bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular and genetic restrictions in the immunoregulatory activity of alpha-fetoprotein. III. Role of the MLC-stimulating cell population in alpha-fetoprotein-induced suppression of T cell-mediated cytotoxicity.
Authors: Peck A B , Murgita R A , Wigzell H
Published: December 2022

Alpha-fetoprotein (AFP), a normal component of fetal and newborn sera, exerts selective suppressive effects on various functions of thymus-derived (T) lymphocytes, including the T cell-mediated cytotoxic reaction. In the present study, AFP-induced suppression of the T cell-mediated allogeneic response was examined to define more precisely the mechanism by which AFP acts. Data presented indicate that AFP elicits its effect within the first 25 to 36 hr of culture. However, AFP apparently has no direct effect on T lymphocytes. T cells incubated in the presence of AFP retain full capacity to respond in MLC and CML. In contrast, AFP induces major changes in the functional status of monocyte-enriched, MLC-stimulating cell population. This monocyte-enriched population, after pretreatment with AFP, possesses strong stimulating capacity for the T suppressor cell limb of the immune response, while at the same time, suppresses the activity leading to the normal generation of cytotoxic T lymphocytes. These data correlate with the immune activity present in the newborn mouse.
Unfolded transferrin polypeptide chain is immunologically crossreactive with similar derivatives of serum albumin and alpha-fetoprotein.
Authors: Pekkala-Flagan A , Ruoslahti E
Published: December 2022

Radioimmunoassays utilizing reduced and carboxymethylated (RC) proteins as antigens reveal a cross-reactivity between alpha-fetoprotein (AFP) and albumin. Similar assays were used to study the relationships of AFP and albumin to other serum proteins. Of the several serum proteins tested, transferrin showed the most similarity with AFP and albumin. There was no cross-reactivity of the native proteins, but antisera prepared against RC-albumin and RC-AFP bound 125I-labeled RC-transferrin at high titers, and antiserum to RC-transferrin bound labeled RC-AFP but not RC-albumin. Inhibition assays utilizing binding of 125I-RC-AFP or 125I-RC-transferrin to anti-RC-albumin showed that the RC derivatives of AFP, albumin, and transferrin were equally efficient inhibitors, whereas other serum proteins inhibited much less. The serum vitamin D carrier protein (Gc protein) showed intermediate reactivity. The reactivities of the antisera to RC-albumins with RC-transferrin and RC-Gc protein were corroborated by immunostaining of proteins separated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and transferred to nitrocellulose filters. These antisera stained the bands formed by RC derivatives of albumin, AFP, transferrin, and Gc protein, but not other proteins tested. AFP and albumin are known to have amino acid sequence homology. Our results suggest that transferrin and possibly also Gc protein may be structurally related to AFP and albumin.
Antigen-specific suppression of cytotoxic T cell responses: an idiotype-bearing factor regulates the cytotoxic T cell response to azobenzenearsonate-coupled cells.
Authors: Greene M I , Ratnofsky S , Takaoki M , Sy M S , Burakoff S , Finberg R W
Published: December 2022

When A/J mice are injected subcutaneously with azobenzenearsonate- (ABA) coupled spleen cells, their splenocytes contain primed ABA-specific cytotoxic T lymphocyte (CTL) precursors. Animals that are not primed in vivo do not develop vigorous CTL activity when assessed after in vitro culture with ABA-coupled stimulators. Suppressor molecules derived from ligand-induced first-order ABA-specific suppressor T cells were evaluated for their ability to limit cytolytic T cell development. We have shown that an idiotype-bearing, hapten-specific suppressor factor suppresses priming for CTL in an H-2-unrestricted but allotype-restricted manner. The implication of these studies to regulatory networks is discussed.
Cyclic nucleotides regulate the morphologic alterations required for chemotaxis in monocytes.
Authors: Stephens C G , Snyderman R
Published: December 2022

The initial morphologic response of human monocytes to chemoattractants is a change in shape from round to a triangular "motile" configuration (polarization). At doses chemotactic in vitro, chemoattractants induced rapid (t 1/2 = 45 sec), sustained (greater than 40 min) polarization of monocytes in suspension. Extracellular Ca++ was not required for polarization induced by chemoattractants, but in the absence of Ca++ kinetics were slowed (t 1/2 = 6.5 min). Phenylephrine, carbamycholine, serotonin, and ascorbate also caused rapid polarization of monocytes. Unlike chemoattractants, polarization by the pharmacologic agents was unsustained (less than 15 min), absolutely required extracellular Ca++, and affected about 50% of the cells responsive to chemoattractants. Based on relative sensitivities to alpha 1- and alpha 2-adrenergic agonists and antagonists, polarization caused by adrenergic agents was mediated by alpha 2-receptors. Muscarinic and alpha 2-adrenergic agonists, serotonin, and ascorbate enhanced the rate and number of monocytes polarizing to suboptimal doses of chemoattractants. Thus, the initial morphologic changes induced by chemoattractants appear to utilize an activation pathway shared with a variety of agents that enhance cGMP levels and inhibit adenylate cyclase. In contrast, theophylline, histamine, and isoproterenol, all agents that activate adenylate cyclase and elevate cAMP levels, inhibited monocyte polarization to chemoattractants. As in PMN, pharmacologic agents that increase cAMP levels inhibited monocyte chemotaxis in vitro, whereas those that inhibit adenylate cyclase and increase cGMP enhanced monocyte chemotactic responses. Thus, the initial morphologic response of monocytes to chemoattractants as well as the processes required for sustained directional motility are modulated by cyclic nucleotides.
Heterogeneity of allogeneic restriction of human cytotoxic T cell clones specific for Epstein Barr virus.
Authors: Tanaka Y , Sugamura K , Hinuma Y
Published: December 2022

