bluuebunny/crossref_metadata_2025 huggingface dataset:
The complement-inhibitory activity of CD59 resides in its capacity to block incorporation of C9 into membrane C5b-9.
Authors: Rollins S A , Sims P J
Published: January 2023

A human E membrane protein that inhibits lysis by the purified human C5b-9 proteins was isolated and characterized. After final purification, the protein migrated as an 18- to 20-kDa band by SDS-PAGE. Elution from gel slices and functional assay after SDS-PAGE (nonreduced) confirmed that all C5b-9 inhibitory activity of the purified protein resided in the 18- to 20-kDa band. Phosphatidylinositol-specific phospholipase C digestion of the purified protein abolished 50% of its C5b-9 inhibitory activity, and removed approximately 15% of the protein from human E. Western blots of normal and paroxysmal nocturnal hemoglobinuria E revealed an absence of the 18- to 20-kDa protein in the paroxysmal nocturnal hemoglobinuria E cells. The identity of this E protein with leukocyte Ag CD59 (P18, HRF20) was confirmed immunochemically and by N-terminal amino acid sequence analysis. A blocking antibody raised against the purified protein reacted with a single 18- to 20-kDa band on Western blots of human erythrocyte membranes. Prior incubation of human E with the F(ab) of this antibody increased subsequent lysis by the purified human C5b-9 proteins. Potentiation of C5b-9-mediated lysis was observed when erythrocytes were preincubated with this blocking antibody before C5b-9 assembly was initiated, or, when this antibody was added after 30 min, 0 degrees C incubation of C5b-8-treated E with C9. Chicken E incubated with purified CD59 were used to further characterize the mechanism of its C-inhibitory activity. Preincorporation of CD59 into these cells inhibited lysis by C5b-9, regardless of whether CD59 was added before or after assembly of the C5b-8 complex. When incorporated into the membrane, CD59 inhibited binding of 125I-C9 to membrane C5b-8 and reduced the extent of formation of SDS-resistant C9 polymer. The inhibitory effect of CD59 on 125I-C9 incorporation was most pronounced at near-saturating input of C9 (to C5b-8). By contrast, CD59 did not inhibit either C5b67 deposition onto the cell surface, or, binding of 125I-C8 to preassembled membrane C5b67. Taken together, these data suggest that CD59 exerts its C-inhibitory activity by limiting incorporation of multiple C9 into the membrane C5b-9 complex.
Determination of T cell epitopes on the S1 subunit of pertussis toxin.
Authors: Kim K J , McKinness S , Manclark C R
Published: January 2023

To understand the immunologic characteristics of pertussis toxin molecule and to explore the possibility of developing a synthetic vaccine, T cell epitopes on the enzymatic S1 subunit of pertussis toxin were studied by measuring the proliferative response of immune murine lymph node cells and T cell lines to Ag and to synthetic peptides. The maximum in vitro T cell proliferative response was obtained by stimulating immune lymphoid cells with 20 nM of the enzymatic S1 subunit. When the T cell proliferative response of murine lymphoid cells with different MHC backgrounds was tested, only mice bearing the H-2d haplotype were high responder to the S1 subunit. To determine T cell epitopes on the S1 subunit, the proliferative response of BALB/c immune lymphoid cells to several synthetic S1 peptides was measured. Only the peptide containing amino acid residues, 65-79, was recognized by BALB/c lymphoid cells and was confirmed to contain a T cell epitope by generating S1 specific BALB/c T cell line. By using this T cell line, the response of BALB/c mice to the S1 subunit as well as to peptide 65-79 was shown to be restricted to the I-Ad sublocus of class II Ag. Finally, we showed that lymph node cells of mice immunized with peptide 65-79 respond to the native S1 subunit.
Murine susceptibility to street rabies virus is unrelated to induction of host lymphoid depletion.
Authors: Perry L L , Hotchkiss J D , Lodmell D L
Published: January 2023

The mechanism and cellular targets of mononuclear cell depletion were investigated in strains of mice susceptible or resistant to lethal infection with a virulent street rabies virus (SRV). Significant depletion was evident in the thymus of all infected animals at approximately 5 days postinfection and subsequently involved the spleen and lymph nodes in mice developing clinical signs of rabies. Immunofluorescent analyses of lymphocyte subsets in depleted spleens revealed that cell losses were non-selective since the relative proportions of K+, Thy-1+, Lyt-1+, and Lyt-2+ cells remained unchanged. Diminished expression of I-A membrane glycoproteins on spleen lymphocytes was noted, however, perhaps reflecting reduced availability of I-A-inducing lymphokines. Adrenal hormone toxicity was identified as the cause of mononuclear cell depletion in that mice adrenalectomized before SRV infection showed no evidence of lymphoid depletion. The failure of adrenalectomy to alter anti-rabies antibody responses or SRV lethality also indicates that involution of the lymphoid system is a consequence and not a cause of genetically controlled host susceptibility to SRV. The mechanism of adrenal gland stimulation in rabies-infected mice appears to involve a virus-induced dysfunction in the pituitary gland rather than a stress response to paralysis-induced starvation, based on results of kinetic studies on weight loss, appetite depression, and paralysis in these animals and previous reports of pituitary infection during rabies disease. The relationship of these observations to current theories on rabies virus pathogenicity is discussed.
Lipopolysaccharide, but not IFN-gamma, down-regulates c-fms mRNA proto-oncogene expression in murine macrophages.
Authors: Gusella G L , Ayroldi E , Espinoza-Delgado I , Varesio L
Published: January 2023

