bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selected antibodies to leukocyte common antigen (CD45) inhibit human neutrophil chemotaxis.
Authors: Harvath L , Balke J A , Christiansen N P , Russell A A , Skubitz K M 
Published: December 2022

Abstract
The CD45 Ag family is a group of high m.w. glycoproteins that are expressed on the plasma membranes of all leukocytes. CD45 has protein tyrosine phosphatase activity and appears to regulate signal transduction and lymphocyte activation by specific association with receptor molecules on T and B lymphocytes. However, little is known about CD45 function in neutrophils (PMN). In this study, PMN were incubated with CD45 mAb and tested for their chemotactic responses to four unrelated chemo-attractants: FMLP, leukotriene B4 (LTB4), recombinant human C5a (C5a), and recombinant human neutrophil-activating protein-1, recently designated IL-8. A panel of CD45 mAb including an IgM mAb, AHN-12.1, and six IgG1 mAb, AHN-12, AHN-12.2, AHN-12.3, AHN-12.4, HLe-1, and KC56(T200), were tested for their effects on PMN chemotaxis. PMN chemotaxis was evaluated with two different membrane assays; one assay quantified the total number of migrating PMN and the other assayed the leading front of migrating PMN. AHN-12.1 and KC56(T200) significantly inhibited PMN chemotaxis to LTB4 and C5a. AHN-12.1 slightly inhibited PMN chemotaxis to FMLP, but KC56(T200) did not. In contrast, AHN-12 and HLe-1 did not significantly inhibit PMN chemotaxis to any of the chemoattractants. None of the CD45 mAb inhibited PMN chemotaxis to neutrophil-activating protein-1/IL-8. None of the CD45 mAb inhibited PMN superoxide production. These results suggest that PMN CD45 epitopes may interact with LTB4 and C5a receptor-associated molecules and regulate chemotactic responses.
In vivo functional clonal deletion of recipient CD4+ T helper precursor cells that can recognize class II MHC on injected donor lymphoid cells.
Authors: Kiziroglu F , Miller R G 
Published: December 2022

Abstract
Intravenous injection of semiallogeneic (C57BL/6XDBA/2)F1 lymphocytes into adult C57BL/6 recipient mice not only, as previously reported, reduces the recipients' cytotoxic T lymphocyte response in a subsequent in vitro mixed lymphocyte reaction against the injected cell type, but also reduces Th cell function in the same MLR. Thus lymphoid cells derived from the injected mice were greatly reduced in their ability to proliferate and to produce IL-2 in response to (C57BL/6XDBA/2)F1 stimulator cells in vitro, whereas third party responses were unaffected. This appears to be due to a reduction in the precursor frequency of IL-2-producing T lymphocytes specific for the injected cells as measured by limiting dilution analysis. Similar donor-specific reduction in the frequency of precursors of IL-2-producing cells was seen after i.v. injection of A.TL lymphocytes into A.TH recipients (differing at class II determinants I-A and I-E, but identical at K and D). Here there also appeared to be a functional clonal deletion of precursors of IL-2-producing Th cells, shown directly to be class II MHC reactive and CD4+. There is strong evidence that the reduction of class I-specific cytotoxic responses in the injected mice is a manifestation of donor cells that function as veto cells, i.e., that function as deletional APC that inactivate class I-reactive CTL precursors that recognize them. Our data in this study show that class II-specific Th responses are similarly reduced in the injected mice and suggest that CD4+ class II-reactive precursors of Th cells may be functionally inactivated in vivo by donor cells via a veto-like mechanism.
CD4+ suppressor cells inhibit the function of effector cells of experimental autoimmune encephalomyelitis through a mechanism involving transforming growth factor-beta.
Authors: Karpus W J , Swanborg R H 
Published: December 2022

Abstract
Nylon wool adherent, CD4+ T cells from the spleens of rats that have recovered from experimental autoimmune encephalomyelitis (EAE) inhibit the in vitro production of IFN-gamma, but not IL-2, by effector cells of EAE when cocultured in the presence of myelin basic protein Ag. When anti-transforming growth factor-beta (TGF-beta) antibodies are added to the co-cultures, IFN-gamma production is restored to normal levels. Irrelevant control antibodies have no effect. The same pattern of response was obtained with cells incubated in serum-free medium. In other experiments, purified TGF-beta was added to cultures of effector cells in the presence of antigen. TGF-beta inhibited the production of IFN-gamma by these cells in a dose-dependent manner, but had no apparent inhibitory effect on IL-2 production. Finally, supernatants from cultures containing effector cells and CD4+ suppressor cells plus Ag contained measurable amounts of TGF-beta, whereas supernatants from cultures of effector cells plus Ag contained no measurable amounts of TGF-beta. These results suggest that CD4+ Ts cells of EAE regulate effector cells of EAE through a mechanism that involves the secretion of TGF-beta and that the inhibitory function of this cytokine can be reversed with neutralizing antibodies directed against TGF-beta.
Monocyte chemotaxis and activating factor production by keratinocytes in response to IFN-gamma.
Authors: Barker J N , Jones M L , Swenson C L , Sarma V , Mitra R S , Ward P A , Johnson K J , Fantone J C , Dixit V M , Nickoloff B J 
Published: December 2022