Clones of human cytotoxic T cells (Tc) specific for Epstein Barr virus (EBV) were isolated from peripheral blood lymphocyte (PBL) cultures stimulated repeatedly with autologous EBV-transformed lymphoblastoid cell line (LCL) cells in vitro. The method employed to clone EBV-specific Tc was a limiting dilution technique utilizing T cell growth factor (TCGF). The EBV specificity of Tc clones was determined by showing that they were significantly cytotoxic for autologous LCL cells but not for either autologous PBL or (natural killer-sensitive) K-562 cells. Eight EBV-specific Tc clones derived from a single donor exhibited distinct cytotoxic patterns against allogeneic LCL targets. Two clones were cytotoxic to LCL targets sharing both HLA-A26 and B15 antigens with effectors, and killing by two other clones was strongly restricted to autologous LCL cells. The four remaining clones showed cytotoxicities against various allogeneic LCL targets irrespective of HLA antigen expression. Eight EBV-specific Tc clones derived from a second donor also exhibited a wide spectrum of cytotoxicity to allogeneic LcL targets. We conclude that EBV-specific Tc, induced in vitro, consist of a number of clones with respect to restrictions imposed by the major histocompatibility complex. The determinants regulating these restrictions may include not only private HLA antigenic determinants that are defined by the HLA serotyping, but also undefined HLA antigenic determinants.
Inhibition of human antibody-dependent cellular cytotoxicity, cell-mediated cytotoxicity, and natural killing by a xenogeneic antiserum prepared against "activated" alloimmune human lymphocytes.
Authors: Neville M E , Hiserodt J C
Published: December 2022

Xenogeneic antiserum (RH1) was prepared in Lewis rats by hyperimmunization with concanavalin A- (Con A) activated alloimmune human lymphocytes. The antiserum RH1 effectively inhibited human antibody-dependent cellular cytotoxicity (ADCC), cell-mediated cytotoxicity (CMC), and natural killing (NK) in the absence of complement (C). Inhibition by RH1 was dependent on the dilution of antiserum employed and the number of cytotoxic lymphocytes present during cytolysis. Pretreatment of lymphocytes with RH1 or the presence of RH1 in culture did not inhibit lymphocyte proliferation stimulated by Con A, phytohemagglutinin, or allogeneic cells; lymphokine production as measured by leukocyte-inhibiting factor production; antibody-dependent C lysis; or CMC mediated by murine cytotoxic T lymphocytes. Analysis of the mechanism of inhibition of cytotoxicity by RH1 revealed that 1) RH1 was not cytotoxic for human lymphocytes at 37 degrees C in the absence of C; 2) purified F(ab')2 fragments were equally inhibitory as whole serum; 3) pretreatment of lymphocytes with RH1 effectively inhibited their capacity to mediate ADCC, CMC, or NK, and this effect was reversible by culturing the cells overnight at 37 degrees C; 4) RH1 did not inhibit target cell binding by K cells, effector cells of ADCC, or alloimmune T cells, but did inhibit binding by NK cells; and finally, 5) the addition of RH1 to preformed lymphocyte-target conjugates in a single cell cytotoxicity assay inhibited killing of the bound target cells in all three systems without disrupting the conjugates. Collectively, these findings suggest that RH1 antiserum interacts with structures present on the surfaces of cytotoxic lymphocytes that are involved in the activation of the lytic mechanism(s) or with the actual lytic molecule or molecules themselves. Furthermore, the ability of RH1 to inhibit ADCC, CMC, and NK during the post-binding cytolytic phase of these reactions indicates that binding and cytolysis are distinct and separate events in all types of cell-mediated cytolysis.
Interactions between lymphocyte membrane molecules. II. Characterization of an interaction between B lymphocyte surface IgD and Fc IgG receptors that differs from the surface IgM-Fc IgG receptor interaction.
Authors: Dickler H B , Kubicek M T , Finkelman F D
Published: December 2022

The B lymphocyte surface membrane receptors IgD (sigD) and Fc IgG receptors (Fc gamma R) were evaluated for interactions by means of immunofluorescence. Ligand-(F(ab')2 anti-delta) induced capping of sIgD resulted in co-capping of Fc gamma R if the latter were occupied during the capping process by soluble antigen-antibody complexes (which themselves provided insufficient cross-linking to result in capping), but not if the Fc gamma R were occupied by monomeric IgG or unoccupied. Capping of Fc gamma R by highly cross-linked complexes did not cause co-capping of sIgD occupied by monomeric F(ab') anti-delta. The interaction between sIgD and Fc gamma R was specific in that cross-reactions between ligands were excluded and ligand-induced capping of sIgD did not cause co-capping of ligand-occupied sIgM or I-A antigens. The sIgD-Fc gamma R interaction occurred on only approximately 60% of B lymphocytes, and this B cell subpopulation did not correlate with other B cell subpopulations (CBA/N strain B cells and B cells bearing either large or small amounts of sIgD). The sIgD-Fc gamma R interaction differed from the sIgM-Fc gamma R interaction in that co-redistribution of the Fc gamma R was occupied by monomeric IgG and involved nearly all B lymphocytes. The qualitative and quantitative differences between the sIgD-Fc gamma R and sIgM-Fc gamma R interactions suggest a mechanism whereby the two antigen receptors could provide different signals to the B lymphocyte.
Antibody restores human alternative complement pathway activation by mouse erythrocytes rendered functionally deficient by pretreatment with pronase.
Authors: Moore F D , Austen K F , Fearon D T
Published: December 2022