In the present study we analyzed the effects of two macrophage activators, bacterial LPS and IFN-gamma, on the expression of the c-fms proto-oncogene in the immortalized murine macrophage cell line ANA-1. ANA-1 cells constitutively expressed significant levels of c-fms mRNA. LPS stimulation induced down-regulation of the expression of c-fms mRNA. In contrast, IFN-gamma did not change c-fms expression. Combined treatment of ANA-1 with IFN-gamma plus LPS resulted in a decrease in c-fms mRNA greater than that induced by LPS alone. Nuclear runoff experiments demonstrated that the down-regulation of c-fms mRNA by LPS or LPS plus IFN-gamma was controlled at a transcriptional level. Moreover, experiments in which c-fms mRNA expression was evaluated after the block of RNA or of protein synthesis did not reveal any difference in c-fms mRNA stability in LPS-treated and in untreated cells. These results demonstrate that LPS does not affect the stability of c-fms mRNA, but it decreases the transcription of the gene.
The murine complement receptor gene family. IV. Alternative splicing of Cr2 gene transcripts predicts two distinct gene products that share homologous domains with both human CR2 and CR1.
Authors: Kurtz C B , O'Toole E , Christensen S M , Weis J H
Published: January 2023

The murine Cr2 gene encodes at least two related proteins. The first of these is predicted to include 1408 amino acids from a transcript including 4224 coding nucleotides. This protein is predicted to contain 21 60-amino acid repeats plus those residues encoding transmembrane and cytoplasmic regions for a total peptide m.w. of 155,307. The first six of these repeats are similar to human CR1 in sequence and organization. The second protein is encoded by an alternatively spliced Cr2 transcript that is lacking those sequences which encode the first six 60-amino acid repeats of the larger protein. This second, smaller protein, encoded by a transcript of 3096 coding nucleotides, is predicted to include 15 60-amino acid repeats, plus the transmembrane and cytoplasmic regions. This smaller protein contains 1032 amino acids for a peptide m.w. of 113,328. This second protein is extremely homologous in size and sequence to human CR2. Both proteins share the same signal sequence for membrane insertion. DNA sequence analysis, RNA protection studies and genomic phage mapping indicate the transcripts which encode these proteins are derived from the Cr2 gene via alternative splicing.
Nuclear events after activation of CD4+8+ thymocytes.
Authors: Riegel J S , Richie E R , Allison J P
Published: January 2023

Functionally mature T cells respond to stimulation via the Ag receptor by secretion of IL-2 and/or other lymphokines and by proliferation. However, immature CD4+8+ thymocytes do not secrete IL-2 or proliferate in response to stimulation. We have analyzed murine thymocyte populations enriched for CD4+ and CD4+8+ cells as well as the functionally mature CD4+ lymphoma C6VL-B and the CD4+8+ lymphoma 1010 for their ability to express mRNA related to early products of T cell activation signals. When stimulated with the calcium ionophore (Ionomycin) plus PMA, all the cells, regardless of their phenotype, accumulated abundant levels of c-myc mRNA. However, in contrast to the CD4+ thymocytes and C6VL-B, which accumulated abundant levels of IL-2 transcripts, neither the normal CD4+8+ thymocytes nor 1010 expressed IL-2 mRNA before or after stimulation. We have also examined these cells for the presence of the murine equivalents of two nuclear DNA-binding factors, NFAT-1 and NFIL2-A, which have been shown to be involved in IL-2 gene expression in human T cells. Our results indicate: 1) NFIL-2A binding activity is constitutively expressed in both CD4+ and CD4+8+ thymocytes and lymphomas and 2) NFAT-1 binding activity is readily detected in CD4+ thymocytes and C6VL-B, but is detected in very minimal amounts in populations enriched for CD4+8+ thymocytes and in 1010 upon activation. These results suggest that the failure of CD4+8+ thymocytes to express IL-2 mRNA upon stimulation may be in part due to the lack of inducibility of NFAT-1 binding activity, and that functional maturation of this population might be associated with acquisition of the ability to induce NFAT-1 activity.
IFN-alpha and IFN-gamma can affect both monocytes and tumor cells to modulate monocyte-mediated cytotoxicity.
Authors: Webb D S , Gerrard T L
Published: January 2023

IFN-alpha and IFN-gamma were found to enhance monocyte-mediated activity by acting on both tumor cells and monocytes. The addition of IFN-alpha or IFN-gamma enhanced the monocyte-mediated cytotoxicity of the human melanoma cell line, A375, as well as the human colon carcinoma cell line, HT-29. However, IFN-alpha generally induced more monocyte-mediated lysis of the A375 cells, whereas IFN-gamma induced more monocyte-mediated lysis of the HT-29 cells. These differences are, in part, due to the direct effects of the IFN on the tumor cells. Pretreatment of A375 cells with either IFN-alpha or IFN-gamma significantly enhanced their susceptibility to lysis by untreated monocytes. However, only IFN-gamma pretreatment of HT-29 cells enhanced the lysis of these cells by untreated monocytes. Differences were also observed in the activation of monocytes by IFN-alpha vs IFN-gamma with respect to their ability to induce soluble cytotoxic factors. We found that the addition of IFN-gamma and tumor cells (either the A375 or HT-29 cells) to monocytes induced TNF release, whereas IFN-alpha or IFN-gamma alone or IFN-alpha and tumor cells had no effect. Despite its presence, TNF did not appear to play a major role in the killing of either tumor cell line. However, inhibitors of H2O2-myeloperoxidase system suppressed both IFN-alpha- and IFN-gamma-induced cytotoxicity of the HT-29 cells. Thus IFN-alpha and IFN-gamma can induce both similar and distinct mechanisms of cytotoxicity in monocytes. In addition, both IFN types can increase the susceptibility of tumor cells to lysis by untreated monocytes, although sensitivity to IFN-alpha vs IFN-gamma may vary with different tumor cell lines. These differences observed between IFN-alpha and IFN-gamma on monocytes and tumor cells could have important implications for the clinical use of these cytokines.
Generation of neutralization-resistant HIV-1 in vitro due to amino acid interchanges of third hypervariable env region.
Authors: Masuda T , Matsushita S , Kuroda M J , Kannagi M , Takatsuki K , Harada S
Published: January 2023

