bluuebunny/crossref_metadata_2025 huggingface dataset:
CD8+ T cells inhibit HIV replication in naturally infected CD4+ T cells. Evidence for a soluble inhibitor.
Authors: Brinchmann J E , Gaudernack G , Vartdal F
Published: December 2022

This study describes the inhibitory effect exerted by activated CD8+ T cells on the replication of HIV in naturally infected CD4+ T cells. Highly purified CD4+ T cells from asymptomatic HIV seropositive individuals were stimulated with anti-TCR mAb-coated beads in the presence of IL-2. HIV was subsequently reproducibly isolated in cell supernatants from all study participants (53 cultures from 42 individuals). Both autologous and allogeneic CD8+ T cells from asymptomatic HIV seropositive and healthy HIV seronegative individuals inhibited the replication of HIV in these cultures in a dose-dependent manner. CD8+ T cells from patients with AIDS showed reduced or no such inhibitory activity. The inhibitory effect was not dependent on direct cell-cell contact: an inhibitory effect was exerted by CD8+ T cells across a semipermeable membrane, and an inhibitory activity was also exerted by the cell-free supernatants from activated CD8+ T cells. These results suggest that activated CD8+ T cells secrete a soluble inhibitor of HIV replication.
VH and VL gene usage by murine IgG antibodies that bind autologous insulin.
Authors: Ewulonu U K , Nell L J , Thomas J W
Published: December 2022

To assess the recognition structures of antibodies that bind a self-Ag, we used mRNA analysis to identify the V region genes of IgG antibodies that bind autologous insulin. Four anti-insulin mAb from primary immunization of BALB/c mice use different combinations of H and L chain V region genes. Two VH genes are from the V-gam 3-2 and V-gam 3-8 families that are infrequently expressed in adult BALB/c mice, and two VH genes are members of the J558 family. Each anti-insulin antibody uses a different Vk gene family. Two antibodies express common Vk genes (Ox1 and Vk21C), whereas two other Vk genes are unusual in BALB/c mice. One Vk gene may represent a BALB/c equivalent of the VkOx2 subfamily and another is identical to a Vk used by anti-idiotypic antibodies from C57Bl/6 mice. When compared with known germ-line counterparts, all of the Vk sequences are close to germ-line configuration. In contrast, the germ-line counterparts for the anti-insulin VH genes are not known, however, they differ only in five to seven predicted amino acids from VH of other expressed antibodies. One antibody (mAb 123) differs in one amino acid in complementarity-determining regions 1 and 2 from the VH of the murine tumor BCL1, and another (mAb 126) employs an unmutated DFL16.1 germ-line D segment. These data suggest that antibodies binding autologous insulin use V gene components that are not extensively mutated, even when derived by immunization with heterologous insulin.
Molecular events in B lymphocyte differentiation. Inducible expression of the endogenous mouse mammary tumor proviral gene, Mtv-9.
Authors: King L B , Lund F E , White D A , Sharma S , Corley R B
Published: December 2022

We have previously shown that the steady state levels of transcripts encoded by an endogenous mouse mammary tumor virus (MMTV) increase during LPS-induced differentiation of both normal B lymphocytes and an inducible B cell lymphoma, CH12. A large body of evidence suggests that MMTV expression is primarily limited to mammary tissues and that expression in cell lines from nonmammary tissues is accompanied by viral amplification and alterations in the transcriptional control regions of the viral long terminal repeat. We have, therefore, carefully characterized MMTV expression in CH12 cells and in other cells of the B lineage in order to determine if the expression of MMTV transcripts in differentiating B cells results from the "abnormal" transcriptional regulation seen in other nonmammary tissue. In this manuscript, we present evidence that MMTV transcripts are expressed in a variety of cells of the B lineage and that the levels of constitutive expression vary among the different cells. On the other hand, T cell lymphomas lacking amplified MMTV do not contain proviral transcripts, suggesting that MMTV transcription may be preferentially expressed in B lymphocytes. We demonstrate that MMTV transcripts are up-regulated during cytokine-mediated as well as LPS-mediated differentiation, and that most, if not all, expression is due to the activity of a single proviral gene, Mtv-9, in CH12 cells. Furthermore, the expression of MMTV transcripts in CH12 cells neither requires nor is accompanied by amplification of the provirus. Sequence analysis demonstrates that the U3 region of the expressed Mtv-9 long terminal repeat contains neither deletions nor insertions, and the well-characterized enhancer and promoter sites in the glucocorticoid response element which are known to be involved in transcriptional regulation of MMTV in mammary tissues have not been disrupted. These data suggest that the Mtv-9 locus behaves as a normal somatic gene which is differentially regulated during B cell development and differentiation. Unlike the events which lead to MMTV expression in other nonmammary tissues, B cells may express transcription factor(s) which are capable of inducing expression of endogenous MMTV proviral genes during the natural course of differentiation. Analysis of the mechanisms which control the expression of this gene should be useful in characterizing the molecular events which govern B cell differentiation.
Mapping the fine specificity of a cytolytic T cell response to HIV-1 nef protein.
Authors: Koenig S , Fuerst T R , Wood L V , Woods R M , Suzich J A , Jones G M , de la Cruz V F , Davey R T , Venkatesan S , Moss B
Published: December 2022