Activation of the human alternative pathway of complement (C) by surfaces requires the initial deposition of C3b by fluid-phase C3 convertase and sustained C3 cleavage by C3 convertases fixed to the surface. Nonactivating particles have previously been characterized by an inability to sustain the function of C3 convertases on their surfaces because these sites were susceptible to the regulatory action of the control proteins. Pronase converts the mouse erythrocyte (E) from an activator to a nonactivator by markedly decreasing the ability of the cell to affix C3b generated by a fluid-phase C3 convertase; this conversion is unrelated to the action of the control proteins on bound C3b. The capacity of antibody and its F(ab')2 or Fab' fragments to restore the alternative pathway-activating function of pronase-treated mouse E indicates that the contribution of antibody is mediated by its combining site without a requirement for bridging or for the Fc portion. The fab'-dependent activation of the alternative pathway of C relates to the deposition of C3b on the particle surface, which is a first and continuing step in alternative pathway activation. The antibody effect is not directed to the action of the regulatory proteins. Thus, particle-dependent activation of the alternative C pathway has been shown for the first time to be abolished and restored by cell surface-directed mechanisms that function independently of the regulatory proteins.
Multiple loci mediate B cell repertoire ontogeny: analysis of the hemagglutinin-specific repertoires in neonatal C.B20 and (C.B20 x B10.D2)F1 mice.
Authors: Cancro M P
Published: December 2022

The HA-specific B cell repertoires of 12 to 14-day-old C.B20 and (C.B20 X B10.D2)F1 mice have been characterized and compared to those of BALB/c, B10.D2, and (BALB/c X B10.D2)F1 mice to assess the role of allotype-linked loci in the process of repertoire formation. Both C.B20 and (C.B20 X B10.D2)F1 neonates express repertoires similar to (BALB/c X B10.D2)F1s of the same age, and allotypic analysis indicates that nonparental clonotypes observed in (BALB/c X B10.D2)F1s at this developmental stage are derived predominantly from the B10.D2 parent. In conjunction, these findings indicate that: a) allotype-linked loci, although influential in repertoire formation, clearly interact with loci elsewhere in the genome to shape the expressed repertoire phenotype; b) developmental preference may exist among heterozygous individuals regarding the time at which particular elements of each parental VH haplotype are expressed; and c) the factors that control this preference are dictated by heritable elements unlinked to Ig allotype loci.
Determinants of the localization, magnitude, and duration of a specific mucosal IgA plasma cell response in enterically immunized rats.
Authors: Pierce N F , Cray W C
Published: December 2022

The origin and fate of specific IgA plasma cells in intestinal lamina propria were studied in rats immunized enterically with cholera toxin (CT). Our major goal was to define how an anti-CT response is focused and sustained at the site of antigen challenge. To distinguish antigen-dependent from antigen-independent mechanisms, CT exposure was restricted to defined portions of intestine and, in some studies, the distribution of antitoxin-containing plasma cells (ACC) was examined in nonimmune adoptive recipients of post-challenge thoracic duct lymphocytes. After enteric priming and challenge, ACC appeared throughout the gut, but were most numerous at the challenged site. About 25% of ACC appearing at the site of jejunal challenge were due to antigen-driven proliferation of memory cells within the lamina propria; the remainder arose elsewhere, apparently in mucosal follicles or mesenteric lymph nodes, and migrated systemically as antitoxin-containing plasmablasts before homing to the lamina propria. The homing of these migrating ACC precursors was not affected by mucosal exposure to CT, nor did they undergo appreciable antigen-driven division after arrival in gut lamina propria. However, homing was specific for the organ from which they arose, i.e., precursors arising from duodenal challenge homed selectively to jejunum, whereas those from colonic challenge homed to the colon. The organ specificity of homing was determined during the challenge response and was independent of the origin of memory cells participating in the response. The survival of migrating ACC precursors did not differ in segments of gut exposed or nonexposed to CT. However, CT exposure at the time of their migration evoked another secondary-type response, due to stimulation of comigrating memory cells, thus sustaining the secondary response at a high level. These results and those in a previous report identify important mechanisms that affect the localization, magnitude, and duration of a specific IgA response, at least in the intestine. These include: 1) organ-specific homing of migrating IgA plasmablasts, 2) antigen-driven generation of IgA plasma cells from memory cells within the lamina propria, 3) enhanced memory at the site of mucosal priming compared to that a distant mucosae, and 4) regeneration of memory cells during the secondary response.
Phorbol ester-induced differentiation of a non-T, non-B leukemic cell line: model for human lymphoid progenitor cell development.
Authors: LeBien T W , Bollum F J , Yasmineh W G , Kersey J H
Published: December 2022

The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was tested for its ability to induce phenotypic changes in the human non-T,. non-B ALL cell line REH. Cells were cultured with nanogram concentrations of TPA for up to 48 hr, and were analyzed by indirect immunofluorescence with a panel of monoclonal antibodies and an antibody to the enzyme terminal deoxynucleotidyl transferase (TdT). TPA induced REH cells to express the leukemia-associated antigen, p24 (detected with monoclonal antibody BA-2; p24/BA-2) by 8 hr of culture, with induction complete by 24 hr. TPA-treated cells also underwent a concomitant decrease in the expression of TdT when analyzed enzymatically or by immunofluorescence. Analysis of TPA-treated cells with monoclonal antibodies BA-1 (detecting a B cell-associated antigen), 7.2 (detecting a monomorphic HLA-DR antigen), or OKT11 (detecting a structure closely associated with the E receptor) showed no change compared to controls. In addition there was no detectable cytoplasmic immunoglobulin in control or TPA-treated cells. These results show clearly that TPA is capable of inducing phenotypic changes in REH cells. Such changes may reflect the differentiation-linked expression of antigens present in normal bone marrow lymphoid progenitor cells.
Antibody-induced release of cellular proteinases: loss of adhesion of human melanoma cells after binding of anti-melanoma antibody.
Authors: Singer K H , Hashimoto K , Stuhlmiller G M , Lazarus G S
Published: December 2022