Antigenic mutants of HIV-1 were isolated from three plaque-cloned viruses by the resistance of the virus to neutralizing mAb 0.5 beta against V3 domain of viral gp120, when the viruses were passaged in the presence of the antibody. However, when chronically infected MOLT-4 cells were treated with 0.5 beta mAb, recovered viruses from the 0.5 beta-treated cells showed no antigenic changes. The extent of genomic variation among antigenically distinct isolates was examined by nucleotide sequencing, which revealed a few base substitutions in 0.5 beta-binding site of all mutants isolated. The predicted amino acid replacements within 0.5 beta reacting epitope (V3 domain) causing the altered antigenicity were also identified for each of three isolates. Particularly, in one of the mutants, the most conserved Gly-Pro-Gly-Arg region located at the center of the V3 domain was changed to Gly-Gln-Gly-Arg. The radioimmunoprecipitation and synthetic peptide analyses revealed that this Pro320----Gln substitution reduced the binding affinity with 0.5 beta, although other mutations observed in the other mutants did not affect the binding affinity in radioimmunoprecipitation. We also observed that nucleic acid substitutions in the V3 domain occurred frequently in the absence of 0.5 beta mAb during our in vitro acute infection system using MT-4 cells.
Inhibition of murine monocyte proliferation by a colony-stimulating factor-1 antisense oligodeoxynucleotide. Evidence for autocrine regulation.
Authors: Birchenall-Roberts M C , Ferrer C , Ferris D , Falk L A , Kasper J , White G , Ruscetti F W
Published: January 2023

Using a combination of v-myc and v-ras oncogenes, we have established a growth factor-independent monocyte cell line from murine fetal liver (FL-ras/myc). Biologic and molecular characterization demonstrated that the gene for the macrophage growth factor CSF-1 and the c-fms proto-oncogene (CSF-1 receptor) are expressed in this cell line, thus suggesting autocrine regulation as a possible mechanism for the unregulated growth of these cells. To study this possibility, we used 1) mAb, to neutralize the CSF-1 protein produced by the cell line, and 2) antisense oligomers, to inhibit CSF-1 gene products by specific base-pairing of complementary nucleic acids. We report here that both approaches inhibited in vitro cell growth by 60 to 70%, whereas the combination of oligomer and mAb inhibited proliferation by 95%. However, control antisense oligomers (50% bp mismatch with CSF-1 mRNA) did not inhibit FL-ras/myc cell growth. Furthermore, the inhibitory effects of mAb and oligomers were reversible when they were removed from the media. Detection of cell-associated CSF-1 protein by immunofluorescence showed that cells treated with the antisense oligomer expressed significantly less CSF-1 protein. These results indicate that the FL-ras/myc cell line requires CSF-1 for autonomous growth and that oligomers can efficiently block production of autocrine growth factors.
IL-6 is produced by osteoblasts and induces bone resorption.
Authors: Ishimi Y , Miyaura C , Jin C H , Akatsu T , Abe E , Nakamura Y , Yamaguchi A , Yoshiki S , Matsuda T , Hirano T
Published: January 2023

To examine the possible involvement of IL-6 in bone metabolism, a mouse osteoblastic cell line (MC3T3-E1) and primary osteoblast-like cells from fetal mouse calvaria were cultured with several systemic and local bone-resorbing agents and their expression of IL-6 mRNA was determined. Local bone-resorbing agents such as IL-1 alpha, IL-1 beta, TNF-alpha, and LPS greatly induced IL-6 mRNA expression in both MC3T3-E1 cells and primary osteoblast-like cells. Parathyroid hormone slightly increased expression of IL-6 mRNA in primary osteoblast-like cells but not in MC3T3-E1 cells. Neither IL-6 nor 1 alpha,25-dihydroxyvitamin D3 increased expression of IL-6 mRNA in either of the osteoblast-like cells. In agreement with the expression of IL-6 mRNA, biologically active IL-6 was produced in response to the treatment with IL-1 alpha, TNF-alpha, and LPS in MC3T3-E1 cells. Adding IL-6 dose dependently stimulated the release of 45Ca from prelabeled fetal mouse calvaria. Simultaneously adding suboptimal concentrations of IL-6 and IL-1 alpha induced bone resorption cooperatively. In accord with the increase in the release of 45Ca by IL-6, there were three times as many osteoclasts in the bone sections of calvaria cultured with IL-6 for 5 days as in the controls. IL-6 slightly suppressed alkaline phosphatase activity and collagen synthesis in MC3T3-E1 cells. These results indicate that IL-6 is also produced by osteoblasts, preferentially in response to local bone-resorbing agents, and it induces bone resorption both alone and in concert with other bone-resorbing agents.
Monosodium urate crystals stimulate phospholipase A2 enzyme activities and the synthesis of a phospholipase A2-activating protein.
Authors: Bomalaski J S , Baker D G , Brophy L M , Clark M A
Published: January 2023