Epitope mapping of a MHC class I-restricted cytotoxic T cell response to nef, a regulatory protein of HIV, was performed with fresh PBMC from HIV-seropositive donors and target cells pulsed with a panel of overlapping peptides of the nef protein. These nef-specific CTL recognized a synthetic peptide of 10 residues derived from a nonamphipathic, highly conserved region of the nef protein in association with the HLA A3.1 molecule. Using human cell transfectants expressing mutations of the A3 molecule, we demonstrated that the amino acid at position 152 of the A3.1 molecule appears to be critical for detection of this response. Thus, rapid analysis of the epitopes of HIV proteins stimulating CTL responses can be achieved using a combination of fresh donor PBMC and target cells pulsed with synthesized peptides.
T lymphocyte recognition of a celiac disease-associated cis- or trans-encoded HLA-DQ alpha/beta-heterodimer.
Authors: Lundin K E , Sollid L M , Qvigstad E , Markussen G , Gjertsen H A , Ek J , Thorsby E
Published: December 2022

The HLA-associated susceptibility to develop celiac disease may to a large extent be attributed to the combination of particular DQA1 and DQB1 genes, i.e., the DQA1*0501 and DBQB1*0201 alleles, located either in cis position (on the DR3DQw2 haplotype) or in trans position (DR5DQw7/DR7DQw2 heterozygous individuals). We report three alloreactive T lymphocyte clones that recognize an HLA-DQ alpha/beta heterodimer both when the DQA1*0501 and DQB1*0201 alleles are located in cis or in trans position. Thus, the celiac disease associated DQA1 and DQB1 genes encode a functionally expressed DQ alpha/beta heterodimer.
Local production of tumor necrosis factor and IFN-gamma in tuberculous pleuritis.
Authors: Barnes P F , Fong S J , Brennan P J , Twomey P E , Mazumder A , Modlin R L
Published: December 2022

TNF and IFN-gamma are thought to be involved in the immune response to mycobacterial infection because they exhibit antimycobacterial effects in vitro. To investigate the roles of these cytokines in vivo at the site of disease activity in human tuberculosis, we evaluated local cytokine production in patients with tuberculous pleuritis. Both TNF and IFN-gamma were selectively concentrated 5- to 30-fold in pleural fluid, compared to blood of the same patients. Messenger RNA for both cytokines was detected in pleural tissue by in situ hybridization, suggesting that selective cytokine concentration is due to local cytokine production. Two Mycobacterium tuberculosis cell wall components, the protein-peptidoglycan complex and lipoarabinomannan, caused dose-dependent release of TNF by pleural fluid mononuclear cells and may constitute the stimuli for TNF production in the pleural space. In contrast to results obtained for TNF release, the protein-peptidoglycan complex, but not lipoarabinomannan, stimulated IFN-gamma release by pleural fluid mononuclear cells. The clinical manifestations of tuberculous pleuritis, such as fever, exudative pleural effusion, and tissue necrosis, may be due to the effects of elevated local TNF concentrations, produced in response to mycobacterial cell wall components.
Differential responses of rat trophoblast cells and embryonic fibroblasts to cytokines that regulate proliferation and class I MHC antigen expression.
Authors: Hunt J S , Atherton R A , Pace J L
Published: December 2022

TNF-alpha and type I IFN (IFN-alpha/beta) are present in the uteroplacental unit during the course of normal gestation. IFN-gamma is likely to be present during infections. To identify potential effects on two types of blastocyst-derived cells, TNF-alpha, IFN-alpha/beta, and IFN-gamma were tested for the ability to modulate proliferation and the expression of class I MHC Ag by rat trophoblast cells and embryonic fibroblasts. The three cytokines had opposite influences on cellular proliferation by the two types of cells. Growth of the trophoblast cells was inhibited by TNF-alpha, IFN-alpha/beta, and IFN-gamma, whereas both TNF-alpha and IFN-alpha/beta enhanced fibroblast proliferation. The two endogenous cytokines had different effects on class I Ag expression by trophoblast cells and fibroblasts: TNF-alpha failed to induce trophoblast cell class I Ag and IFN-alpha/beta was a poor inducer whereas fibroblast Ag were induced by both cytokines. Moreover, combinations of TNF-alpha and IFN did not increase trophoblast cell class I Ag whereas the same combinations synergized to induce class I Ag expression by fibroblasts. In contrast, IFN-gamma was a highly efficient inducer on both types of cells. The results suggest that 1) cytokines in the uteroplacental unit may orchestrate some of the events associated with placental and embryonic development by exerting differential effects on two embryologically distinct types of cells and that 2) infections may disrupt normal events.
Precursors (pre-CFCmulti) of multilineage hemopoietic colony-forming cells quantitated in vitro. Uniqueness of IL-1 requirement, partial separation from pluripotential colony-forming cells, and correlation with long term reconstituting cells in vivo.
Authors: Iscove N N , Yan X Q
Published: December 2022

Pluripotential colony-forming cells (CFCmulti) from mouse marrow can expand significantly in number during 4 days of suspension culture with IL-1 and IL-3. In this study, the cells ("pre-CFCmulti") which originate this response are characterized in terms of their frequency, progeny number, factor requirements, buoyant density, and extent of restoration following marrow transplantation. Parallel measurements of both CFCmulti and cells providing long term marrow reconstitution in vivo allowed direct comparisons to be made with pre-CFCmulti. The proliferative response of pre-CFCmulti was found to depend uniquely on the combination of IL-1 and IL-3, and neither of these regulators was replaceable by any of IL-4, IL-6, IL-7, GM-CSF, G-CSF, M-CSF or LIF. After separation on density gradients, pre-CFCmulti were recovered in fractions of lower density than most of the CFCmulti, but in the same fractions that contained most of the in vivo reconstituting cells. After irradiation and marrow transplantation, marrow CFCmulti were restored to near normal levels, while both pre-CFCmulti as well as reconstituting stem cells remained profoundly depressed. These results show pre-CFCmulti to be distinct from most CFCmulti and to represent the closest approach to quantitative detection of reconstituting stem cells so far achieved in vitro.
Thymus-dependent antiidiotype and anti-antiidiotype responses to a dinitrophenyl-specific monoclonal antibody.
Authors: Baskin J G , Ryan T M , Vakil M , Kearney J F , Lamon E W
Published: December 2022

