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PubMed1992

Reduced susceptibility to HIV-1 infection of ethyl-methanesulfonate-treated CEM subclones correlates with a blockade in their protein kinase C signaling pathway.

We have described the isolation of chemically induced CEM subclones that express CD4 receptors and bind soluble gp120, yet show a markedly reduced susceptibility to infection with HIV-1. Two subclones were found to have an abnormal response to the protein kinase C (PKC) activator PMA. PMA treatment induced CD3 and CD25 (IL-2R) receptors on the parental line and on other ethyl-methanesulfonate-derived subclones, but not on these two mutants. Direct assays of PKC activity were conducted. Total cellular PKC enzymatic activity was found to be normal in these subclones. PMA-induced CD4 down-modulation occurred normally. In addition, activation of c-raf kinase was normal. Since HIV-1 long terminal repeat contains two functional nuclear factor kB (NF-kB) regulatory elements, we studied the ability of PMA to induce NF-kB binding activity by different assays. Chloramphenicol acetyl transferase (CAT) assays using the HIV-1 (-139)long terminal repeat-CAT construct showed no PMA induction of CAT activity in these subclones (unlike the parental line and other subclones). Okadaic acid, an inhibitor of phosphatases 1 and 2A, did not overcome the defect in these subclones. Gel retardation assays, using a 32P-probe containing the HIV-1 NF-kB probe and nuclear extracts from PMA-treated cells, showed significantly reduced induction of nuclear NF-kB binding proteins in these two subclones compared with wild type CEM and a control subclone. Deoxycholate treatment of cytoplasmic extracts from these subclones released much reduced NF-kB binding proteins from their cytoplasmic pools. Thus, reduced levels of PKC-induced nuclear NF-kB activity in two T cell subclones did not affect their normal cell growth, but correlated with a pronounced reduction in their susceptibility to HIV-1 infection.

Base Sequence↗
PubMed1992

CD45 alternative exon expression in murine and human CD4+ T cell subsets.

Leukocytes express a family of high m.w. glycoproteins called leukocyte common Ag (CD45), which are involved in phosphotyrosine signal transduction. Antibodies to different CD45 isoforms distinguish functionally different CD4+ T cell subsets in humans, rats, and mice. Selected protein isoforms are expressed through a process of exon splicing that is cell-type and differentiation-state specific. Splicing of the three variable exons, A, B, and C, which encode amino acids located near the extracellular amino terminus of the protein, potentially results in generation of eight different mRNA transcripts. The purpose of the present study was to determine the relative levels of all eight different CD45 transcripts present in a panel of murine CD4+ T cell lines and normal murine and human CD4+ T cell subsets separated with antibodies to CD45 variable exons. We show, as expected, that the broad features of CD45 surface isoform expression in these cells can be accounted for by the relative amounts of the eight differentially spliced transcripts. Unexpectedly, all the differences in CD45 isoform expression among the CD4+ T cell subpopulations that we measured could be accounted for by differences in the overall level of variable exon expression. We did not see differences among T cell populations in the relative expression of particular variable exons. Exon B was always found in greater abundance than exons C or A. Of the dual exon species, only AB and BC were found in CD4+ T cells. The AC species was undetectable. Human CD4+ T cells, especially those in the naive subset, express higher levels of CD45 variable exons than murine CD4+ T cells.

Animals↗
PubMed1992

Role of CD4+ (helper) T cells in the pathogenesis of murine cytomegalovirus myocarditis.

Murine cytomegalovirus causes diffuse myocardial lesions in immunologically intact young adult male BALB/cBy mice. The cardiac changes develop in and around the small penetrating blood vessels of the heart where perivascular and interstitial infiltrates of macrophages and lymphocytes accumulate. Focal lesions of the coronary vessels and the endocardium also appear. When infected mice are depleted of CD4+ T lymphocytes, myocardial lesions fail to develop even though virus replication in the heart is enhanced. Contrary wise, when CD4+ cells are adoptively transferred into infected, thymectomized, irradiated, bone marrow-repleted mice, focal perivascular necrotizing lesions of the heart develop. Depletion of CD8+ T lymphocytes fails to influence virus replication and the development of cardiac lesions. Endothelial and endocardial cells appear to be major sites of virus replication in the heart. Delayed hypersensitivity is hypothesized to be the mechanism of cardiac injury in this model system.

Animals↗
PubMedDate not supplied

[Epidemiological surveillance of infection by the human immunodeficiency virus (HIV) and of the acquired immunodeficiency syndrome (AIDS) in French Polynesia in 1991].