Eicosanoids are important mediators of the inflammatory response to monosodium urate crystals (MSUC) that results in gout. Phospholipase enzymes cleave fatty acids from membrane phospholipids, and this is thought to be the rate-limiting step in eicosanoid production. To understand better the mechanism of eicosanoid production in this disease, we stimulated human peripheral blood neutrophils and monocytes with MSUC and measured phospholipase enzyme activities. MSUC stimulated both intracellular and secretory phospholipase A2 enzyme activities in a time and concentration-dependent manner. Specificity was observed, as phospholipase C activities were not affected. Pretreatment with colchicine, but not aspirin, indomethacin, allopurinol, or islet activating protein, abrogated the enhanced phospholipase A2 activities. We have recently isolated and characterized a phospholipase A2 activating protein termed PLAP from synovial fluid from patients with rheumatoid arthritis, and from murine and bovine cell lines. PLAP was detected in gouty synovial fluid by immunodot blotting and ELISA assays and expressed the same characteristics as PLAP identified from other sources. To examine the role of PLAP in MSUC-induced phospholipase A2 stimulation, we treated cells with MSUC and observed an increase in immunoreactive PLAP. This response also could be blunted by colchicine, but not other drugs. Both phospholipase A2 and PLAP induced production by human monocytes of PGE2 and leukotriene B4 by neutrophils. These findings suggest that phospholipase A2 activation in response to MSUC requires an intact microtubule structure, and that phospholipase A2 and PLAP may be important modulators of at least a portion of the gouty inflammatory response.
Developmental expression of plasminogen activator inhibitor type 1 by human alveolar macrophages. Possible role in lung injury.
Authors: Chapman H A , Yang X L , Sailor L Z , Sugarbaker D J
Published: January 2023

Urokinase activity is regulated by the specific endogenous plasminogen activator inhibitors type 1 (PAI-1) and type 2 (PAI-2). One of these inhibitors, PAI-1, has been directly implicated in connective tissue metabolism by virtue of its ability to bind extracellular matrix proteins. Because the normal lung is relatively rich in urokinase and abnormalities in urokinase activity have been associated with fibrotic lung diseases, we have explored the possibility of local production of PAI-1 and PAI-2 in human lung. Reverse transcription and subsequent amplification by the polymerase chain reaction of total lung RNA revealed PAI-1 mRNA in each of three normal samples and in two specimens from patients with the adult respiratory distress syndrome (ARDS). In situ hybridizations of lung biopsy specimens from a patient with ARDS with cRNA probes to PAI-1 and PAI-2 indicated that alveolar macrophages express PAI-1 mRNA during the acute injury phase. Subsequent reverse transcription and PCR amplification of normal human monocyte and alveolar macrophage mRNA revealed that neither cell type expressed mRNA for urokinase inhibitors. However, after 24 h stimulation with endotoxin in vitro, monocytes were strongly positive for PAI-2 but negative for PAI-1 mRNA whereas, under the same conditions, alveolar macrophages exhibited mRNA for both PAI-1 and PAI-2. Metabolic labeling of endotoxin-stimulated alveolar macrophages with 35S-methionine followed by immunoprecipitation with PAI-1 and PAI-2 antibodies revealed that macrophages synthesized both PAI-1 and PAI-2. As judged by immunoprecipitation and functional studies, PAI-2 was found to be the major intracellular PA inhibitor whereas PAI-1 was found to predominate outside the cell. Thus, mononuclear phagocytes exhibit a developmental potential for PAI-1 expression. The release of PAI-1 by stimulated macrophages, as observed in the setting of ARDS, may be one mechanism by which these cells promote connective tissue accumulation.
Leukotriene B4 potentiates the expression and release of Fc epsilon RII/CD23, and proliferation and differentiation of human B lymphocytes induced by IL-4.
Authors: Dugas B , Paul-Eugene N , Cairns J , Gordon J , Calenda A , Mencia-Huerta J M , Braquet P
Published: January 2023

This study documents the influence of leukotriene (LT) B4 on human B lymphocyte responses. Incubation of freshly isolated B lymphocytes with LTB4, but not LTC4, induced a slight but significant, time- and dose-dependent increase in the surface expression of Fc epsilon RII/CD23 and class II MHC Ag and in the release of soluble CD23. These changes were maximal at 10 nM LTB4 after an incubation period of 48 h. When B lymphocytes were preactivated in vitro with Staphylococcus aureus Cowan strain I (SAC), neither LTB4 nor LTC4 was able to promote proliferation and/or IgG and IgM secretion. In contrast, when resting B lymphocytes were stimulated with a suboptimal concentration (3 U/ml) of IL-4, LTB4, but not LTC4, potentiated both the Fc epsilon RII/CD23 and the class II MHC antigen expression, and the release of soluble CD23 in a dose-dependent manner, without affecting the kinetics of these responses. Furthermore, LTB4, but not LTC4, amplified both the proliferative response and the IgG and IgM secretion induced by addition of a suboptimal dose of IL-4 (3 U/ml) to SAC-preactivated B lymphocytes. Again, LTB4 did not modify the kinetics of the proliferative response promoted by IL-4. Although LTB4 potentiated IL-4-induced IgG and IgM secretion from SAC-activated B lymphocytes, no production of IgE was observed. These data indicate that LTB4 could play a regulatory role in the modulation of IL-4-induced signaling in human B lymphocytes.
Maturation-related changes in the expression of Fc gamma RII and Fc gamma RIII on mouse mast cells derived in vitro and in vivo.
Authors: Katz H R , Arm J P , Benson A C , Austen K F
Published: January 2023