BALB/c mice were inoculated i.p. with graded doses of a DNP-specific, IgM mAb (designated 57.1). Injection with unmodified 57.1 in the absence of adjuvants resulted in the generation of an anti-Id response (Ab2) and an anti-anti-Id response (Ab3). The generation of serum anti-Id antibodies was found to be thymus dependent. Nude mice immunized with 57.1 were unable to produce a serum Ab2 response above nonimmunized controls whereas euthymic mice receiving identical doses of 57.1 produced strong Ab2 responses. To examine the specificity of serum anti-Id, sera from mice receiving 57.1 were screened against a panel of mAb representing at least five distinct VH gene families. Serum titers were significantly higher against 57.1 than against any of the other antibodies in the panel. Three of the antibodies in this panel bind FD5-1, a monoclonal anti-Id (Ab2) that also binds 57.1. However, sera from mice receiving 57.1 bound 57.1 only. Thus, the serum Ab2 response appears to be highly specific for idiotopes on 57.1. The predominant isotype of these anti-Id antibodies was IgG1. The number of isotypes detected increased in a dose dependent manner with all IgG subclasses having anti-Id specificity in sera from animals receiving the higher doses of 57.1. Further analysis of the serum demonstrated that approximately 8% of the Ab2 response was paratope-specific (inhibitable by the monovalent hapten DNP-lysine). The same sera were analyzed for the presence of Ab3 by binding to the monoclonal anti-Id antibody FD5-1. Lower serum titers of Ab3 were generated in comparison to serum titers of Ab2. Analysis of the binding specificity of the Ab3 response revealed that DNP-BSA was able to partially inhibit the binding of serum IgM and IgG Ab3 to FD5-1. A subset of the Ab3 response. Ab1' that is specific for DNP was observed in a direct binding assay where detectable amounts of DNP binding IgM, IgG1, and IgG3 isotypes were present. We have thus described a complete circuit (Ab1----Ab2----Ab3) of antibodies within the Id network by immunizing animals with an unmodified mAb in the absence of Ag or adjuvants.
Activation of the alternative pathway of complement by twelve different rabbit-mouse chimeric transfectoma IgA isotypes.
Authors: Schneiderman R D , Lint T F , Knight K L
Published: December 2022

Previous experiments have resulted in the identification and cloning of 13 nonallelic genes encoding the constant region of rabbit IgA H chains. The genes, C alpha 1 to C alpha 13, were each cloned into an expression vector containing the VDJ gene of a dansyl (DNS)-binding murine hybridoma and the constructs were then transfected into SP2/0 cells that were producing murine kappa-L chains from the DNS-binding hybridoma. Of the 13 resulting transfectomas, 12 were shown, by ELISA, to secrete DNS-binding chimeric rabbit-mouse IgA molecules. These transfectoma antibodies, representing 12 different isotypes, are of high affinity and provide a unique source of Ag-specific IgA for comparison of the functions of the multiple IgA isotypes. One such function for antibodies is activation of C by either the classical or alternative pathway. We have used the DNS-binding IgA transfectoma antibodies in C assays based on binding of rabbit C3 to IgA-Ag complexes in an ELISA. The results demonstrated that all 12 IgA isotypes are capable of activating C by the alternative pathway but that none can activate C by the classical pathway. Control experiments demonstrated that activation was hapten dependent and was not caused by endotoxin contamination. These data demonstrate that Ag-specific IgA molecules, unmodified by heat or chemical aggregation, activate C by the alternative pathway but not by the classical pathway.
Identification of effector cell protease receptor-1. A leukocyte-distributed receptor for the serine protease factor Xa.
Authors: Altieri D C , Edgington T S
Published: December 2022

Mitogenesis, cell differentiation and immune-inflammatory responses are regulated by the coordinated assembly of proteases with specific cellular receptors. We have investigated the possibility that immune effector cells may express a high-affinity protease receptor. To address this hypothesis, we have generated mAb to factor V and its activated form Va, a circulating plasma protein that binds the serine protease of the coagulation cascade, factor Xa. Further, by flow microfluorimetry screening, we have isolated a panel of these mAb that recognize a surface molecule expressed on transformed monocytic cells. We now show that these mAb bind to blood monocytes, to CD3- CD16+ CD56+ NK cells, and with considerable heterogeneity, to neutrophils. A small subset of CD3+ cells (5 to 10%) was also identified by these probes and further phenotypically characterized by two-color flow microfluorimetry as predominantly coexpressing CD2, CD4 or CD8, CD57, CD11b, and alpha/beta TCR. This subset of CD3+ cells was expanded in vitro by both lectin- or Ag-specific stimulation. In addition, long term alloreactive stimulation resulted in approximately 8- to 10-fold increased expression of the molecule recognized by these mAb. Functional analyses were performed on a selected T cell clonal derivative of the transformed cell line HuT 78. These cells bound 125I-factor Xa in a specific reaction saturated at 194,000 +/- 26,000 molecules/cell with a Kd approximately 10 to 20 nM and inhibited by the mAb panel described above. These data suggest that immune effector cells express a dynamically regulated protease receptor that is immunologically related to the plasma coagulation protein factor V and its activated form Va. We propose the term effector cell protease receptor-1 to tentatively identify this molecule, and we speculate on its possible involvement in specialized protease-mediated effector functions.
Identification of high affinity receptors for human monocyte chemoattractant protein-1 on human monocytes.
Authors: Yoshimura T , Leonard E J
Published: December 2022