Abstract
Monocytes accumulate in the epidermis and along the dermo-epidermal junction in several different inflammatory skin diseases. To determine whether human epidermal keratinocytes elaborate a specific chemotaxin responsible for the accumulation of monocytes at these anatomic sites, monocyte chemotactic activity in conditioned 16-h cultured keratinocyte supernatants were assayed using human peripheral blood monocytes as the target cell. Dilutional analysis revealed directed monocyte migration in IFN-gamma-treated (100 U/ml) keratinocyte supernatants (80% maximal FMLP response) which was 10-fold more than IFN-gamma itself or untreated keratinocyte activity alone. Gel filtration chromatography revealed that this activity eluted just ahead of a 12.5-kDa molecular mass marker. Blocking studies demonstrated that a rabbit polyclonal antibody to monocyte chemotaxis and activating factor (MCAF) inhibited all monocyte chemotaxis by greater than 80%. Keratinocytes were metabolically labeled with 35S-cysteine/methionine, and after 16 h incubation the supernatants immunoprecipitated with the same anti-MCAF antibody. MCAF was detected as a protein doublet of 12 and 9 kDa only in IFN-gamma-treated (100 U/ml) keratinocyte supernatants. Incubation with IFN-gamma and TNF-alpha (250 U/ml) in combination resulted in increased production of MCAF protein. By Northern blot analysis, MCAF mRNA was constitutively expressed in keratinocytes and upregulated only in the presence of IFN-gamma. TNF-alpha, IL-1 beta, transforming growth factor-beta and phorbol esters had no positive or negative influence on MCAF mRNA. These studies demonstrate that biologically active MCAF is elaborated by human epidermal keratinocytes upon activation by IFN-gamma, a cytokine also required for the induction of adherence between monocytes and keratinocytes. Keratinocyte-derived MCAF is likely to be important in the regulation of cutaneous monocyte trafficking and may also be responsible for the recruitment of Langerhans cells and dermal dendrocytes, which share many phenotypic features with monocytes/macrophages, to their anatomic locations in skin.
IFN-gamma reduces specific binding of tumor necrosis factor on murine macrophages.
Authors: Drapier J C , Wietzerbin J 
Published: December 2022

Abstract
Because IFN-gamma is the main cytokine activating macrophages and TNF cooperates in this activation, we assessed TNF binding capacity during the course of murine macrophage activation by IFN-gamma. TNF binding to elicited macrophages increased with time, was maximal by 8 h of culture, and required de novo protein synthesis. 125I-TNF bound to about 40,000 sites/cell with a Kd of 1 x 10(-9) M. Cross-linking experiments performed with a bifunctional cross-linking agent revealed a specific band with a m.w. of 94,000. Preincubation of macrophages with IFN-gamma prevented the binding of TNF to receptors. This effect was dose-dependent and maximal at 100 U/ml. IFN-gamma also reduced specific TNF binding to preexisting receptors (50% inhibition in 3 h), but IFN-gamma did not change the internalization rate of TNF. These studies showed that the number of TNF receptors increased on macrophages vs maturation in culture and was negatively controlled by IFN-gamma.
Dexamethasone inhibits the induction of monocyte chemotactic-activating factor production by IL-1 or tumor necrosis factor.
Authors: Mukaida N , Zachariae C C , Gusella G L , Matsushima K 
Published: December 2022