The authors make out a statement about HIV infection in French Polynesia at the date of 1991 December 31. 96 cases all together of seropositive and AIDS infected people were recorded. These patients are young generally (78 p.c. between 21 and 40 years old) sexually contaminated (72 out of 96) and live in Tahiti island (94 p.c.). Sex-ratio is 2.8 male/1 female. Among them, we noted 55 p.c. of Europeans, 38 p.c. of Polynesians and 7 p.c. of Asiatic people. Epidemiological monitoring of the infection was made easy because of a set of laws and possibilities of detection highly favourable. Progress of the infection is constant, with 20 new cases detected each year with a prevalence of 150 cases of AIDS per 1 million of inhabitants, French Polynesia could be classified as the 5th or 6th region of France as far as the importance of the disease. Clinical, biological and epidemiological taking of charge of patients is detailed as well as the prevention campaign.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Heart allografts in murine systems. The differential activation of Th2-like effector cells in peripheral tolerance.

Activated CD4+ Th2 cells release cytokines (IL-4,-10) that block activation & cytokine (IL-2/IFN-gamma) release by proinflammatory T (CD4+,CD8+) effector cells. To test the hypothesis that peripheral tolerance to alloantigen is linked to differential activation of CD4+ Th2 cells we measured cytokine transcripts in heart grafts (C57BL/10----C3H/HeJ) and spleens of mice rendered "tolerant" by donor-specific blood transfusion, anti-CD4 mAb pretreatment, and cyclosporine administration. The expression of IL-2/IFN-gamma transcripts was reduced greater than 90% in grafts from tolerant recipients. IL-4/IL-10 transcripts were generally enhanced and persisted in graft and recipient spleen. Accordingly adoptive transfer studies were performed to determine whether Th2-like effectors, which express Fc receptors (FcR), mediate suppression in this model. Unfractionated mononuclear cells (MC) (5 x 10(6), isolated from spleens of heart graft recipients made tolerant by DST, prolonged the survival of test grafts greater than 90 days in irradiated (680 rads) recipients reconstituted with a sufficient number of MC from spleens of naive C3H to precipitate rejection of the test graft in 18.2 days (MST, n = 5). Conversely adoptive transfer of inocula depleted of FcR+ cells on immune complex columns or with anti-FcR mAb 24G2 caused test grafts to be rejected in 8-11 days. These results suggest that peripheral tolerance to alloantigen may be linked to differential activation of Th2 cells that induce anergy by suppression. The possibility that Th2-like effectors mediate peripheral tolerance to self is discussed.

Animals↗
PubMed1992

Herpetic stromal keratitis: an immunopathologic disease mediated by CD4+ T lymphocytes.

To investigate the role of T cell subsets in the development of herpetic stromal keratitis (HSK) in a well defined model, we used an adoptive transfer approach in which thymectomized and T cell-depleted mice [T(-)] were reconstituted with different numbers of syngeneic immune T lymphocytes after topical corneal challenge with RE strain of herpes simplex virus-1. In vitro stimulated or unstimulated immune T cells obtained from cervical and retropharyngeal lymph nodes of mice with HSK were used in adoptive transfer experiments. Although T(-) mice developed an initial epithelial inflammation, stromal keratitis did not occur. Reconstitution experiments revealed that mice that received 2 x 10(7) or more unfractionated immune T cells could develop HSK lesions with severity comparable to immuno-competent control mice. In mice receiving CD8(+)-depleted populations, even fewer cells (5 x 10(6)/mouse) were able to induce significant HSK. In contrast, mice that received similar or increased numbers of cells depleted of CD4+ T lymphocytes did not develop HSK. Immune T lymphocytes transferred to mice that were mock infected on the cornea did not develop HSK, indicating that the immunopathogenic cells were virus specific and not merely reacting to autoantigens. Histopathologic examination of the diseased corneas demonstrated that the stromal inflammation in euthymic normal and T(-)-reconstituted mice was characterized by extensive polymorphonuclear leukocyte infiltration. Scattered lymphocytes, and occasional macrophages also were observed. These results provide further evidence that HSK represents an immunopathologic process mediated mainly by CD4+ T cells.

Animals↗
PubMed1992

Re-examination of peripheral blood T cell subsets in dysthyroid orbitopathy.