The binding of human monocyte chemoattractant protein-1 (MCP-1) to human monocytes was studied. MCP-1 was radioiodinated with Iodo-beads (Pierce Chemical Co., Rockford, IL) without significant loss of biologic activity. 125I-MCP-1 binding to PBMC occurred within 5 min at 0 degrees C and the binding was inhibited by unlabeled MCP-1 dose dependently but not by neutrophil attractant/activation protein-1 or FMLP. 125I-MCP-1 bound to monocytes; no significant binding to either neutrophils or lymphocytes was observed. Scatchard plot analysis indicated that monocytes had a minimum of 1700 +/- 600 binding sites per cell with a Kd of 1.9 +/- 0.2 x 10(-9) M. For analysis of binding by flow cytometry, MCP-1 was biotinylated. In contrast to radioiodination, biotinylation resulted in loss of activity; potency was 10-fold less, but the efficacy was retained. Detection by flow cytometry of bound biotinylated MCP-1 with avidin-FITC confirmed results obtained with 125I-MCP-1. Biotinylated MCP-1 bound to monocytes but not to lymphocytes; and the binding was inhibited by a 100-fold excess of unlabeled MCP-1.
Cryptosporidium parvum merozoites share neutralization-sensitive epitopes with sporozoites.
Authors: Bjorneby J M , Riggs M W , Perryman L E
Published: December 2022

Sporozoites and merozoites are stages in the life cycle of Cryptosporidium parvum that can cyclically infect intestinal cells, causing persistent infection and severe diarrhea in immunodeficient patients. Infection by sporozoites can be neutralized by surface-reactive mAb. We show that merozoite infectivity can also be neutralized by surface-reactive mAb. To do this, viable C. parvum merozoites were isolated by differential and isopycnic. centrifugation, and distinguished from sporozoites by transmission electron microscopy. Differential reactivity with a panel of seven mAb was used to determine the amount of sporozoite contamination in isolated merozoite preparations. The isolated merozoites were distinguished from sporozoites (p less than 0.0001) by four sporozoite-specific mAb (16.332, 16.502, 17.25, and 18.357) in an indirect immunofluorescence assay. Three mAb (16.29, 17.41, and 18.44) consistently reacted with both merozoites and sporozoites. Isolated merozoites were infectious for neonatal mice when administered by intraintestinal injection. Infectivity for mice was significantly neutralized (p less than 0.05) when 1 to 2 x 10(5) merozoites were incubated with sporozoite-neutralizing mAb 17.41 or 18.44, before inoculation. Merozoites incubated with an isotype control mAb remained infectious for neonatal mice. We conclude that C. parvum merozoites share neutralization-sensitive epitopes with sporozoites.
CD14 is a member of the family of leucine-rich proteins and is encoded by a gene syntenic with multiple receptor genes.
Authors: Ferrero E , Hsieh C L , Francke U , Goyert S M
Published: December 2022

We have isolated and characterized genomic and cDNA clones encoding the murine homolog of the human monocyte/granulocyte cell surface glycoprotein, CD14. As in man, the expression of murine CD14 is limited to the myeloid lineage. The murine and human CD14 genes are highly conserved in their intron-exon organization and nucleotide sequence. Their deduced protein sequences show 66% amino acid identity. In both mouse and man, the CD14 protein contains a repeating (10 times) leucine-rich motif (LXXLXLX) that is also found in a group of heterogeneous proteins from phylogenetically distant species. The CD14 gene has been mapped to mouse chromosome 18 which also contains at least five genes encoding receptors (Pdgfr, Adrb2r, li, Grl-1, Fms). Thus CD14 and the receptor genes form a conserved syntenic group localized on mouse chromosome 18 and human chromosome 5. The inclusion of CD14 in the family of leucine-rich proteins, its expression profile and the murine chromosomal localization support the hypothesis that CD14 may function as a receptor.
Structure of the murine mb-1 gene encoding a putative sIgM-associated molecule.
Authors: Kashiwamura S , Koyama T , Matsuo T , Steinmetz M , Kimoto M , Sakaguchi N
Published: December 2022

Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3'-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5'-flanking region has sequence stretches homologous to IgVH 5'-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgVH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3'-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.
Expression of the human MHC, HLA-DQW6 genes alters the immune response in C57BL/6 mice.
Authors: Nishimura Y , Iwanaga T , Inamitsu T , Yanagawa Y , Yasunami M , Kimura A , Hirokawa K , Sasazuki T
Published: December 2022

In an attempt to obtain direct evidence for the critical role of HLA class II molecules in regulating the immune response, genomic genes for alpha- and beta-chains of HLA-DQw6 from HLA-Dw12 haplotype were introduced into the C57BL/6 (B6) strain of mouse and a line of HLA-DQw6 transgenic mouse was obtained. Tissue specificity of the expression of the transgenes was much the same as that of murine I-Ab genes. DQw6 molecules were expressed on B cells and macrophages in spleen cells and about 30 to 40% of the I-Ab+ spleen cells were positive for DQw6. The HLA-DQw6 transgenic B6 mouse became tolerant to the DQw6 molecules, as evidenced by the MLR and antibody production specific to the DQw6 molecules. The HLA-DQw6 transgenic B6 mouse showed a strong immune response to streptococcal cell wall antigen (SCW), whereas the B6 mouse was a low responder to SCW. The SCW-specific T cell line was established from the transgenic mouse and this T cell line recognized SCW in the context of HLA-DQw6 molecules expressed on the mouse L cell transfectant or on human monocytes. The proliferative response to SCW of primed lymph node T cells and the SCW-specific T cell line derived from the transgenic mice was inhibited by anti-HLA-DQ mAb. Thus, it is clear that the HLA-DQw6 genes acted as major histocompatibility genes in these transgenic mice.
The role of lipocortin I in macrophage-mediated immunosuppression in tumor-bearing mice.
Authors: Sakata T , Iwagami S , Tsuruta Y , Teraoka H , Hojo K , Suzuki S , Sato K , Suzuki R
Published: December 2022