Abstract
Recently purified and molecularly cloned monocyte chemotactic and activating factor (MCAF) may play a major role in recruiting and activating monocytes in the inflammatory process. We examined the effects of a potent anti-inflammatory agent, dexamethasone (DXS), on the production of this factor. Over a wide range of concentrations (10(-5) to 10(-8) M), DXS inhibited the production of MCAF at the mRNA and protein level in a human fibrosarcoma cell line, which was stimulated with either IL-1 or TNF-alpha. We examined the turn-over of synthesized MCAF mRNA that showed DXS decreased the stability of MCAF mRNA. Furthermore, the addition of actinomycin D and cycloheximide abolished this effect of DXS, indicating that de novo mRNA and protein synthesis were required for this process. In addition, a nuclear run-off analysis revealed that DXS also inhibited the transcription of IL-1- or TNF-activated MCAF genes. Therefore, both the destabilization of MCAF mRNA and the inhibition of transcription of the gene contribute to the decrease in the MCAF mRNA steady state level by DXS.
Exogenous C1q reconstitutes a secondary deficiency of C5-deficient AKR mouse macrophages for FcR-dependent cellular cytotoxicity and phagocytosis.
Authors: Leu R W , Zhou A Q , Kennedy M J , Shannon B J 
Published: December 2022

Abstract
Studies originally designed to assess the putative role of endogenous C5 in macrophage activation for antibody-dependent cellular cytotoxicity (ADCC) yielded unanticipated results. Resident and inflammatory peritoneal macrophages from C5-deficient AKR mice were found to have significantly lower capacity for FcR-dependent ADCC activation and phagocytosis of IgG-opsonized SRBC targets than did C5-competent C3HeB/FeJ (C3H) mice. Reconstitution of the ADCC response of AKR macrophages was accomplished initially with C5-sufficient C3H mouse serum, which suggested that endogenous C5 may be required for ADCC activation. However, further investigation largely eliminated C5 involvement in that a heat-labile component of C5-deficient AKR serum was shown to be active in the reconstitution of ADCC activation of AKR macrophages. Macrophages from AKR mice were found to have significantly lower levels of C1q mRNA synthesis, endogenous C1q levels, and C1q secretion than did C3H mouse macrophages as determined by Northern blot, Western blot, and presynthetic radiolabeling analysis, respectively. The addition of purified exogenous C1q to IgG-opsonized SRBC targets fully reconstituted ADCC activation for AKR inflammatory peritoneal macrophages to levels of normally FcR-responsive C3H macrophages. Similarly, exogenous C1q augmented FcR-dependent phagocytosis of AKR macrophages but had no effect on macrophages from responsive C3H mice. Our results indicate that AKR mice have a deficiency for FcR-dependent cellular cytotoxicity and phagocytosis that is related to their low potential for C1q synthesis and secretion rather than to their established genetic deficiency for C5 synthesis. We tentatively conclude that endogenous C1q is required as an accessory molecule for macrophage FcR-dependent effector functions and that C5 is not a prerequisite for ADCC activation.
The antigenic surface of staphylococcal nuclease. I. Mapping epitopes by site-directed mutagenesis.
Authors: Smith A M , Woodward M P , Hershey C W , Hershey E D , Benjamin D C 
Published: December 2022

Abstract
The analysis of the antigenic surface of staphylococcal nuclease was begun by generating and characterizing a panel of mAb. Twelve mAb were selected from a large number of anti-nuclease mAb and characterized for affinity and isotype, by their ability to block enzyme activity, and by complementation and competitive inhibition assays for the relative location of epitopes. The mAb were placed in complementation groups based on their distinct binding patterns. These groups define a series of eight overlapping epitopes that are estimated to cover a large portion of the nuclease surface. Four mAb blocked the enzyme activity of nuclease. The epitopes defined by two of these four mAb were localized on the surface of nuclease using single amino acid variant Ag generated by site-directed mutagenesis of the cloned nuclease coding sequence. mAb-25 maps to residue 46 which is located at the edge of the enzyme active site consistent with its ability to inhibit enzyme activity. mAb-19, which also blocks enzyme activity and belongs to the same complementation group as mAb-25, was unaffected by the substitution at position 46. This suggests that mAb-19 and mAb-25, if they do react with the same epitope, have differences in fine specificity. mAb-22 blocks enzyme activity and belongs to an overlapping complementation group. The fourth mAb, mAb-1, which belongs to a distinct, nonoverlapping, complementation group, does not blocks enzyme activity, and is directed to a region of nuclease that includes the amino acid at position 133. This residue is located a short distance from the active site in a region that has been suggested to participate in binding of DNA, a substrate for nuclease. Therefore, the four epitopes defined by these mAb are localized at or near the enzyme active site.
Down-regulation of surface FcRI and decrease in antibody-dependent cellular cytotoxicity of cultured monocytes. Reversal by monensin or cytochalasin-D.
Authors: Tripathi A K , Taplits M , Puri J , Hoffman T 
Published: December 2022