Patients with dysthyroid orbitopathy (DO) were grouped according to a multifactorial assessment of disease severity and the rate of disease progression. Using this system and flow cytometric measurements of T cell subsets in the peripheral blood, a significant increase in the percentage of CD4+ lymphocytes correlated with disease severity in DO patients with progressive disease. These observations are consistent with the hypothesis that the CD4+ peripheral blood T helper cells play a significant role in the progression of DO.

Adult↗
PubMed1992

Simultaneous depletion of CD4+ and CD8+ T lymphocytes is required to reactivate chronic infection with Toxoplasma gondii.

C57BL/6 mice chronically infected with an avirulent strain (ME-49) of Toxoplasma gondii were used to study the mechanisms by which T lymphocytes and IFN-gamma prevent reactivation of latent infection. Infected animals were treated with mAb, either anti-CD8, anti-CD4, anti-CD4 plus anti-CD8, anti-IFN-gamma, or anti-CD4 plus anti-IFN-gamma and the mice followed for survival, histopathology, cyst numbers, and spleen cell cytokine responses. In agreement with previously published findings, treatment with anti-IFN-gamma antibodies fully reactivated the asymptomatic infection, inducing massive necrotic areas in the brain with the appearance of free tachyzoites and death of all animals within 2 wk. Mice treated with the combination of anti-CD4 plus anti-CD8 antibodies showed augmented pathology and mortality nearly identical to the anti-IFN-gamma- treated animals. In contrast, treatment with anti-CD4 or anti-CD8 mAb alone failed to result in significantly enhanced brain pathology or mortality. In additional experiments, full reactivation of infection was observed in mice treated with anti-CD4 plus anti-IFN-gamma indicating that CD4+ lymphocytes are not required for the pathology resulting from IFN-gamma neutralization. Cytokine measurements on parasite Ag-stimulated spleen cells from mAb-treated mice indicated that both CD4+ and CD8+ cells produce IFN-gamma whereas only CD4+ cells contribute to parasite Ag-induced IL-2 synthesis. Together, these results suggest that CD4+ and CD8+ lymphocytes act additively or synergistically to prevent reactivation of chronic T. gondii infection probably through the production of IFN-gamma.

Animals↗
PubMed1992

Induction and suppression of delayed-type hypersensitivity to non-MHC antigens during lethal graft-versus-host reaction.

A delayed-type hypersensitivity reaction (DTH) to non-MHC Ag was detected during a lethal graft-vs-host reaction (GVH) induced by incompatibility for non-MHC Ag alone. In this model, when appropriate doses of B10.D2 bone marrow and lymphoid cells are grafted to irradiated (DBA/2 x B10.D2)F1 recipients, the ensuing GVH, directed against those DBA/2 non-MHC Ag absent from the B10.D2 background, results in virtually 100% mortality in less than 3 mo; donor alloimmunization against the host histocompatibility Ag considerably reduces mortality, and survival rates of 80 to 100% are common. The experiments reported here show that: 1) the cell responsible for DTH induction expresses the CD4+ CD8- phenotype; 2) CD4+ cells likewise seem to play a predominant role in the pathology of lethal GVH in this genetic combination; 3) the alloimmunization protocol that abrogates mortality also abolishes GVH-associated DTH; and 4) this suppressive effect, as shown elsewhere for the protection against mortality, is mediated by CD4- CD8- "double negative" Thy-1+ CD3+ T suppressor cells. Thus, there is a good parallel between lethal GVH and its associated DTH as concerns both induction and suppression of the two phenomena, suggesting that mortality and DTH may represent different manifestations of a common underlying mechanism. Initiation of the effector phase of DTH in the adoptive transfer model seems to be dependent on the presence of a Thy-1+ double-negative cell in the transfer inoculum; the possible relationship of this double-negative cell to the Th-1-type CD4+ DTH-mediating cell recently shown to induce lethal GVH is discussed.

Animals↗
PubMed1992

Murine AIDS superantigen reactivity of the T cells bearing V beta 5 T cell antigen receptor.