The expression and function of Fc gamma RII and Fc gamma RIII on three mouse mast cell populations that differ in maturity as assessed by secretory granule constituents were analyzed by cellular and immunochemical approaches. As quantified by flow cytometric analysis of the binding of the rat 2.4G2 anti-Fc gamma RII/III mAb, mouse serosal mast cells (SMC) purified from the peritoneal cavity expressed more receptors per cell than did mouse IL-3-dependent, bone marrow culture-derived mast cells (BMMC), which are progenitors of SMC. Coculture of BMMC with mouse 3T3 fibroblasts for 2 wk, which alters the secretory granule composition toward that of SMC, also increased receptor epitope expression to a level equivalent to that of SMC. As assessed by rosette assays with mouse mAb to SRBC, all three mast cell populations bound IgG1, IgG2a, and IgG2b, essentially all binding was inhibited by 2.4G2 antibody, and greater quantities of the antibody were required to block immune adherence by cocultured mast cells and SMC as compared with BMMC. Immunoprecipitation and SDS-PAGE analysis of Fc gamma RII and Fc gamma RIII from BMMC, cocultured mast cells, and SMC that were surface radiolabeled with Na125I revealed predominant native forms of 62, 57, and 56 kDa, respectively, and an additional surface form of 43 kDa in SMC. Removal of N-linked carbohydrate from immunoprecipitates demonstrated that BMMC expressed peptide cores of 38 kDa (Fc gamma RII-1 gene product) and 31 kDa (Fc gamma RII-2 gene product), and barely detectable amounts of a 28-kDa (Fc gamma RIII gene product) core. The expression of all three was increased by coculture with 3T3 fibroblasts, consistent with the increased expression of their common epitope by cytofluorographic analysis. SMC expressed primarily the Fc gamma RII-1 and some Fc gamma RIII gene product. Thus, the three populations of mast cells express different amounts and ratios of the Fc gamma RII and Fc gamma RIII gene products, and maturation of BMMC during coculture with fibroblasts in vitro and in the peritoneal cavity in vivo augments cell-surface expression of the receptors and immune adherence function.
Failure to detect IL-3-binding sites on human mast cells.
Authors: Valent P , Besemer J , Sillaber C , Butterfield J H , Eher R , Majdic O , Kishi K , Klepetko W , Eckersberger F , Lechner K
Published: January 2023

IL-3, a pleiotropic lymphokine, has been termed mast cell growth factor because it promotes growth and differentiation of murine mast cells. Murine mast cells, in turn, express cell surface receptors for IL-3. Human rIL-3 has been shown to induce proliferation and differentiation of human basophils and to activate basophils via high affinity binding sites. To investigate whether human mast cells express IL-3R, binding studies with 125I-radiolabeled human rIL-3 were performed on HMC-1, a novel human mast cell line, and on pure populations (i.e., 93 to 99% purity) of human tissue mast cells obtained with mAb and C from dispersed lung (n = 2). Unexpectedly, neither enriched human lung mast cells nor HMC-1 cells bound radiolabeled human rIL-3 specifically. Moreover, human rIL-3 failed to promote uptake of [3H]thymidine, synthesis of histamine, histamine releasability, or changes in expression of mast cell differentiation Ag (YB5B8, CD54/ICAM-1, CD9/p24, CD33/gp67) on either human lung mast cells or HMC-1 cells. It is hypothesized that the fundamental difference in the biologic response to IL-3 between human and murine mast cells is due to a loss during evolution of mast cell high affinity IL-3 binding sites.
Class I MHC genes and CD8+ T cells determine cyst number in Toxoplasma gondii infection.
Authors: Brown C R , McLeod R
Published: January 2023

To determine roles of MHC class I and II genes in protection against Toxoplasma gondii, H-2 congenic and mutant mice were infected perorally with bradyzoites of T. gondii and brain cysts were enumerated 30 days later. As B10 mice (H-2b) are cyst susceptible and B10.A mice (H-2a) are cyst resistant, B10 congenic mice having the same alleles but different H-2 haplotypes were used to locate the controlling gene. Genes located at H-2L (i.e., class I genes) were found to regulate the number of brain cysts which form following peroral infection with T. gondii (p less than 0.001) with Ld being resistant and Lb being susceptible. The regulatory function of the H-2L gene product was confirmed through the study of D mutant (dm) mice. B10.D2-H-2dm1 (dm1) mice have a gain-loss mutation in Dd and Ld (i.e., recombination of Ld and Dd) and BALB/c-H-2dm2 (dm2) mice have a deletion of the Ld gene. Both these dm strains were cyst susceptible (p less than 0.001). These results provide the first direct evidence that class I genes regulate numbers of T. gondii cysts that form. In vivo ablation of CD8+ T cells with mAb YTS 169.4 converted cyst resistant B10.BAR12 mice to cyst susceptible. This result is consistent with a role for MHC restricted CD8+ cytotoxic (or suppressor) T cell regulation of cyst formation. A mutation in Ia in B6.C-H-2bm12 (bm12) mice amplified cyst numbers in susceptible mice, which is consistent with the importance of helper/inducer T cells in the induction of cytotoxic T cells. These findings are relevant to understanding the complex immunologic mechanisms that protect against T. gondii infection, development of protective preparations, and provide a conceptual basis for determining whether similar immunogenetic regulation of susceptibility is also operative in humans.
cDNA sequences encoding rabbit latent kappa 1 b5 and b6 Ig L chains.
Authors: Ishaq M , Wolf B , Dreher K
Published: January 2023

Regulation of rabbit Ig C kappa 1 L chain gene expression is thought to be under allelic control. Four nominal allotypic variants designated b4, b5, b6, and b9 have been found to be co-dominantly expressed at the C kappa 1 gene locus. Latent allotypes are nonallelic and appear as unexpected and transitory molecules in the serum as well as on B cell surfaces. To determine the mechanism of latent kappa 1 allotype expression, rabbits were initially induced to produce latent b5 and b6 allotypes by infection with Trypanosoma brucei and RNA was extracted from the lymph nodes of these rabbits. The polymerase chain reaction using allele specific oligonucleotide primers was used to detect and amplify the mRNA encoding the latent b5 and b6 sequences. Nucleotide sequence analysis of the cloned products revealed that the latent b5 and b6 cDNA sequences were identical to their nominal allelic counterparts, b5 and b6, respectively. Thus, the identification of transcripts encoding latent b5 and b6 sequences rules out serologic artifacts and idiotypic mimicry as explanations of latent allotype expression.
Isolation of a novel tumor protein that induces resistance to natural killer cell lysis.
Authors: Serrano R , Yiangos Y G , Solana R , Sachs J A , Pena J
Published: January 2023