Abstract
To investigate the mechanisms involved in regulation of antibody-dependent cellular cytotoxicity (ADCC) mediated by human monocytes, 51Cr-labeled sheep red blood cells (RBC) were used as target cells in vitro. Monocytes incubated overnight at 37 degrees C before addition of SRBC and antibody exhibited a significant decrease in ADCC activity compared with freshly isolated cells. This pattern was observed with monocytes from all donors tested, regardless of the media used for culture. Supernatants from monocyte cultures did not inhibit the cytotoxic ability of fresh monocytes and cycloheximide, a protein synthesis inhibitor, could not reverse ADCC suppression in cultured monocytes, indicating that the alteration in ADCC is probably not due to inhibitory molecules secreted or synthesized during incubation. A correlation between the decrease in the number of surface FcRI and loss in ADCC ability of cultured monocytes was found. One mechanism for the reduced FcRI expression of 1-day-old monocytes may be rapid internalization that exceeds the rate of reexpression, because cytochalasin-D or monensin, each of which inhibits receptor internalization, maintained FcR expression as well as ADCC ability of cultured monocytes. These data illustrate mechanisms whereby alteration in the number of receptors may underlie loss of receptor-mediated functions, or be involved in augmentation of their biologic activity. The findings that important monocyte functions change under conditions of storage or culture have relevance to in vitro testing of various immune functions of monocytes performed clinically to monitor or guide therapy.
Binding of recombinant HIV coat protein gp120 to human monocytes.
Authors: Finbloom D S , Hoover D L , Meltzer M S 
Published: December 2022

Abstract
Inasmuch as the exact level of CD4 Ag expression on macrophages is controversial and because HIV may interact with macrophages in a manner different from that on T cells, we analyzed the binding of gp120 to freshly isolated and cultured monocytes. rgp120 was iodinated using the lactoperoxidase method to a sp. act. of 600 Ci/mmol. Highly purified monocytes (greater than 90%) were isolated from the leukapheresed blood of normal volunteers by Ficoll-Hypaque sedimentation followed by countercurrent centrifugal elutriation and cultured 7 days in DMEM supplemented with 1000 U/ml macrophage CSF in 10% human serum. Whereas MOLT/4 cells consistently bound freshly prepared 125I-rgp120 at 80% specificity with 5100 +/- 700 mol/cell, MCSF cultured monocytes bound rgp120 at only 0 to 20% specificity and 420 +/- 200 mol/cell. Most of the radioactivity bound by these cells could not be blocked by the addition of unlabeled rgp120. In contrast, the U937 myeloid cell line bound rgp120 with 50% specificity and about 2500 mol/cell. Whereas the antibody OKT4a (anti-CD4) blocked 80% of the binding on MOLT/4 cells and 50% on U937 cells, binding was only inhibited on the average of 6% on cultured monocytes. When soluble rCD4 was used as an inhibitor, binding to MOLT/4 cells was blocked by 80%. In contrast, binding to cultured monocytes was inhibited by 28%. HIV infectivity was blocked by similar concentrations of OKT4a. These observations suggest that although most binding of gp120 to cultured monocytes is not to the CD4 determinant, several hundred molecules do bind to a CD4-like molecule which promotes virus entry and replication.
Specific destruction of host-reactive mature T cells of donor origin prevents graft-versus-host disease in cyclophosphamide-induced tolerant mice.
Authors: Eto M , Mayumi H , Tomita Y , Yoshikai Y , Nishimura Y , Maeda T , Ando T , Nomoto K 
Published: December 2022