Incubation of monolayer cultures of human melanoma cells with monkey anti-human melanoma IgG resulted in loss of cellular adhesion. Release of melanoma cells from the culture dish was not the result of cytotoxicity. Antibody-induced cell detachment was partially inhibited by the addition of diisopropylfluorophosphate (DFP), and detachment was completely inhibited by the addition of lima bean trypsin inhibitor. Thiol and carboxyl proteinase inhibitors did not block antibody-induced cellular detachment. An IgG dose-dependent increase in DFP-inhibitable caseinolytic activity was demonstrated in the culture medium of melanoma cells incubated with anti-melanoma IgG, but not in those incubated with normal monkey IgG. Medium collected from antibody-treated cell cultures and incubated with protein A-Sepharose to remove IgG caused detachment of melanoma cells in fresh cultures. Preincubation of this conditioned medium from antibody-treated cell cultures with DFP abolished the medium's ability to mediate loss of cellular adhesion. These data suggest that incubation of melanoma cells with immune IgG results in release of a serine proteinase that mediates cellular detachment.
Dna isolated from DNA/anti-DNA antibody immune complexes in systemic lupus erythematosus is rich in guanine-cytosine content.
Authors: Sano H , Morimoto C
Published: December 2022

DNA fragments were isolated from DNA/anti-DNA antibody immune complexes of systemic lupus erythematosus. Hybridization experiments indicated that DNA isolated from immune complexes originates from human nuclear DNA. Two classes of DNA were identified by polyacrylamide gel electrophoresis. The m.w. of small fragments was 25,000 with 30 to 40 base pairs, and that of large fragments was 100,000 with 150 base pairs. The average guanine-cytosine (G-C) content in the small fragments was 55% of total bases, and that in the large fragments was 45%. Compared with the average 38% G-C content of total human DNA, the antigen DNA is rich in G-C content. Such unusually high G-C content can alter DNA structure, which may serve as the target for antibody production.
The immune response to an isomaltohexosyl-protein conjugate, a thymus-dependent analogue of alpha(1 replaced by 6) dextran.
Authors: Stein K E , Zopf D A , Johnson B M , Miller C B , Paul W E
Published: December 2022

Two oligosaccharides derived from B512 dextran (Dex), isomaltohexaose (IM6), and isomaltotriose (IM3) have been coupled to keyhole limpet hemocyanin (KLH) and the conjugates studied as thymus-dependent (TD) immunogens analogous in their specificity to Dex. Both IM3-KLH and IM6-KLH stimulate an anti-Dex response in CBA mice. In C57BL mice, only IM6-KLH stimulated an anti-Dex response; IM3-KLH, although immunogenic, failed to elicit the production of anti-Dex antibodies. Similarly, CBA anti-Dex antibodies cross-reacted with both IM3 and IM6 coupled to bovine serum albumin (BSA), whereas C57BL anti-Dex antibodies cross-reacted with IM6-BSA and bound IM3-BSA only very poorly. This reciprocal lack of cross-reactivity between IM3 conjugates and Dex in C57BL mice was controlled by genes linked to the IgH locus, as shown in responses of allotype congenic CBA mice. This genetically regulated fine specificity pattern was overridden when IM6-KLH was used for immunization. C57BL antibodies that bound both Dex and IM3-BSA were produced in response to this antigen. Thus, isomaltohexosyl-protein conjugates provide Dex-like antigens that differ from Dex itself in terms of thymus dependency and the fine specificity of the precursors that are activated. They should provide important tools to study the activation requirements of antigen-specific B cells.
MLC-specific suppressor T lymphocytes in man. I. Their induction in vitro by soluble HLA-DR antigens.
Authors: Smeraldi R S , Fabio G , Bonara P , Villa M G , Vanoli M , Pettenati C , Rugarli C , Zanussi C
Published: December 2022

Human T lymphocytes precultured for 36 hr in the presence of soluble HLA-DR antigens suppress the MLR response of autologous peripheral blood lymphocytes to allogeneic stimulating cells. The suppression is DR antigen-specific in that it appears that the MLR stimulating cell donor and the soluble suppressor-inducing antigen must share DR specificities. The soluble DR antigens were fractionated from the sera of normal donors using QAE-Sephadex chromatography and CNBr-activated Sepharose immunoadsorption. Similarly prepared HLA-A and -B antigens failed to induce suppressive activity. The suppressive activity of DR-antigen cultured T cells is resistant to mitomycin C treatment and, further, the antigen specificity is maintained with or without mitomycin C treatment. The kinetics of suppressor cell induction as well as the kinetics of suppression in the test MLR cultures are presented. The implications of these results are discussed.
A single monoclonal anti-Ia antibody inhibits antigen-specific T cell proliferation controlled by distinct Ir genes mapping in different H-2 I subregions.
Authors: Germain R N , Bhattacharya A , Dorf M E , Springer T A
Published: December 2022