A B cell line, B6-1710, that expresses the defective virus known to induce murine AIDS stimulates a large fraction of nonprimed splenic T cells. Analysis of the T cell population responding to the B6-1710 for TCR V beta-chain usage revealed that, in addition to the previously reported V beta 5-chain-positive T cells, T cells bearing V beta 11 and V beta 12 are also specifically enriched. We have established V beta 5+ T cell lines, clones, and hybridomas expressing identical TCR with different CD4/CD8 phenotypes and demonstrated that T cell reactivity to B6-1710 is, although not absolute, dependent on the presence of CD4 molecules. Further analysis of T cell hybridomas with known J beta-chain usage revealed that D beta- and J beta-chain usage do not play crucial roles in T cell reactivity to B6-1710 B cells. However, T cell hybridomas derived from TCR-V beta gene transgenic mice were found to be heterogeneous for their reactivity to B6-1710, suggesting that the V alpha-chains associating with the transgenic V beta-chain determine T cell responsiveness to B6-1710. These data clearly demonstrate that T cell reactivity to a murine AIDS virus expressing B cell line resembles that previously reported for Mls-like superantigens.

Animals↗
PubMedDate not supplied

Characterization of human heart-infiltrating cells after transplantation. VI. Differences in the cytokines produced by individual CD4+ cloned T-cell lines with apparently identical antiidiotype-like reactivity.

Studies of cultures and cloned T-cell lines from mononuclear cell infiltrates in cardiac biopsy specimens have provided a unique resource to study the cellular basis of human organ allograft rejection. Our laboratory has previously shown that biopsy specimens placed on autologous donor MHC-class-II-specific cloned T-cell lines from previous cardiac biopsies led to the isolation of cloned T-cell lines, which appeared to be functionally "antiidiotypic" in nature. Detailed functional analysis of such CD4+ individual antiidiotype-reactive cloned T-cell lines revealed that although some augmented the proliferative response of autologous idiotype-bearing cloned T-cell lines against donor stimulator cells, others markedly suppressed the proliferative response; thus, although each of these antiidiotype-like reactive cloned T-cell lines appears to specifically react with the same idiotype-bearing donor MHC-class-II-specific cloned T-cell line, they were functionally heterogeneous. Analysis of cytokines secreted by these individual clones showed that the antiidiotype-reactive cloned T-cell lines that suppressed the response of idiotype-bearing cells appear to secrete predominantly interferon gamma, whereas those antiidiotype-reactive cloned T-cell lines that augmented the response do not secrete interferon gamma but secrete interleukin-2, -4, and -6. These preliminary data suggest that differences in the predominant cytokines secreted by these individual antiidiotype-reactive cloned T-cell lines may account for their functional differences.

Antibodies, Anti-Idiotypic↗
PubMed1992

Alveolar macrophage populations are distorted in immunocompromised patients with pneumonitis.

Alveolar macrophages (AM) were obtained by bronchoalveolar lavage (BAL) from patients presenting with pneumonitis: 30 human immunodeficiency virus (HIV)-infected individuals and 12 transplant recipients. Nine normal volunteers acted as controls. The cells were washed and cytospins prepared. Monoclonal antibodies (MoAbs) and immunoperoxidase methods were used to analyse the expression of HLA-DR molecules as well as phenotypic macrophage markers. P values apply to the differences between medians using the Mann-Whitney test. Median percentages of macrophages, lymphocytes and neutrophils were similar in all three groups. No differences were found in the median percentages of macrophages expressing the monocyte phenotype (MoAb UCHM1, CD14). However, in HIV-infected patients and transplant recipients a median of only 45% of macrophages expressed the pan-macrophage phenotype identified by MoAb EBM11 (CD68) in contrast with 98% in the normal volunteers. The AM population expressing the dendritic cell marker (MoAb RFD1) was also markedly reduced in both groups of immunocompromised patients (2 vs 28% in normal volunteers). Transplant recipients had significantly more phagocytic cells identified by MoAb RFD7 than the HIV-infected patients (25 vs 2%), but the numbers were still low when compared with the volunteers (48%). HLA-DR expression on BAL cells was reduced by 90% in both immunocompromised groups. For the transplant recipients, severity of pneumonitis was correlated with expression of dendritic cell marker RFD1, (Spearman's rank correlation r = 0.538, p less than 0.05) and pan-macrophage marker EBM11 (r = 0.581, p less than 0.05), while no such correlation was found in HIV-infected patients. These results suggest that a defective macrophage population is probably a serious factor contributing to immunosuppression.

Adult↗
PubMed1992

The diversity of the CD4+ T cell response in influenza.

We have analyzed the specificity and structural basis of the CD4+ helper T cell (Th) response of BALB/c mice to influenza virus. We find that many of the viral proteins are recognized by Th, and for one of these proteins we have defined eight distinct Th determinants. Moreover, Th that recognize a single determinant use structurally diverse T cell receptors, and display many unique specificities for the same determinant. These findings demonstrated extensive diversity at several levels of the Th response to influenza virus.

