Single-nucleotide polymorphism-defined class I and class III major histocompatibility complex genetic subregions contribute to natural long-term nonprogression in HIV infection.

We performed a genome-wide association study comparing a cohort of 144 human immunodeficiency virus (HIV type 1-infected, untreated white long-term nonprogressors (LTNPs) with a cohort of 605 HIV-1-infected white seroconverters. Forty-seven single-nucleotide polymorphisms (SNPs), located from class I to class III major histocompatibility complex (MHC) subregions, show statistical association (false discovery rate, <0.05) with the LTNP condition, among which 5 reached genome-wide significance after Bonferonni correction. The MHC LTNP-associated SNPs are ordered in ≥4 linkage disequilibrium blocks; interestingly, an MHC class III linkage disequilibrium block (defined by the rs9368699 SNP) seems specific to the LTNP phenotype.

Perturbation of CD4+ and CD8+ T-cell repertoires during progression to AIDS and regulation of the CD4+ repertoire during antiviral therapy.

The T-cell antigen receptor (TCR) repertoire was studied longitudinally by analyzing the varying lengths of the beta chain CDR3 hypervariable region during the course of HIV-1 infection and following combination antiretroviral therapy. Drastic restrictions in CD8+ T-cell repertoire usage were found at all stages of natural progression and persisted during the first six months of treatment. In contrast, significant CD4+ T-cell repertoire perturbations were not found in early stages of infection but correlated with progression to AIDS. Out of ten patients presenting with pretreatment perturbations, normalization of the CD4+ repertoire was observed in eight good responders, but not in two cases of unsuccessful therapy. These results indicate that, besides CD4+ cell count rise, an efficient control of HIV replication may allow qualitative modifications of the CD4+ repertoire balance.

Defective humoral responses and extensive intravascular apoptosis are associated with fatal outcome in Ebola virus-infected patients.

Ebola virus is very pathogenic in humans. It induces an acute hemorrhagic fever that leads to death in about 70% of patients. We compared the immune responses of patients who died from Ebola virus disease with those who survived during two large outbreaks in 1996 in Gabon. In survivors, early and increasing levels of IgG, directed mainly against the nucleoprotein and the 40-kDa viral protein, were followed by clearance of circulating viral antigen and activation of cytotoxic T cells, which was indicated by the upregulation of FasL, perforin, CD28 and gamma interferon mRNA in peripheral blood mononuclear cells. In contrast, fatal infection was characterized by impaired humoral responses, with absent specific IgG and barely detectable IgM. Early activation of T cells, indicated by mRNA patterns in peripheral blood mononuclear cells and considerable release of gamma interferon in plasma, was followed in the days preceding death by the disappearance of T cell-related mRNA (including CD3 and CD8). DNA fragmentation in blood leukocytes and release of 41/7 nuclear matrix protein in plasma indicated that massive intravascular apoptosis proceeded relentlessly during the last 5 days of life. Thus, events very early in Ebola virus infection determine the control of viral replication and recovery or catastrophic illness and death.

Tyrosine phosphorylation and association with phospholipase C gamma-1 of the GAP-associated 62-kD protein after CD2 stimulation of Jurkat T cell.

Numerous substrates are tyrosine phosphorylated upon CD2 stimulation of human Jurkat T cells using a mitogenic pair of CD2 monoclonal antibodies, including the phospholipase C (PLC)gamma-1-p35/36 complex. Most of these substrates are identically tyrosine phosphorylated after CD3 ligation, suggesting that both stimuli share the same biochemical pathway. We show, however, in this report that a 63-kD protein is specifically phosphorylated on tyrosine residues after ligation of the CD2 molecule. The tyrosine phosphorylation of p63 can be induced independently of other substrates when using a single CD2 mAb recognizing the D66 epitope of the molecule. Importantly, this CD2-induced tyrosine phosphorylation of p63 can also occur in the absence of the CD3 zeta chain membrane expression, and is also distinct from the protein tyrosine kinases p56lck and p59fyn. We demonstrate, moreover, that p63 is physically linked with PLC gamma-1 and p35/36 upon CD2 stimulation. Finally, we also show that a 62-kD protein coimmunoprecipitating with the p21ras GTPase activating protein (GAP) is heavily tyrosine phosphorylated only after CD2 stimulation. This ultimately suggests that p63 may represent in fact the 62-kD protein that associates with GAP after tyrosine phosphorylation. Taken together, these results demonstrate the occurrence in Jurkat cells of a tyrosine kinase pathway specifically coupled to the CD2 molecule. They also suggest a function of the p62-GAP-associated protein as a link between PLC gamma-1 and p21ras activation pathways after CD2 activation.

Genetic control of specific immune suppression. III. Mapping of H-2 complex complementing genes controlling immune suppression by the random copolymer L-glutamic acid50-L-tyrosine50 (GT).

Earlier studies from our laboratory demonstrated that the terpolymer of L-glutamic acid, L-alanine, and L-tyrpsine (GAT) stimulated the development of T cells capable of specifically suppressing the antibody responses in vivo and in vitro of nonresponder strains (bearing the H-2(s), H-2(q), and H-2(p) haplotypes) to GAT complexed with an immunogenic carrier, methylated bovine serum albumin, MBSA (1,2). We then extended these findings to another antigen, the copolymer of L-glutamic acid and L-tyrosine (GT). None of 19 inbred or congenic resistant mouse strains developed antibody responses to GT after immunization with this synthetic polypeptide in adjuvants. All the strains investigated, however, developed IgG plaque-forming cells (PFC) primary responses to GT complexed with MBSA (3). This permitted us to determine that: (a) preimmunization with GT suppressed the response to GT-MBSA in certain but not in all strains; (b) the suppression could be transferred by thymocytes and spleen cells from GT-primed animals; (c) the development of GT-specific suppressor cells is under dominant control of H-2- linked gene(s) which have been designated specific immune suppressor genes (Is genes); (d) the Is genes are antigen specific since GAT-MBSA responses are suppressed by GAT in strains carrying the H-2(q) haplotype, while GT-MBSA responses are not suppressed by the related polymer GT in these same strains (3,4). The experiments reported in this study map the Is genes responsible for GT-specific suppression within the H-2 complex. The data indicate that the K and D loci are not concerned with GT-specific suppression, and that this phenomenon is controlled by complementing or interacting genes which map on either side of cross-over events between the IB and IC subregions.