A xenogeneic rat anti-mouse Ia monoclonal antibody, M5/114 (gamma 2b, kappa), was studied for its effects in vitro on T cell proliferative responses. Strain distribution studies revealed that M5/114 could inhibit I-A subregion-restricted T cell responses of the H-2b,d,q,u but not the H-2f,k,s haplotypes, indicating that this xenoantibody recognizes a polymorphic determinant on mouse Ia molecules. This same monoclonal antibody was found to inhibit BALB/c (H-2d) T cell proliferation to both G60A30T10 and G58L38 phi 4. The Ir genes regulating responses to these antigens map to either the I-A subregion (GAT), or the I-A and I-E subregions (GL phi), raising the possibility that M5/114 recognizes both I-A and I-E subregion-encoded Ia glycoproteins. It could be shown, using appropriate F1 responding cells, that M5/114 does in fact affect GAT and GL phi responses by interaction with both the I-A and the I-E subregion products, and not by any nonspecific effect resulting from binding to the I-A subregion product alone. These results are consistent with genetic and biochemical studies directly demonstrating that M5/114 recognizes A alpha A beta and E alpha E beta molecular complexes. The existence of a shared epitope on I-A and I-E subregion products suggests the possibility that these molecules arose by gene duplication. Finally, the precise correlation between the Ia molecules recognized by M5/114 and the ability of this antibody to block T cell responses under Ir gene control strengthens the hypothesis that Ia antigens are Ir gene products.
Antigen-specific human T lymphocyte clones: viral antigen specificity of influenza virus-immune clones.
Authors: Lamb J R , Eckels D D , Phelan M , Lake P , Woody J N
Published: December 2022

Human T lymphocyte clones (TLC) specific for type A (A/Texas/1/77) influenza virus and maintained in continuous culture with T cell growth factor, were analyzed to define the cellular specificity pattern of virus recognition. A panel of TLC were stimulated with strains of serologically characterized type A influenza subtypes. Five TLC recognized all the viral subtypes; the remaining clones recognized only subtypes that shared serologically defined determinants with the immunizing subtype. In addition, the 11 TLC were analyzed for their fine antigenic specificity by using the purified viral components hemagglutinin (HA), neuraminidase (NA), matrix protein (MP), and nucleoprotein (NP). Five TLC proliferated in response to NA, four to MP, one to HA, and one to NP. None of the clones responded to the unrelated B strain influenza virus, B/Singapore. Furthermore, the fine specificity of an MP-reactive TLC was confirmed by subcloning.
The fourth component of human complement treated with amines or chaotropes or frozen-thawed (C4b-like C4): interaction with C4 binding protein and cleavage by C3b/C4b inactivator.
Authors: von Zabern I , Bloom E L , Chu V , Gigli I
Published: December 2022

We have shown previously that C4 treated with amines or chaotropes, although uncleaved, exhibits properties that are similar to C4b. Studies by other groups suggest that this C4b-like form of C4 is characterized by the lack of an internal thiolester bond that is present in native C4. We report here that C4 treated with N2H4 or KSCN or frozen-thawed, unlike native C4, forms a complex with C4-binding protein (C4-bp) and is cleaved by C3b/C4b inactivator (I). Fragmentation of C4b-like C4 by I occurs without previous cleavage to C4b and requires the presence of C4-bp. Cleavage of C4b-like C4 proceeds in two steps: a small fragment (16,000 m.w.) is released first, followed by cleavage of the remaining alpha-chain fragment (83,000 m.w.) into polypeptides of 46,000 (C4d) and 32,000 m.w. All fragments, except the 46,000 m.w. fragment, are disulfide-linked to the beta- and/or gamma-chains of C4. Cleavage of C4b-like C4 probably occurs at the same points in the alp a-chain as in C4b; however, C4b-like c4 also contains C4a. Based on the m.w. determinations, the C4a portion of the alpha-chain is present in the 83,000 m.w. fragment, and after the second cleavage, in the 32,000 m.w. fragment of C4b-like C4. These findings suggest the following alignment of alpha-chain fragments: the N-terminal C4a portion is attached to a polypeptide of about 25,000 m.w. (alpha 3), which is followed in the sequence by C4d (alpha 2) (46,000 m.w.) and a small 16,000 m.w. fragment (alpha 4) that forms the C-terminus.
Inhibition of secondary in vitro antibody responses by the third component of complement.
Authors: Hobbs M V , Feldbush T L , Needleman B W , Weiler J M
Published: December 2022

Purified human C3 was found to inhibit rat in vitro secondary antibody responses. Fifty percent inhibition of antibody-forming cell development occurred with C3 concentrations of 26 micrograms/ml. This decrease was not the result of a general toxicity or a shift in the antibody response kinetics. Using cell mixing experiments, we could not detect a C3-induced suppressor lymphocyte or macrophage. C3 was active when added to culture early (day 0 or 1 or during a 24-hr antigen prepulse) or late (day 3, 5, or 7)--the early addition being more suppressive. Regardless of the addition time, there was a characteristic 48- to 72-hr lag before the inhibitory effect was manifested. C3 could inhibit antibody-forming cell development after stimulation with the thymus-independent antigens, trinitrophenyl-Brucella abortus and dinitrophenyl-Ficoll, as well as the thymus-dependent antigens, dinitrophenyl-bovine gamma-globulin and chicken gamma-globulin suggesting that C3 was not selective for B memory cell subpopulations. Further characterization of our C3 preparation indicated that the majority of the suppressive activity resided in a small m.w. protein resembling the C3a fragment of C3. Human C3a preparations generated either by trypsin cleavage or zymosan activation of C3 were also tested in our antibody response system and were able to inhibit antibody-forming cell development. These data implicate C3 cleavage products as negative regulators of antibody formation.
Studies on the ability of monoclonal antibodies to selectively mediate complement-dependent cytotoxicity of human myelogenous leukemia blast cells.
Authors: Ball E D , Kadushin J M , Schacter B , Fanger M W
Published: December 2022