The soluble mediators and/or mechanisms involved in immunosuppression in tumor-bearing hosts are not well characterized, although macrophages have long been recognized as major participants. We have investigated the role of lipocortin I, a phospholipid-binding protein, in macrophage-mediated immunosuppression in tumor-bearing mice. Proliferation of splenic lymphocytes in response to the mitogens (PHA, Con A, LPS, and PWM) was severely suppressed in tumor (Sqc-NH-1 carcinoma)-bearing mice. This immunosuppression was associated with a decrease in T and B lymphocytes and an increase in macrophages in these spleens. Mac-2+ macrophages were found only in spleens from tumor-bearing mice. Splenic macrophages from tumor-bearing, but not normal, mice were responsible for this immunosuppression, as revealed by negative and positive selection experiments. The levels of lipocortin I mRNA expression were markedly increased in peripheral blood cells from tumor-bearing mice as compared with those from normal mice. Lipocortin I mRNA was strongly induced in splenic mononuclear cells from tumor-bearing mice. Furthermore, these cells displayed increased expression of lipocortin I protein, as judged by Western blot analysis with polyclonal anti-lipocortin I serum. Some nonimmune organs such as the heart, submaxillary gland, muscle, and bladder also displayed increased levels of lipocortin I mRNA expression in tumor-bearing mice. Mac-2+ macrophages among the splenic mononuclear cells in tumor-bearing mice expressed lipocortin I mRNA, as judged by negative and positive selection experiments. Most of these Mac-2+ macrophages also had Mac-1 and Mac-3 Ag. Lipocortin I protein was increased in the serum of tumor-bearing mice as compared with normal mice. The culture supernatants of splenic cells from tumor-bearing mice suppressed the mitogenic responses of splenic cells from normal mice, and addition of anti-lipocortin I antiserum inhibited this suppression. Furthermore, recombinant mouse lipocortin I suppressed mitogenic responses of splenic cells from normal mice. In summary, Mac-2+ macrophage-derived lipocortin I was largely involved in immunosuppression in tumor-bearing mice.
Analysis of Th1 and Th2 cells in murine gut-associated tissues. Frequencies of CD4+ and CD8+ T cells that secrete IFN-gamma and IL-5.
Authors: Taguchi T , McGhee J R , Coffman R L , Beagley K W , Eldridge J H , Takatsu K , Kiyono H
Published: December 2022

After Ag and/or mitogen stimulation, cloned mouse Th1 and Th2 cells produce different cytokines that contribute to induction of particular B cell isotype responses. In this regard, IL-5 produced by Th2 cells has been shown to enhance IgA synthesis in LPS-triggered splenic (SP) B cell or in unstimulated Peyer's patch (PP) B cell cultures. This raises the possibility that Th2 cells may occur in higher frequency in gut-associated tissues, because B cells in these areas are committed to IgA synthesis. We have used an ELISPOT assay to detect individual T cells producing IFN-gamma or IL-5. For the IL-5 assay, the mAb TRFK-5 and biotinylated TRFK-4 were used in coating and detection, respectively, whereas the mAb R4-6A2 and biotinylated XMG 1.2 were similarly used for enumeration of IFN-gamma-specific spot forming cells (SFC). Specificity of each assay was tested by using Con A-activated, cloned Th1 (H66-61) or Th2 (CDC-25) cells, where the Th1 cells only produced IFN-gamma SFC and the Th2 cells only gave IL-5-specific spots. Further, preincubation of biotinylated TRFK-4 or XMG 1.2 with rIL-5 or IFN-gamma, respectively, abrogated the formation of specific spots when tested with Con A-activated SP CD4+ T cells. Both IFN-gamma and IL-5 were produced de novo, because treatment of T cells with cycloheximide inhibited both IFN-gamma and IL-5 SFC. We have assessed the numbers of T cells spontaneously secreting these cytokines in PP and in lamina propria and intraepithelial lymphocyte (LPL and IEL) populations. Moderate levels of IL-5 SFC occurred in the IEL subset, whereas higher levels existed in the LPL population. Although significant numbers of IFN-gamma SFC (Th1-type) were also seen in LPLs, the frequency of IL-5 SFC was always higher (Th1:Th2 in LPL = 1:3). In IELs, equal numbers of IFN-gamma and IL-5 SFC were seen. Interestingly, CD8+ IEL T cells produced these two cytokines. In contrast, T cells freshly isolated from PP, an IgA inductive site, contained smaller numbers of IL-5- or IFN-gamma-secreting cells and SP T cells had essentially no SFC. When PP or SP T cells were stimulated with Con A, significant and approximately equal numbers of IFN-gamma- and IL-5-producing cells appeared.(ABSTRACT TRUNCATED AT 250 WORDS)
IgD-receptor-positive human T lymphocytes. I. Modulation of receptor expression by oligomeric IgD and lymphokines.
Authors: Coico R F , Tamma S L , Bessler M , Wei C F , Thorbecke G J
Published: December 2022