The human metastatic tumor cell line CAP-2, produces a soluble factor that induces resistance to NK lysis of K-562 susceptible leukemia cell line, and does not inhibit the cytotoxic capacity of effector cells. The use of sequential HPLC, hydrophobic interaction chromatography, and reverse phase chromatography, coupled with cytotoxic assays, resulted in the isolation and separation to homogeneity of a novel protein responsible for this biologic activity. Size estimation studies based on TSK HPLC columns showed that this protein has a mass of 8 to 12 kDa. The amino acid composition analysis of the CAP-2 protein calculated from HPLC chromatograms shows that this protein contains around 108 amino acids. Subsequent gas phase sequence analysis, however, was hampered because the N terminus of this protein was blocked and therefore unsuitable for sequencing by Edman degradation. The functional studies showed that the NK lysis-resistance activity of the CAP-2 protein is mediated by interaction with and nonspecific binding to NK target cells. The lymphokine-activated killer and macrophage-mediated cytotoxicity and mitogen-induced proliferation is not affected. Unexpectedly, the CAP-2 protein appears to be mitogenic to its own cell line. Thus, the induction of NK lysis-resistance and the mitogenic activity showed by CAP-2 protein could contribute to the tumor growth and metastatic establishment.
Complete dissection of the Hb(64-76) determinant using T helper 1, T helper 2 clones, and T cell hybridomas.
Authors: Evavold B D , Williams S G , Hsu B L , Buus S , Allen P M
Published: January 2023

We have generated cloned Th1 cells, Th2 cells, and T cell hybridomas specific for the single immunogenic peptide from the beta-chain of murine hemoglobin (Hb(64-76)). The availability of these various types of T cells provided us an unique opportunity to examine and dissect the T cell response to an immunogenic peptide. A panel of altered Hb peptides was made by replacing each amino acid in the Hb peptide (positions 64-76) with a conservative amino acid substitution or an alanine. Although none of the eleven T cell clones and hybridomas tested exhibited the same pattern of reactivity to the substituted Hb peptides, some general features were identified for all T cell responses. The primary T cell contact residue of Hb(64-76) was shown to be asparagine 72. For every Hb(64-76) specific T cell, no activation was observed using a peptide containing the conservative substitution of a glutamine for the asparagine at position 72. The flanking glutamic acid at position 73 was also required for a proliferative response for all of the Th1 and Th2 clones. The Th subtypes were not grossly unique in their responses to the substituted Hb peptides, but exhibited minor differences in fine specificity with the Th1 cells identifying more critical amino acids then did the Th2 cells. For the Th1 cells and also the T cell hybridomas, the phenylalanine at position 71 was critical for a T cell response. Analysis of peptide affinity for IEk molecules indicated that position 71 played a role in peptide binding to MHC. Secondary T cell contact residues, which were important for many but not all of the T cells, were identified at positions 69, 70, and 76. Overall T cell responses were minimally affected by changes in the amino acid residues at positions 64-68, 74, and 75. We have also demonstrated that cloned Th1 cells, Th2 cells and T hybridomas can be generated against the same Hb(64-76) determinant.
Uncoupling of cytokine mRNA expression and protein secretion during the induction phase of T cell anergy.
Authors: Schall T J , O'Hehir R E , Goeddel D V , Lamb J R
Published: January 2023

The CD4+ T cell clone HA1.7 may be made specifically nonresponsive, or anergic, to its cognate Ag, an influenza hemagglutinin peptide (HA), by pretreatment with the superantigen Staphylococcus aureus enterotoxin B or with high concentrations of HA itself. We compare the patterns of mRNA expression and protein production of selected T cell cytokines during the first 24 h after treatments that induce anergy in HA1.7 and during the same period after treatments that simulate normal cellular activation. The cytokines examined include TNF-alpha, IL-8/neutrophil activating protein-1 and the RANTES/SIS cytokines, a family of small secreted proteins with inflammatory and potential antiproliferative and leukocyte regulating activities. Messenger RNA for TNF-alpha, human MIP-1 alpha, human MIP-1 beta, and IL-8 are all induced during the development of clonal anergy in HA1.7, and these levels are significantly higher than those seen during activation of the clone using an anti-CD3 antibody and IL-2. These high levels of mRNA also persist longer than those seen after anti-CD3 and IL-2 activation. However, the increased levels of mRNA are not typically accompanied by increased protein secretion. In all cases but one, the amount of cytokine secreted by HA1.7 cells was greater after anti-CD3 and IL-2 treatments than after anergy-inducing treatments. Thus, the induction of T cell anergy in HA1.7 does not appear to require a general inhibition of T cell cytokine mRNA expression, and, in fact, anergy treatments appear to superinduce certain cytokine transcripts, but anergy-specific posttranscriptional mechanisms may exist by which cytokine release is regulated.
HLA-DR2, [HLA-B7, SC31, DR2], and [HLA-B8, SC01, DR3] haplotypes distinguish subjects with asthma from those with rhinitis only in ragweed pollen allergy.
Authors: Blumenthal M , Marcus-Bagley D , Awdeh Z , Johnson B , Yunis E J , Alper C A
Published: January 2023