Amino Acid Sequence↗
PubMed1992

Lethal graft-versus-host disease in mice directed to multiple minor histocompatibility antigens: features of CD8+ and CD4+ T cell responses.

Lethal graft-versus-host disease (GVHD) can be induced in MHC-matched strain combinations which differ in their expression of multiple minor histocompatibility (H) antigens. It has been shown that CD8+ T cells play an important role in the development of disease directed to the minor H antigens, and that initial indications were that highly purified preparations of these cells were capable of mediating GVHD, without apparent 'help' from mature donor-derived CD4+ T cells. To further strengthen this hypothesis, the current study was undertaken with the B10.BR----CBA strain combination in which irradiated recipient mice were additionally treated with an anti-CD4 monoclonal antibody, as a single or repeated injection, to minimize the presence of either residual host CD4+ cells or recently generated donor-derived CD4+ cells at later stages of disease development. The results indicate that these treatments do not affect the GVHD outcome and that the CD8+ cells are indeed capable of inducing disease independent of CD4+ 'help'. The addition of donor CD4+ T cells in the inoculum, however, does enhance the potential of these CD8+ cells, and is observed with both low and high dosages of CD4+ cells. CD4+ T cells, on their own, have also been observed to cause GVHD directed to minor H antigens in certain strain combinations, and their response has been further characterized in this study. Results indicate that CD4+ cells capable of mediating GVHD in the B10.D2----DBA/2 strain combination can do so over a wide range of recipient irradiation exposures. The transfer of high dosages of CD4+ cells only shortens survival times of the recipients and does not afford any apparent protection phenomenon as previously observed in CD4+ cell mediated anti-class II MHC GVHD. The study also indicates that neither CD4+ nor CD8+ cells responsible for GVHD directed to minor H antigens seem capable of targeting host stem cell elements.

Animals↗
PubMed1992

[Differentiation of fetal lymphocytes with the DP-(dipeptidylpeptidase-) IV technique].

The knowledge about the ontogenicity of the human immune system based on animal experiments. In this study expulsed fetus of women with sponeous and arteficial abortions were analysed because of the content of T4(+)-lymphocytes in the lymphatic tissues. The thymus, spleen, and a piece of the bone marrow were dissected, homogenised and the lymphocytes were separated. The identification of the T4+ cells was performed by the cytochemical staining of dideptidyl peptidase IV (DP IV). It could established that from the 15th to the 26th week of gestation the number of T4+ cells increased in the thymus and spleen but not in the bone marrow. In cases with rubella infection was the number of T4+ cells in the spleen increased if the fetus have had no signs of embryopathy.

Adolescent↗
PubMed1992

Herpes simplex virus-1-specific human cytotoxic T lymphocytes are induced in vitro by autologous virus-infected mononuclear cells.

A new technique for in vitro activation of cytotoxic T lymphocytes (CTLs) specific for herpes simplex virus type 1 (HSV-1) is described. Autologous phytohemagglutinin (PHA)-activated, HSV-1-infected peripheral blood mononuclear cells (PBMC) were used, after fixation with 1% paraformaldehyde, to activate virus-specific CTLs in short-term cultures. The same unfixed PBMC were used as target cells in the cytotoxicity assay. By using this technique high levels of HSV-1-specific cytotoxic activity (50.06 +/- 16.76% at 30:1 effector:target ratio) were repeatedly obtained in 24 experiments using PBMC from 16 HSV-1 antibody-positive healthy donors, while no cytotoxic activity was observed using PBMC from 3 HSV-1 antibody-negative donors. HSV-1-induced CTLs were shown to be virus-specific as they did not lyse autologous, PHA-activated PBMC infected with influenza A virus or autologous Epstein-Barr virus (EBV) lymphoblastoid cell line (LCL), while they were able to lyse both HSV-1-infected, autologous PHA-activated PBMC and EBV-LCL. HSV-1-specific cytotoxicity was mediated by T lymphocytes, since depletion of CD3-positive cells from the effector population completely removed the killing of HSV-1-infected target cells. CD8-positive CTLs were primarily involved in the killing of HSV-1-infected targets since depletion of CD8-positive cells caused a strong reduction of virus-specific cytotoxic activity while elimination of CD4-positive lymphocytes increased killing capacity. Finally, this technique has proven to be highly reproducible, easy to perform, and thus suitable for clinical investigations.

Cell Line↗