Abstract
In cyclophosphamide (CP)-induced tolerance, a long lasting skin allograft tolerance was established in many H-2-identical strain combinations without graft vs host disease. Destruction of donor-reactive T cells of host origin, followed by intrathymic clonal deletion of these cells, has been revealed to be the chief mechanisms of this system. Here, we studied the fate of host-reactive populations in donor-derived T cells of C3H/He (C3H) (H-2k, Mls-1b, Mls-2a) mice rendered CP-induced tolerant to AKR/J (AKR) (H-2k, Mls-1a, Mls-2b), by assessing AKR-derived Thy-1.1+ T cells bearing TCR V beta 3 that are specifically reactive with Mls-2a-encoded Ag of the recipient C3H mice. In the AKR-derived Thy-1.1+ lymph node cells of the C3H mice that had been treated with AKR spleen cells plus CP, CD4(+)-V beta 3+ T cells were obviously decreased by day 10 after the CP treatment. At this stage, the Thy-1.1+ T cells were not detected in the C3H thymus, suggesting that the obvious decrease of CD4(+)-V beta 3+ T cells of AKR origin was not due to intrathymic clonal deletion in the recipient C3H mice. Therefore, the destruction of the host-reactive mature T cells of donor origin, as well as that of the donor-reactive mature T cells of host origin, occurred by the CP treatment at the induction phase. Furthermore, after the establishment of intrathymic mixed chimerism in the recipient C3H mice, V beta 3+ T cells were not detected among the Thy-1.1+ T cells of AKR origin in the mixed chimeric thymus, suggesting that the host-reactive immature T cells repopulated from the injected donor hematopoietic cells were clonally deleted in the recipient thymus. These two mechanisms appear to prevent graft vs host disease in CP-induced tolerance.
Characterization of autoantibody-secreting B cells in mice undergoing stimulatory (chronic) graft-versus-host reactions. Identification of a CD44hi population that binds specifically to hyaluronate.
Authors: Murakami S , Miyake K , Abe R , Kincade P W , Hodes R J 
Published: December 2022

Abstract
This study was undertaken to identify and isolate the pathophysiologically important B cell subpopulation which is activated to Ig secretion and autoantibody production in stimulatory (chronic) graft-vs-host (GVH) reactions. We recently demonstrated that IL-5 stimulation in vitro induces the appearance of a distinct CD44hi Ialow CD45Rlow B cell subpopulation that has aquired the ability to bind to hyaluronate (HA), one of the ligands for CD44, and that this B cell subpopulation is enriched in both proliferative and Ig-secretory responses. In the present report, CD44 expression was examined in B cells which were activated in the course of stimulatory GVH reactions. Compared with normal mice, B cells from mice undergoing stimulatory GVH reactions contained a novel CD44hi B cell subpopulation which exhibited enhanced binding to HA. The CD44hi HA-adherent B cell subpopulation from GVH mice spontaneously secreted large amounts of Ig, particularly IgG, including autoantibody specific for ssDNA. These findings demonstrate that CD44 expression distinguishes those B cells that are activated in vivo in the course of GVH to proliferate and differentiate into Ig-secreting cells. These CD44hi, HA-adherent, cells may play a prominent role in the hypergammaglobulinemia and immune complex glomerulonephritis that occur during chronic GVH reactions.
Cytokine mRNA are preferentially increased relative to secretory granule protein mRNA in mouse bone marrow-derived mast cells that have undergone IgE-mediated activation and degranulation.
Authors: Gurish M F , Ghildyal N , Arm J , Austen K F , Avraham S , Reynolds D , Stevens R L 
Published: December 2022

Abstract
The levels of mRNA that encode a number of cytokines have been reported by several laboratories to be increased in mouse mast cells after their IgE-bearing receptors have been cross-linked with Ag. In this study, we have compared the mRNA levels for Fc epsilon RI alpha, three cytokines (IL-6, granulocyte-macrophage CSF, and TNF-alpha), actin and three secretory granule-localized proteins (carboxypeptidase A, proteoglycan peptide core, and a generic serine protease) in mouse bone marrow-derived mast cells (BMMC) before and after IgE-mediated activation and degranulation to determine the kinetics and specificity of mRNA induction. An antigen concentration of approximately 10 ng/ml was optimal for the release of histamine from IgE-sensitized BMMC and for the generation and release of a cytokine that was functionally and immunochemically identical to TNF-alpha. In kinetic experiments, the levels of TNF-alpha, IL-6, and granulocyte-macrophage CSF mRNA increased greater than 23-fold 0.5 to 1 h after activation. As assessed by in situ hybridization, virtually all BMMC contained detectable proteoglycan peptide core mRNA before and after exposure to Ag, but only approximately one-half of the Ag-treated cells in the culture contained IL-6 mRNA 1 h after activation. There was a slight transient increase at 4 h in the level of proteoglycan peptide core mRNA, but no increase in the levels of those highly expressed mRNA that encode actin, Fc epsilon RI alpha, carboxypeptidase A, and serine protease. Thus, despite the remarkable increment in the levels of the transcripts that encode cytokines in BMMC after IgE-mediated, Ag-dependent activation, the levels of those transcripts that encode a plasma membrane-localized recognition receptor and several constituents of the secretory granule remain essentially unchanged. The failure to increase substantially the level of protease and proteoglycan peptide core mRNA in mast cells after the activation/secretion response suggests that regranulation of mast cells is a slow process.