MHC haplotypes were determined for 52 patients with ragweed pollen allergy, with and without asthma, and 27 non-atopic controls. Total IgE levels were unimodally distributed in all study groups and were higher in atopic patients in general compared with non-atopics. There was no difference in total IgE levels in patients with rhinitis only compared with those with rhinitis and asthma. IgE anti-Amb a V was detected (after subtraction of values representing the means + 2 SD of the non-atopics) in 9 of 20 asthmatics but only 3 of 32 patients with only rhinitis and was thus associated with asthma. Mean anti-Amb a V was much higher in the antibody-positive asthmatics (1710 U/ml) than in the positive patients with rhinitis only (469 U/ml). The extended MHC haplotype [HLA-B7, SC31, DR2] and its possible DR-containing fragment (SC31, DR2), were found almost exclusively among the patients with IgE anti-Amb a V and were significantly elevated in patients with asthma. DR2 in general, but not DR2 without SC31, was significantly increased in frequency in patients with anti-Amb a V. In contrast, the extended haplotype [HLA-B8, SC01, DR3] and DR3 in general were increased among patients with rhinitis only and patients without IgE anti-Amb a V compared with general controls. Thus, [HLA-B8, SC01, DR3] and DR3 appear to be "protective" for the production of this antibody and the occurrence of asthma. The findings are consistent with an MHC-linked gene or genes on [HLA-B7, SC31, DR2] (but not necessarily DR2, Dw2, or DQw6 in general) controlling the IgE immune response to Amb a V and associated with asthma in ragweed pollen-sensitive subjects. In patients with rhinitis alone and generally undetectable levels of IgE anti-Amb a V, the increase in [HLA-B8, SC01, DR3] and DR3 may mark a response to an as yet unidentified Ag associated with ragweed allergy and rhinitis only.
Induction of IFN-alpha in peripheral blood mononuclear cells by HIV-infected monocytes. Restricted antiviral activity of the HIV-induced IFN.
Authors: Gendelman H E , Baca L M , Kubrak C A , Genis P , Burrous S , Friedman R M , Jacobs D , Meltzer M S
Published: January 2023

PBMC cocultured with HIV-infected monocytes for 12 to 48 h released high levels of IFN activity. IFN titers were directly dependent upon time after virus infection and level of HIV replication in infected cells. IFN induction in PBMC was evident with HIV-infected monocytes and PBMC and with myeloid and lymphoblastoid cell lines with at least three different HIV strains. In HIV-infected cell line pairs in which virus infection occurs in both productive and restricted forms, IFN induction in PBMC occurred only with productive infection. IFN activity was acid stable and completely neutralized by antibodies against IFN-alpha. Induction of IFN required cell-cell contact between HIV-infected cells and PBMC, but was independent of MHC compatibility. With PBMC co-cultured with autologous HIV-infected monocytes, IFN induction was highly selective: IL-1 beta, IL-6, or TNF-alpha activity and mRNA were not detected. Cell surface determinants on HIV-infected monocytes that induced IFN in PBMC remained active after fixation in 4% paraformaldehyde. Both adherent and nonadherent PBMC produced IFN after coculture with HIV-infected monocytes. Ability to produce IFN by PBMC was not affected by depletion of T cell, NK cell, B cell, or monocyte subpopulations. The IFN activity produced by PBMC cocultured with HIV-infected cells was about 20-fold less active than equal quantities of rIFN-alpha 2b for inhibition of HIV replication in monocytes and at low concentrations enhanced virus growth. Clinical studies with HIV-infected patients and parallel findings in animal lentivirus disease suggest an adverse role for IFN in disease progression. Conditions for induction of IFN in the culture system described in this report may mimic those in the HIV-infected patient. Defining the molecular basis for IFN induction, the cells that produce IFN, and the altered biologic activity of this important cytokine may provide insight into the pathogenesis of HIV disease.
Protection from experimental autoimmune thyroiditis conferred by a monoclonal antibody to T cell receptor from a cytotoxic hybridoma specific for thyroglobulin.
Authors: Texier B , Bedin C , Roubaty C , Brezin C , Charreire J
Published: January 2023

A clonotypic mAb, AG7, has been prepared from splenocytes of CBA/J mice immunized with a cytotoxic T cell hybridoma, HTC2, specific for a pathogenic epitope of the thyroglobulin molecule in association with class I MHC Ag. AG7 binds to HTC2 cells but not to the other T cell hybridomas tested. Moreover, when used in functional studies, AG7 blocks the HTC2 capacity of specific target lysis. It also reacts with a determinant that comodulates with the CD3 Ag present on the surface of HTC2 cells. Immunoprecipitation of 125I-labeled solubilized HTC2 membranes demonstrated two bands located at 90 and 72 kDa under nonreducing conditions, which became a 46-kDa band under reducing conditions. Finally, when AG7 is injected into CBA/J mice, on day -1 before immunization with the pathogenic tryptic fragments of the thyroglobulin molecule, experimental autoimmune thyroiditis is abrogated. Thus, one of the multiple potential mechanisms of the protective immunity against EAT induced by HTC2 cells that we previously proposed, i.e., the generation of anti-clonotypic antibodies to HTC2 TCR, seems apparent.
Cartilage and joint inflammation. Regulation of IL-8 expression by human articular chondrocytes.
Authors: Lotz M , Terkeltaub R , Villiger P M
Published: January 2023

Injury to cartilage is a recognized sequela of neutrophil activation in arthritic joints. This study examined the possibility that chondrocytes may play a direct role in intraarticular neutrophil activation. We demonstrate that IL-1 beta-stimulated primary and subcultured human articular chondrocytes, express the gene for the potent neutrophil chemotactic and activating cytokine, IL-8. Expression of IL-8 mRNA is also inducible by TNF-alpha and LPS and, to a lesser degree, by the chondrocyte growth factor, transforming growth factor-beta, but not by platelet-derived growth factor, acidic and basic fibroblast growth factor, or epidermal growth factor. Analysis of IL-1 beta-stimulated cartilage organ cultures by in situ hybridization demonstrates that chondrocytes in all zones of cartilage are rapidly induced to express the IL-8 gene in high copy number. Metabolically labeled IL-1 beta-stimulated chondrocytes synthesize IL-8 de novo, which comigrates on SDS-PAGE with IL-8 produced by synovial fibroblasts. Furthermore, the conditioned media of IL-1 beta-stimulated chondrocytes and cartilage organ cultures contain neutrophil chemotactic activity which is completely neutralized by a specific antibody to IL-8, establishing that a bioactive form of IL-8 is the major secreted neutrophil chemotactic factor. By using a specific RIA, we demonstrate that not only IL-1 beta, but also TNF-alpha and LPS can induce abundant IL-8 secretion from chondrocytes. In conclusion, articular chondrocytes are readily inducible to express the IL-8 gene and secrete biologically active IL-8 which can promote neutrophil-mediated inflammation and cartilage destruction.
Transforming growth factor-beta in synovial fluids modulates Fc gamma RII (CD16) expression on mononuclear phagocytes.
Authors: Wahl S M , Allen J B , Welch G R , Wong H L
Published: January 2023