A panel of monoclonal antibodies that bind to leukemic blast cells from patients with acute myelocytic leukemia and chronic myelocytic leukemia in blast crisis was studied for their ability to mediate complement-dependent lysis of a variety of cell populations from patients with leukemia, normal blood cells, and human leukemia cell lines. Several of these monoclonal antibodies were selectively cytotoxic to myeloid leukemia cells (AML-1-99, AML-1-211, AML-2-30, CML-75, CML-115, and CML-150). Although they were all capable of binding to normal cell populations, none of these hybridomas were cytotoxic to normal cells. Three of these antibodies (AML-1-211. CML-75, and CML-150) were cytotoxic to some leukemia cell samples only after dilution of the hybridoma supernatant, i.e., they showed a prozone. Binding of these three antibodies, as well as another, AML-1-201, as determined in a radioimmunoassay, also showed a prozone. Other monoclonal antibodies are described (AML-2-23 and AML-2-9) that mediate complement-dependent cytotoxicity to myeloid leukemia cells as well as selected normal cell types (monocytes and lymphocytes, respectively). The potential clinical utility of these monoclonal antibodies is considered in the context of recently encountered problems in the use of monoclonal antibodies to mediate leukemia cell lysis in vivo.
Antigen presentation to T cell hybridomas by a macrophage cell line: an inducible function.
Authors: Birmingham J R , Chesnut R W , Kappler J W , Marrack P , Kubo R , Grey H M
Published: December 2022

We have investigated the ability of an Ia-, nonantigen-presenting macrophage tumor cell line, P388D, (H-2d), to present antigen to T cell hybridomas after incubation in a lymphokine-containing preparation. P388D, cells were incubated in microtiter wells with various concentrations of Con A-stimulated spleen cell supernatants. Antigen-specific stimulation of H-2d-restricted, KLH-specific T cell hybridomas was observed by P388D1 incubated with SUP.P388D1 cells incubated for 3 days in medium or control SUP did not present antigen. In addition, no stimulation of T hybridomas was seen by P388D1 in the inhibited by the appropriate monoclonal anti-Ia reagents. These results demonstrate that a macrophage tumor cell line can be induced to present antigen and provides for large numbers of readily available, homogeneous macrophages for studying the cellular biochemical requirements for antigen processing and presentation.
Complexity of the human T lymphocyte-specific cell surface antigen T3.
Authors: Borst J , Prendiville M A , Terhorst C
Published: December 2022

A human T lymphocyte cell surface antigen T3 was found to be involved in several functions that were specific for the cells that express this marker on their surface. We show here that several glycoproteins were found in the immunoprecipitates prepared with a monoclonal reagent anti-T3. In addition to the major glycoprotein complex of 20 kd, glycoproteins of 25 to 28 kd, 37 kd, and 44 kd were detected in immunoprecipitates. The charge heterogeneity of the 20 kd and 25 to 28 kd proteins was caused by variable sialic acid content. The 20-kd T3 glycoprotein carried several "complex-type" and endoglycosidase-H-sensitive sugar moieties. We found that the 20-kd protein could be labeled with 125I-iodonaphthylazide, a reagent that reacts with hydrophobic areas of proteins.
Hemolytic efficiency of cell-bound IgM: evidence that IgM-C1 complexes activate C4 molecules not hemolytic with homologous C2--C9.
Authors: Ejzemberg R , Borsos T
Published: December 2022

The hemolytic efficiency of rabbit-anti-Forssman IgM antibody depends on the source of complement components. With whole guinea pig complement as few as one in 10 IgM molecules was hemolytic; it was found that with purified guinea pig C1, C4, and C2 components and with rat late-acting components, all IgM molecules were hemolytic. Evidence indicates that the block occurred as a result of generating at least two different cell-bound C4 molecules, one of which was not competent with homologous late-acting components.
Control of IgM synthesis in the murine pre-B cell line, 70Z/3'.
Authors: Mains P E , Sibley C H
Published: December 2022

The murine 70Z/3 tumor resembles a pre-B cell in synthesizing only intracellular mu-chains and no detectable light chain. However, one kappa gene is already rearranged, and after overnight incubation with lipopolysaccharide (LPS), most of the cells are induced to synthesize light chain. The induced cells display IgM on their surface, but do not secrete IgM. Thus, 70Z/3 cells resemble cells poised at the pre-B cell/B lymphocyte border. We have examined synthesis and post-translational modification of mu-chains in uninduced and induced 70Z/3 cells. Isolation of mu-chains and peptide maps demonstrated that both populations synthesize intracellular forms that correspond to membrane-specific mum and secretion-specific mus chains. These intracellular forms have completed only the first of the two glycosylation steps characteristic of eukaryotic cells. After induction by LPS, L chain synthesis commences, mum and mus synthesis are both increased twofold to threefold (due to an increased rate of synthesis rather than decreased degradation), and both complex with L chain to form mu2L2 tetramers. Furthermore, the glycosylation of a subset of the mum chains is completed, and these are placed on the membrane. However, unglycosylated mu2L2 tetramers can be placed on the membrane, so glycosylation is not a requirement. These data suggest that L chain may not be sufficient for externalization of mum and mus chains. These data support the idea that the controls of membrane placement and secretion of mu chains are post-translational and that different mechanisms operate for mum and mus chains.
The requirement of specific anticapsular IgG for killing of Haemophilus influenzae by the alternative pathway of complement activation.
Authors: Tarr P I , Hosea S W , Brown E J , Schneerson R , Sutton A , Frank M M
Published: December 2022