Studies with human myeloma-derived IgD have demonstrated the existence of IgD-R on peripheral blood T cells. These receptors, which are detected by rosetting with IgD-coated ox E (IgD-rosette-forming cells), are competitively inhibited by IgD, but not by IgM or IgG. Similar results were obtained with human T cell clones and T hybridomas derived from such clones either by rosetting assays or by staining with biotinylated-IgD. In agreement with studies of murine IgD-R+ cells, human IgD-R can be up-regulated by exposure of peripheral blood T cells, T cell clones, and hybridomas derived from such clones, to oligomeric IgD, but not monomeric IgD. Human IgD-R can also be induced by IL-2, IL-4, and IFN-gamma. In contrast with studies of murine IgD-R, which are expressed primarily by CD4+ cells, phenotyping studies show that both the CD4+ and CD8+ human T cell subsets are capable of expressing IgD-R.
Serologic, biologic, and western blot analysis of a T suppressor factor with specificity for the hapten 4-hydroxy-3-nitrophenyl acetyl derived from serum-free medium.
Authors: Gallina M J , Kuchroo V K , Steele J K
Published: December 2022

A T cell hybridoma producing a T suppressor factor (TsF) with specificity for the hapten nitrophenyl was converted to long term growth in serum-free medium and its product tested by serology, bioactivity, and Western blot analysis. Results indicated that Ag-specific suppressive activity was present in serum-free medium and this TsF could exhibit the characteristics ascribed to it by various groups: it could bind nominal Ag with specificity, it was bound by anti-TsF mAb, and it could mediate Ag-specific suppression both in vivo and in vitro. Western blot and SDS-PAGE analysis of this purified TsF revealed a 43-kDa single chain protein.
Bursectomy of chicken embryos at 60 hours of incubation leads to an oligoclonal B cell compartment and restricted Ig diversity.
Authors: Mansikka A , Jalkanen S , Sandberg M , Granfors K , Lassila O , Toivanen P
Published: December 2022

Chickens that have been surgically bursectomized at 60 h of embryonic development usually generate Ig producing B cells; however, the bursectomized chickens are incapable of specific antibody responses, even after repeated immunization. In the present work, we analyzed the molecular basis of this immunodeficiency. In the bursectomized chickens, DNA sequencing revealed a repertoire of Ig L and H chains with a low number of different V-J and V-D-J joints, indicating an oligoclonal B cell compartment. In addition, the L and H chains belonging to each B cell clone had similar gene conversion events in the V region. In situ hybridization to Harderian gland tissue sections showed, that B cells of the bursectomized chickens were, however, capable of terminal plasma cell maturation. Thus, in chickens that were lacking the bursal microenvironment, 1) only a few B cell precursors differentiated into mature Ig-producing B cells, 2) low rate of gene conversion resulted in restricted Ig diversity. Regarding the chicken B cell differentiation, the present data support a model that the induction of B cell differentiation is a bursa-independent event, whereas the bursa of Fabricius has a crucial role in the amplification and diversification of the embryonic B cell repertoire.
HIV inhibits the early steps of lymphocyte activation, including initiation of inositol phospholipid metabolism.
Authors: Hofmann B , Nishanian P , Baldwin R L , Insixiengmay P , Nel A , Fahey J L
Published: December 2022

Mechanisms accounting for HIV-associated suppression of lymphocyte proliferation were investigated. In previous work we demonstrated that purified and inactivated HIV-suppressed lymphoid cell proliferation. In this report we used an inactivated preparation of HIV obtained from infected CEM cells grown in serum free media and demonstrated that this HIV-associated suppression acted in the early steps of activation to inhibit the incorporation of radiolabeled phosphorus into phosphatidylinositol 4,5-bisphosphate and phosphatidic acid. Initially we showed that both purified CD4 and CD8 T lymphocyte subsets were affected and HIV-associated inhibition did not require the CD4 molecule. Impaired lymphocyte blastogenesis (decreased size and granularity and decreased expression of receptors to IL-2 and transferrin) in response to PHA indicated an effect of inactivated HIV on the early steps of activation. This was confirmed by time studies where 1) a 2 min HIV-pretreatment followed by washing before stimulation was sufficient to inhibit PHA induced proliferation of normal lymphocytes, and 2) addition of HIV to PHA prestimulated lymphocytes failed to inhibit proliferation, e.g., there was no effect on preactivated lymphocytes. HIV was mainly inhibitory of lymphocyte proliferation induced by PHA or mAb to the CD3 receptor. In contrast to the effect on the CD3/TiR, responses via the CD2 receptor were not suppressed, e.g., stimulation with the monoclonal antibodies T11(2) + T11(3). Inasmuch as responses by direct A23187 + PMA stimulation of intracellular pathways were also inhibited, it appears that the HIV-induced defect was not (or not only) membrane receptor mediated. The earliest (min) measurable event after stimulation was the initial increase in intracellular Ca2+ which was unaffected by HIV pretreatment. The next measurable event (min to h) of stimulation is a sustained increase in inositol phospholipid turnover. Pretreatment of mononuclear cells with inactivated HIV resulted in a decreased inositol phospholipid turnover as judged from decreased 32P incorporation into phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate. This led to decreased generation of DAG as reflected in the reduced radiolabeling of its metabolite PA. Reduced availability of DAG presumably interferes with pkC activation and leads to decreased expression of receptors for IL-2 and transferrin and impaired proliferation.
Recombinant human IgG1-murine IgE chimeric Ig. Construction, expression, and binding to human Fc gamma receptors.
Authors: Shopes B , Weetall M , Holowka D , Baird B
Published: December 2022