Mononuclear phagocytes in the synovium of patients with arthritis, in contrast to blood monocytes, were found to express a third receptor for the constant region of Ig (Fc gamma RIII), in addition to Fc gamma RI and Fc gamma RII. Previously identified on mature mononuclear phagocytes or phagocytes exposed to transforming growth factor-beta (TGF-beta) in vitro, this study documents the presence of Fc gamma RIII (CD16) expressing cells at an inflammatory site. Furthermore, the presence of CD16 on the majority of the LeuM3 (CD14) positive synovial monocytic cells could be mimicked by exposing blood monocytes to synovial fluids from patients with rheumatoid arthritis (17 of 19) and synovial fluids from patients with osteoarthritis (4 of 4). In additional studies, the soluble factor in inflammatory synovial fluids responsible for regulating CD16 expression was found to be consistent with the presence of TGF-beta. Inhibition of the activity in synovial fluids with a neutralizing antibody to TGF-beta confirmed a role for this peptide in synovial phagocytic cell CD16 expression. Moreover, signal transduction through CD16 on synovial phagocytes resulted in augmented extracellular release of superoxide anion that may contribute to tissue damage and other inflammatory sequelae. Identification of TGF-beta and its association with upregulation of CD16 at sites of chronic inflammation may provide insight into the destructive lesions associated with inflammatory arthropathies.
Experimental analysis by site-directed mutagenesis of somatic mutation effects on affinity and fine specificity in antibodies specific for lysozyme.
Authors: Lavoie T B , Drohan W N , Smith-Gill S J
Published: January 2023

To experimentally examine the functional roles of somatically derived structural variation in the lysozyme-binding mAb HyHEL-10, we have introduced three different point mutations and one insertion at two different sites in HyHEL-10 by site-directed mutagenesis and expression of the mutant antibodies. Mutation of Asp----Ala at position 101 of the H chain returns a somatically mutated residue to its germline sequence for HyHEL-10, and reduces affinity for chicken lysozyme by approximately 9000-fold. Lengthening the third H chain hypervariable region by two amino acids reduces affinity by about 2000-fold. Two mutations, Asp----Thr at position 101 in the H chain and Lys----Thr at position 49 in the L chain, model somatic differences found in another structurally related but functionally distinguishable mAb and minimally decrease affinity for chicken lysozyme. The H chain mutation Asp101VVH----Thr has little effect on affinity for other avian lysozymes but does alter relative fine specificity for these lysozymes. The L chain mutation Lys49VK----Thr increases affinity for duck lysozyme by approximately fivefold. Neither of the positions mutated, 101 in the H chain nor 49 in the L chain, nor the residues near the insertion contact lysozyme in the x-ray structure of the HyHEL-10 F(ab)-HEL complex. The results suggest that these mutations, which model observed somatic mutations, produce functional variation by indirect or long-range effects.
Ca2+ and calmodulin selectively regulate lipopolysaccharide-inducible cytokine mRNA expression in murine peritoneal macrophages.
Authors: Ohmori Y , Hamilton T A
Published: January 2023

The role of Ca2+ and Calmodulin in regulating LPS-induced cytokine gene expression in murine peritoneal macrophages has been investigated. Treatment of macrophages with three structurally distinct antagonists of Calmodulin (Trifluoperazine, N-(6-aminohexyl)-5-chloro-1-napthalenesulfonamide, and 1,3-dihydro-1-(-((4-mentyl-4H,6H-pyrrolo(1,2-a) (4,1)-benzoxazepin-4-yl)methyl)-4-peperidinyl)-2H-benzimi dazol-2-one) resulted in a characteristic modulation of the expression of three LPS-inducible cytokine genes: IL-1 alpha mRNA levels were only modestly reduced, IL-1 beta mRNA levels were markedly suppressed and IP-10 mRNA levels were increased. The same pattern of modulation was seen when LPS-stimulated cells were also treated with two different Ca2+ antagonists (8-(diethylamono)-octyl-3,4,5-trimethoxybenzoate hydrochloride and bis-(o-amonophenoxy)-ethane-N,N,N'N'-tetraacetic acid). Although the suppression of IL-1 beta mRNA accumulation by N-(6-amonohexyl)-5-chloro-1-napthalene-sulfonamide or bis-(o-amonophenoxy)ethane-N,N,N'N'-tetraacetic acid occurred even if the antagonist was added after LPS, the potentiation of IP-10 mRNA levels required the use of the agent before or along with the LPS stimulus. Elevation of intracellular Ca2+ using ionomycin did not initaite cytokine gene expression and thus changes in Ca2+ cannot replace the LPS-initiated signal. Furthermore, removal of extracellular Ca2+ did not block the response to LPS. Calmodulin antagonists selectively increased the transcriptional activity of the IP-10 gene but decreased the stability of all three mRNA measured. Thus the mechanisms involved in Ca2+/Calmodulin control of macrophage gene expression are multifactorial and contribute to the diversity of macrophage inflammatory behavior. In concert with previous reports, the present results indicate that Ca2+, acting through Calmodulin may be a necessary but insufficient component of the signalling process that mediates intracellular response to LPS. Agents that alter intracellular Ca2+ levels without inducing cytokine gene expression may thereby indirectly regulate inflammation.