Employing an in vitro bactericidal assay using C4-deficient guinea pig serum (C4D-GPS), we evaluated the ability of the alternative pathway to kill a number of strains of encapsulated and unencapsulated Haemophilus influenzae (HI). Complement activation occurred, but no bactericidal activity was observed against any of the tested HI in nonimmune C4D-GPS without detectable antibody to HI-type b (HIb) capsular polysaccharide (HIb-ps). In the presence of high-titered human anti- (type b) IgG, C4D-GPS killed the encapsulated strains. Restoration of classical pathway activity by the addition of purified C4 to C4D-GPS, which contained antibody to somatic antigens, resulted in killing of some strains of both encapsulated and unencapsulated HI. In nonimmune C4D-GPS the alternative pathway is activated but does not mediate bactericidal activity. The addition of specific high-titered anticapsular IgG results in killing of encapsulated HI by the alternative pathway in guinea pig serum.
Abnormal in vitro proliferation of splenic mononuclear phagocytes from autoimmune motheaten mice.
Authors: McCoy K L , Chi E , Engel D , Rosse C , Clagett J
Published: December 2022

Motheaten mice develop combined immunodeficiency and fatal autoimmune disease that follow autosomal recessive inheritance. In splenocyte cultures of motheaten mice, supplemented with 5% normal serum proliferating cells (MP) were present exhibiting morphologic characteristics of mononuclear phagocytes at light and electron microscopic levels. The macrophage nature of these cells was confirmed by the lack of Thy-1 antigen and immunoglobulins; the expression of Mac-1 antigen, FcR for IgG, and Ia antigens on their cell surfaces; their ability to phagocytize EA and adhere to plastic; the presence of nonspecific esterase and lysomal enzymes in their cytoplasm; and the pattern of peroxidase localization similar to monocyte-derived macrophages. MP from motheaten mice exponentially grew in culture in the absence of exogenous growth factors with a doubling time of approximately 76 hr. Although these cells were present in splenocyte cultures of normal controls, their number did not increase during the culture period under the same conditions. The addition of dextran sulfate further enhanced the proliferation of MP from motheaten mice, and induced exponential growth of these cells from normal controls, reaching only the level of unstimulated cells from motheaten mice. Radioautographic analysis demonstrated that MP substantially contributed to the elevated spontaneous and dextran sulfate-induced DNA synthesis in splenocyte cultures. Therefore, the in vitro abnormality of MP may be indicative of in vivo aberrancies of macrophages from motheaten mice and lends credence for investigating the role of macrophages in immunodeficiency and autoimmunity that develop very early in motheaten mice.
Circulating autoantibodies to IgD in rheumatic diseases.
Authors: Pope R M , Keightley R , McDuffy S
Published: December 2022

Most mature B lymphocytes possess IgD on their cell surface. Antibodies to IgD produce an adjuvant-like effect in many experimental systems. Employing sensitive class-specific radioimmunoassays, elevated concentrations of autoantibodies to IgD of the IgA, IgM, and IgG classes were detected in the sera of 55% of patients with adult onset rheumatoid arthritis (RA), of 45% with systemic lupus erythematosus (SLE), of 67% with mixed connective tissue disease syndrome (MCTD), and of only 8% of juvenile RA. Marked differences in the class of anti-IgD were noted. An elevated IgA anti-IgD was detected in 45% (p less than 0.01) of RA sera, 27% of SLE sera, and 58% (p less than 0.01) of MCTD sera. IgG anti-IgD was increased in only 26% of RA, 32% of SLE, and 8% of MCTD sera. IgM anti-IgD was elevated in only one patient. IgA anti-IgD was inhibited greater than 90% by IgD but not at all by IgG. Correlations between the concentration of immunoglobulin G and IgA anti-IgD were noted in RA (rs = 0.37, p = 0.02), SLE (rs = 0.46, p = 0.015), and MCTD (rs = 0.4). These data suggest a potential role for autoantibodies to cell surface IgD as modulators of the immune system in some patients with autoimmune disorders.
Restricted deposition of C3 on M+ group A streptococci: correlation with resistance to phagocytosis.
Authors: Jacks-Weis J , Kim Y , Cleary P P
Published: December 2022

In this report, the mechanism of resistance to phagocytosis by group A streptococci and the participation of M protein in this process were studied. A quantitative fluorometric immunoassay was used to determine the amount of the opsonic third component of complement, C3, fixed by group A streptococci in the presence and absence of M protein. In the absence of M protein, phagocytosis was found to be dependent on the amount of C3 fixed. However, when M protein was present, the streptococci still bound sufficient C3 to have promoted phagocytosis, yet none was observed. Further investigation using immunofluorescent microscopy demonstrated that the C3 fixed to M+ chains was confined to dense patches, interspaced by areas devoid of detectable C3. This uneven distribution of C3 was dependent on the presence of a trypsin-sensitive structure; most likely the M protein. The significance of this restricted C3 deposition with respect to resistance to phagocytosis by group A streptococci is discussed.
Serologic and cellular characterization of products of a new major histocompatibility gene region, RT1.C, of the rat; possible homology to mouse H-2 Qa.
Authors: Stock W , Günther E
Published: December 2022