We have constructed a set of chimeric Ig by exchanging corresponding H chain C domains between human (hu) IgG1 and murine (m) IgE. We used this set of Ig to dissect the interaction of individual Ig domains with human Fc gamma receptors. Only one of the chimeras, epsilon/C gamma 2,3 (an mIgE with C epsilon 3 and C epsilon 4 replaced by C gamma 2 and C gamma 3 from huIgG1), binds tightly to the human Fc gamma RI on U937 cells. We found that epsilon/C gamma 2,3 has only twofold lower affinity for Fc gamma RI as compared to huIgG1. The gamma/C epsilon 4 (huIgG1 with C epsilon 4 replacing C gamma 3) binds weakly to Fc gamma RI. The other chimeric Ig, epsilon/C gamma 3, epsilon/C gamma 2, and gamma/C epsilon 3, as well as mIgE do not bind detectably to Fc gamma RI. From these data we conclude that the C gamma 2 domain is crucial for binding and contains the majority of the binding site for Fc gamma RI on IgG1. The C gamma 3 domain makes a smaller contribution to the binding, and the C gamma 1 domain and the hinge region have very little effect on the Fc gamma RI-IgG1 interaction. The chimeric epsilon/C gamma 2,3 and huIgG1 both mediate the formation of rosettes between K562 cells and antigen-sensitized E with similar concentration dependences. These results suggest similar ability to bind to Fc gamma RII. The other chimeric Ig do not cause rosettes in this assay system. Hence, both C gamma 2 and C gamma 3 seem to be required for binding to Fc gamma RII, but the C gamma 1-hinge region has no detectable effect.
IgG-dependent generation of platelet-activating factor by normal and low density human eosinophils.
Authors: Cromwell O , Wardlaw A J , Champion A , Moqbel R , Osei D , Kay A B
Published: December 2022

We have compared normal and low density human eosinophils for their ability to generate platelet activating factor (PAF) in response to IgG-dependent and nonimmunologic stimulation. After 45 min incubation with IgG-coated Sepharose beads the concentrations of cell-associated PAF recovered from normal density eosinophils were significantly greater than from low-density eosinophils or neutrophils. Moreover, eosinophils stimulated with calcium ionophore A23187 had a considerably greater capacity to generate PAF than had previously been described. Although the quantities of cell-associated PAF recovered from normal and low density eosinophils and neutrophils after A23187 stimulation were similar, the amounts of extracellular PAF recovered from both eosinophil populations were significantly greater than from neutrophils. The amounts of PAF recovered from the low density eosinophils may not reflect the full synthetic capacity of these cells, because PAF-turnover was found to be more rapid than that observed with normal density eosinophils. When exogenous [3H]PAF was added to the two stimulated eosinophil populations subsequent analysis of the [3H]PAF metabolites by DIOL-HPLC revealed that low density eosinophils incorporated PAF into the phosphatidylcholine (PC) pool more rapidly than did normal density eosinophils or neutrophils. Alkaline hydrolysis of the PC fraction from whole cell extracts followed by treatment with acetic anhydride resulted in all the PC-associated radioactivity being converted to [3H]PAF, confirming PAF incorporation to PC via this pathway. These findings suggest that the contribution of eosinophils to inflammatory processes through the generation of PAF may be greater than previously appreciated, and that Ig-mediated stimulation may be important in initiating generation of the mediator. Low density eosinophils, that are presumed to be similar to tissue eosinophils, may have a role in regulating PAF concentrations in tissues through their enhanced rate of metabolism.
IgE receptor-mediated phosphatidylinositol hydrolysis and exocytosis from rat basophilic leukemia cells are independent of extracellular Ca2+ in a hypotonic buffer containing a high concentration of K+.
Authors: Hohman R J , Hultsch T , Talbot E
Published: December 2022

In isotonic buffer, IgE receptor-mediated exocytosis from rat basophilic leukemia cells is dependent on extracellular Ca2+, with half-maximal degranulation requiring 0.4 mM Ca2+. No significant exocytosis occurs in the absence of extracellular Ca2+. This absolute requirement for Ca2+ is eliminated by suspending the cells in a hypotonic buffer containing 60 to 80 mM K+; Na+ cannot substitute for K+. Optimal Ca2(+)-independent exocytosis occurs in a buffer containing 20 mM dipotassium Pipes, pH 7.1, 40 mM KCl, 5 mM glucose, 7 mM Mg acetate, 0.1% BSA, and 1 mM EGTA. The cells maintain this Ca2(+)-independent exocytosis even if they are preincubated with 1 mM EGTA for 40 min at 37 degrees C before triggering. Exocytosis is eliminated as isotonicity is approached by adding sucrose, NaCl, KCl, or potassium glutamate to the buffer. Quin 2 fluorescence measurements reveal only a very small rise in [Ca2+]i when the cells are triggered in hypotonic buffer in the absence of extracellular Ca2+ and the presence of 1 mM EGTA. In isotonic buffer, degranulation does not occur under conditions that lead to such a small rise in [Ca2+]i. Sustained IgE receptor-mediated phosphatidylinositol hydrolysis, which is also Ca2+ dependent in isotonic buffer, becomes independent of Ca2+ in the hypotonic buffer. In fact, the rate of phosphatidylinositol hydrolysis in hypotonic buffer in the absence of Ca2+ (and presence of 1 mM EGTA) is twice that observed in isotonic buffer in the presence of 1 mM Ca2+. These data show that in hypotonic buffer, the requirement of IgE receptor-mediated PI hydrolysis for extracellular Ca2+ is eliminated, and degranulation proceeds with a [Ca2+]i of 0.1 microM, the baseline level of [Ca2+]i found in resting cells. These results are consistent with the hypothesis that, in isotonic buffer, the Ca2+ requirement for mast cell degranulation is for the generation of second messengers via hydrolysis of membrane phosphatidylinositols.
B cell responses to paramyosin. Isotypic analysis and epitope mapping of filarial paramyosin in patients with onchocerciasis.
Authors: Steel C , Limberger R J , McReynolds L A , Ottesen E A , Nutman T B
Published: December 2022

