented with specific irradiated helper T cells. These helper T cells are themselves induced when antigen is added to medium-density but not low-density cultures. Precursor helper T cells in low-density cultures are only induced by antigen in the presence of additional specific irradiated T cells. Further experiments were directed at analyzing the nature of this T-T interaction. Irradiated hapten-primed T cells help the induction of precursor helper T cells specific for burro red blood cells (BRBC) in the presence of haptenated BRBC and chicken red blood cells (CRBC), but do not help in the presence of haptenated CRBC and BRBC. These experiments demonstrate that the interaction between precursor and effector T cells is mediated by the linked recognition of antigen. These findings show that the induction of precursor cells for both DTH reactivity, and those T cells able to help in the induction of DTH, require specific helper T cells. It is further shown that the induction of T cells able to help in the induction of helper precursor cells takes place in medium-density but not low-density cultures. In order words, antigen, when added to medium-density cultures of normal spleen cells, induces T cells able to mediate DTH, and T cells able to help in the induction of these helper T cells, whereas antigen induces none of these T cells when added to low-density cultures unless appropriate specific helper T cells are added.(ABSTRACT TRUNCATED AT 400 WORDS)
Cultured Lyt-2- L3T4- T lymphocytes from normal thymus or lpr mice express a broad spectrum of cytolytic activity.
Authors: Budd R C , Cerottini J C , MacDonald H R
Published: December 2022

T lymphocytes expressing the surface phenotype Lyt-2- L3T4- represent a minor population of immature thymocytes that appear to be the precursors of mature T cells. Cells with the same apparent surface phenotype also accumulate in vast numbers in the lymphoid tissues of the autoimmune lpr mouse. Lyt-2- L3T4- T lymphocytes from lpr lymph node (LN) or normal thymus express low to undetectable levels, respectively, of surface antigen receptor. In addition, they produce reduced amounts of lymphokines compared with normal T cells and lack precursors of alloantigen-specific cytolytic T lymphocytes. We previously showed that after culture with phorbol esters and interleukin 2, lpr Lyt-2- L3T4- T lymphocytes proliferate and differentiate, acquiring increased levels of surface antigen receptor by most cells, as well as Lyt-2 by a portion. We now show that cultured Lyt-2- L3T4- T cells from lpr LN or normal thymus are very efficiently cytolytic toward not only allogeneic tumor targets, but also natural killer (NK)-susceptible targets and syngeneic targets. Such killing was not inhibited by antibodies to H-2 or Lyt-2. In contrast, cultured mature Lyt-2+ L3T4- T cells from normal LN, thymus, or lpr LN were cytolytic only toward allogeneic targets and were dependent on Lyt-2 expression and H-2 recognition. The similarities of cultured Lyt-2- L3T4- T cells to NK and lymphokine-activated killer cells are discussed.
Regulation of human T lymphocyte mitogenesis by antibodies to CD3.
Authors: Davis L , Vida R , Lipsky P E
Published: December 2022

The inhibitory and mitogenic effects of anti-CD3 antibodies (anti-CD3) were examined in cultures of human peripheral blood T cells. Resting T cells required the presence of accessory cells (AC) or phorbol myristate acetate (PMA) to be stimulated by soluble anti-CD3 (OKT3 and 64.1). Anti-CD3 was unable to induce activation of AC-depleted T cells as determined by IL 2 receptor expression, IL 2 production, cell cycle analysis, or detectable DNA synthesis. Although T cell responses to PHA also required AC, far fewer were necessary to generate responses. Anti-CD3 inhibited PHA-stimulated T cell IL 2 production, IL 2 receptor expression and proliferation in partially AC-depleted cultures. Moreover, anti-CD3 was able to inhibit PHA responses when added to culture as late as 24 to 42 hr after the initiation of a 96-hr incubation. Increasing concentrations of PHA reduced the inhibitory effect of anti-CD3 on PHA-stimulated T cell proliferation, whereas IL 2 production remained suppressed. Anti-CD3 linked to Sepharose beads effectively inhibited PHA-stimulated T cell DNA synthesis, indicating that internalization of the CD3 molecule was not required for inhibition of PHA responses. Although inhibition of IL 2 production was a major effect of anti-CD3 in PHA-stimulated cultures, it was not the only apparent inhibitory effect because the addition of exogenous IL 2 could not prevent inhibition completely. Intact AC but not IL 1 also reduced anti-CD3-mediated inhibition of PHA responsiveness, whereas the addition of both IL 2 and AC largely prevented inhibition. Thus, anti-CD3 in the absence of adequate AC signals exerted a number of distinct inhibitory effects on mitogen-induced T cell activation. These results suggest that the CD3 molecular complex may play a role in regulating T cell responsiveness after engagement of the T cell receptor by a number of mechanisms, some of which involve inhibition of IL 2 production.