The A region of the major histocompatibility system of the rat, RT1, codes for ubiquitously expressed class I antigens and the RT1.B region determines class II (Ia) molecules. A third region, RT1.C, adjacent to B, has been described recently by histogenetic methods. Data are now presented on the analysis of RT1.C region products by the use of alloantisera and cytotoxic T lymphocytes, both prepared in two, C region congenic strain combinations. C region antigens have been detected serologically by complement-dependent cytotoxicity assays on the majority of B and T lymphocytes, but not on erythrocytes or liver and brain tissue by absorption tests. With the typing sera available only three "alleles" could be identified among 13 different rat strains, so that the RT1.C polymorphism appears to be restricted. Cytotoxic T lymphocytes could be induced against C region products after in vivo immunization and in vitro restimulation; killing was not restricted by the A and B regions. The concept that RT1.C is homologous to H-2 Qa is discussed.
Characterization of two subsets of human T gamma cells.
Authors: van de Griend R J , ten Berge I , Tanke H J , Roos D , Schellekens P T , Melief C J , Zeijlemaker W P , Astaldi A
Published: December 2022

Normal human E rosette-forming, Fc-IgG receptor-bearing cells (so-called T gamma cells) were separated into two functionally different subpopulations. Both subpopulations bind the monoclonal antibody OKM1 (directed against an antigen present also on monocytes and granulocytes). The first subpopulation accounts for about 70% of the total T gamma cell population, does not bind OKT3 (a monoclonal antibody directed against an antigen present on most T lymphocytes), and displays strong killer (K) cell and natural killer (NK) cell activity. The second subpopulation accounts for about 30% of the total T gamma population, binds both OKT3 and OKM1 (confirmed with a double-labeling assay), and displays low K and NK cell activity. Each subset contained less than 10% null cells. Comparison of T gamma cell populations obtained by adherence to a monolayer of IgG-coated human erythrocytes or by rosette formation with these cells revealed that pure T gamma cells with normal killer cell and natural killer cell activity were best obtained with the monolayer technique. Comparison of the enzymic and functional profile of T gamma cells, monocytes and granulocytes, as well as changes during culture of these cells in vitro, failed to indicate a relationship between T gamma cells and cells of the myelomonocytic lineage.
Human B cell alloantigens: expression of MB and MT determinants.
Authors: Markert M L , Cresswell P
Published: December 2022

Four HLA-DR-homozygous cell lines were examined in detail to compare alpha and beta subunits precipitated by chimpanzee antisera and alloantisera directed against HLA-DR, MB, or MT determinants. For the HLA-DR5-homozygous cell line Sweig, chimpanzee antisera directed against MT2 and against the HLA-DR5 specificity yielded identical patterns. Similar findings for MT and MB vs HLA-DR were obtained for the cell lines LG14 (HLA-DR3-homozygous), PBur (HLA-DR7-homozygous), and Eld (HLA-DRw6-homozygous). Therefore, on some cell lines MT and/or MB specificities appear to be detectable only on the same or electrophoretically identical alpha-beta complexes as HLA-DR determinants.
Resistance against Trypanosoma cruzi associated to anti-living trypomastigote antibodies.
Authors: Krettli A U , Brener Z
Published: December 2022

A dissociation between antibodies involved in the diagnosis of Trypanosoma cruzi infections and those participating in resistance against this parasite is reported. Mice immunized with different T. cruzi antigens (frozen-thawed culture forms, glutaraldehyde-fixed blood trypomastigotes, "metabolic antigens" from blood parasites, and surface glycoprotein from epimastigotes) present only antibodies detected by conventional immunofluorescence tests (IFA) using fixed parasites. However, mice chronically infected with T. cruzi harbor both reactive IFA antibodies and antibodies against living blood forms (ALBA) detectable by complement-mediated lysis (CML). Challenge of the various groups of animals with virulent T. cruzi show that only mice presenting ALBA are strongly resistant. In addition, the antibody lytic activity is lost in mice parasitologically cured after specific treatment. Those findings strongly suggest that ALBA are good markers for monitoring protection in experiments of vaccination against T. cruzi. They also support our previous suggestion that the search for antibodies against living blood forms, detected mainly by CML, is an important element in establishing a reliable criterion of cure in human Chagas' disease.
B lymphocyte subpopulation defined by a rat monoclonal antibody, 14G8.
Authors: Kung J T , Sharrow S O , Ahmed A , Habbersett R , Scher I , Paul W E
Published: December 2022

14G8 is monoclonal rat antibody that recognizes an antigen found on 30 to 40% of B lymphocytes from normal mice and on approximately 65% of B lymphocytes from mice with the xid-determined immune defect. 14G8+ B cells from normal mice resemble B cells from mice with the xid-determined defect in that the median amount of membrane IgM expressed per cell is much larger than that of 14G8- B cells. The frequency of 14G8+ cells is highest in neonatal mice (approximately 55% of all spleen cells) and falls with age to approximately 25% of all spleen cells in adult mice. Relatively few lymph node or bone marrow B cells express the antigen recognized by 14G8. 14G8 also reacts with 50% of resident peritoneal cells and with red blood cells. 14G8+ and 14G8- B cell preparations were obtained by fluorescence-activated cell sorting and by adherence to 14G8 coated dishes. 14G8+ cells responded with in vitro proliferation to both anti-mu and to LPS. Cell cycle analysis indicated that approximately 33% of these cells entered S phase in response to LPS and 38% in response to anti-mu. In contrast, 14G8- cells responded poorly to LPS (7% of cells entered S phase) although they showed good responses to anti-mu (40% of cells entered S phase). Thus, 14G8+ B cells, despite their similarity to B cells from mice with the xid defect, can proliferate to anti-mu, which B cells from defective mice fail to do. 14G8 provides a monoclonal antibody valuable in the description of functional B cell subpopulations.