To examine the fine specificity of the human immune response to filarial paramyosin, the antigenicity of an expressed rcDNA (2.55 kb) of Dirofilaria immitis paramyosin was detailed by ELISA. Using sera from patients infected with Onchocerca volvulus, we analyzed both the entire paramyosin molecule and six subcloned fragments for their IgG, IgG subclasses, and IgE responses. Patients from both Guatemala (64% positive) and Ghana (100% positive) reacted to paramyosin with specific IgG levels above normal controls. Although there was no anti-paramyosin subclass restriction common to all patients, the IgG3 response in the Ghananians was significantly greater than that of Guatemalans (p less than 0.001). IgE anti-paramyosin responses showed positive correlations with IgG2 (p less than 0.001), IgG4 (p less than 0.002), and IgG1 (p less than 0.04) responses. Epitope mapping using the IgG response to the six subclones demonstrated preferential recognition of the amino terminal end of the molecule (nucleotides 1 to 360). IgG2 reactivity was clearly localized to the most amino-terminal 120 amino acids, and the IgG4 antibodies recognized amino acids immediately adjacent to this fragment. These studies examining the fine specificity of anti-filarial immune reactions should provide a method for understanding how parasites either evade or induce host immune responses.
Cognate interactions between helper T cells and B cells. IV. Requirements for the expression of effector phase activity by helper T cells.
Authors: Bartlett W C , McCann J , Shepherd D M , Roy M , Noelle R J
Published: December 2022

After activation with anti-CD3, activated Th (THCD3), but not resting Th, fixed with paraformaldehyde induce B cell RNA synthesis when co-cultured with resting B cells. This activity is expressed by Th of both Th1 and Th2 subtypes, as well as a third Th clone that is not classified into either subtype. It is proposed that anti-CD3 activation of Th results in the expression of Th membrane proteins that trigger B cell cycle entry. Kinetic studies reveal that 4 to 8 h of activation with anti-CD3 is sufficient for ThCD3 to express B cell-activating function. However, activation of Th with anti-CD3 for extended periods of time results in reduced Th effector activity. Inhibition of Th RNA synthesis during the anti-CD3 activation period ablates the ability of ThCD3 to induce B cell cycle entry. This indicates that de novo synthesis of proteins is required for ThCD3 to express effector function. The ability of fixed ThCD3 to induce entry of B cell into cycle is not due to an increase in expression of CD3, CD4, LFA-1, ICAM-1, class I MHC or Thy-1. Other forms of Th activation (PMA and A23187, Con A) also induced Th effector function. Furthermore, purified plasma membranes from anti-CD3 activated, but not resting Th, induced resting B cells to enter cycle. The addition of IL-4, but not IL-2, IL-5, or IFN-gamma amplified the DNA synthetic response of B cells stimulated with PM from activated Th. Taken together these data indicate that de novo expression of Th surface proteins on activated Th is required for Th to induce B cell cycle entry into G1 and the addition of IL-4 is required for the heightened progression into S phase.
Evidence by peptide mapping that the region CD4(81-92) is involved in gp120/CD4 interaction leading to HIV infection and HIV-induced syncytium formation.
Authors: Kalyanaraman V S , Rausch D M , Osborne J , Padgett M , Hwang K M , Lifson J D , Eiden L E
Published: December 2022

Peptide fragments of the CD4 molecule were compared in their ability to 1) inhibit CD4-dependent HIV-induced cell fusion; 2) inhibit CD4-dependent HIV infection in vitro; and 3) block gp120 envelope glycoprotein binding to CD4. Peptides from the region CD4(81-92), although inactive when underivatized, were equipotent inhibitors of CD4-dependent virus infection, cell fusion, and CD4/gp120 binding when derivatized via benzylation and acetylation. Peptides of identical chemical composition, but altered sequence and derivatization pattern that blocked gp120 binding to either CD4-positive cells or solubilized CD4, also blocked infection and fusion with similar potencies. Those that did not block gp120/CD4 interaction were also inactive in HIV-1 infection and cell fusion assays. No other peptide fragments of the CD4 molecule inhibited fusion, infection, or CD4/gp120 interaction. The peptide CD4(23-56), derived from a region of CD4 implicated in binding of CD4 antibodies that neutralize HIV infection and cell fusion, had no effect on CD4-dependent cell fusion, HIV-1 infection, or CD4/gp120 binding, but did reverse OKT4A and anti-Leu 3a blockade of gp120 binding to CD4. These data provide evidence that the 81-92 region of CD4 is directly involved in gp120 binding leading to CD4-dependent HIV infection and syncytium formation. Previous observations with structural mutants of CD4 suggest that the CDR2-homologous region of CD4 is also involved, either directly or indirectly, in binding of gp120 to CD4. The CDR2- and CDR3-like domains of CD4 may both contribute to the binding of the HIV envelope necessary for HIV-1 infection and HIV-1-induced cell fusion.