Genetic control of specific immune suppression. I. Experimental conditions for the stimulation of suppressor cells by the copolymer L-glutamic acid50-L-tyrosine50 (GT) in nonresponder BALB/c mice.

In the present studies we have confirmed that the random copolymer of L-glutamic acid50-L-tyrosine50 (GT) fails to induce an antibody response in a large number of inbred strains of mice. Nevertheless, GT complexed to methylated bovine serum albumin (MBSA) elicits a GT-specific IgG PFC response in vivo. Furthermore, injection of BALB/c mice with 10 to 100 mug of GT specifically decreases their ability to develop anti-GT PFC responses to a subsequent challenge with GT-MBSA. GT-specific tolerance can be transferred to normal, syngeneic recipients by spleen cells or thymocytes of GT-primed animals. These results indicate that the stimulation of suppressor cells can be observed in nonresponder mice with another synthetic polypeptide besides GAT. Various parameters of GT-specific immunosuppression in BALB/c mice are described. The application of these techniques to the study of the genetic factors controlling the stimulation of specific immune suppression is discussed.

Genetic control of specific immune suppression. IV. Responsiveness to the random copolymer L-glutamic acid50-L-tyrosine50 induced in BALB/c mice by cyclophosphamide.

Previous reports from our laboratory have demonstrated the stimulation of specific suppressor T cells in genetic nonresponder mice after immunization with the terpolymer of L- glutamic acid, L-alanine, and L-tyrosine (GAT) (1,2) and with the copolymer of L-glutamic acid and L-tyrosine (GT) (3-5). These findings raise two important questions: (a) do the specific suppressor T cells inhibit an antibody response which would otherwise develop in nonresponder mice; and, (b) can specific helper T cells inhibit an antibody response which would otherwise develop in nonresponder mice; and, (b) can specific helper T-cell activity be detected in these animals. Responsiveness appears to be completely dominant over suppression in (responder x suppressor)F(1) hybrids, therefore, we have been unable to detect suppressor cells in these hybrids after conventional immunization with GAT (2). However , using special conditions of antigen administration, GAT helper activity could be demonstrated in nonresponder DBA/1 ("suppressor") mice. Thus, GAT-specific helper activity was not detected in these nonresponder animals after immunization with GAT irrespective of the adjuvant used, but could be stimulated by macrophage-bound GAT or by GAT complexed with methylated bovine serum albumin GAT-MBSA (6). In the current report we have taken advantage of the fact that suppressor T-cell activity is more sensitive to cyclophosphamide treatment than T-cell helper activity (7) to demonstrate the presence of GT-specific helper activity in "nonresponder" BALB/c mice. We describe: (a) the dose of cyclophosphamide and conditions of treatment which inhibits the well-documented stimulation of specific suppressor T cells in BALB/c mice injected with GT previous to immunization with GT-MBSA, and (b) the ability of cyclophosphamide to permit the development of primary PFC responses to GT in these "nonresponder" mice. These cyclophosphamide-induced responses are not characterized by the high levels of antibody detected in genetic responder animals.

Genetic control of specific immune suppression. II. H-2-linked dominant genetic control of immune suppression by the random copolymer L-glutamic acid50-L-tyrosine50 (GT).

Several inbred as well as congenic resistant strains of mice, which fail to respond to the random copolymer of L-glutamic acid50-L-tyrosine50 (GT), were shown to develop specific PFC responses when stimulated by GT complexed to an immunogenic carrier such as methylated bovine serum albumin (MBSA). In these studies we have found that GT preimmunization has a tolerogenic effect on the response to GT-MBSA in some mouse strains; whereas in other strains of mice, GT fails to inhibit the GT-MBSA response. We may, therefore, conclude that immune suppression cannot account for nonresponsiveness in all cases. The development of specific immune suppression in response to GT was shown to be inherited as a dominant trait in F1 hybrids resulting from the mating of suppressor with nonsuppressor strains. This trait is, therefore, under the control of a gene or genes that we have designated as specific immune suppression gene(s) Is genes. The strain distribution of GT induced suppression demonstrates that Is genes are coded for in the H-2 complex. Furthermore, immune suppression by the two related copolymers, GT and GAT, are distinct in different strains of mice. The significance of these data for our understanding of the regulation of the immune response is discussed.

Interleukin 4 counteracts the interleukin 2-induced proliferation of monoclonal B cells.

B cells from patients suffering from B-type chronic lymphocytic leukemia (B-CLL) are susceptible to the effects of several interleukins. Using the cells from 12 different patients we show that IL-4 does not synergize with anti-mu antibody for the enhancement of DNA synthesis. Moreover IL-4 profoundly (90%) suppresses the response to IL-2 in the 10 patient responders to this interleukin. This suppression occurs whether IL-2 is used alone, in costimulation with anti-mu antibody, or in synergy with IFN-gamma. In no instance did IL-4 induce terminal differentiation. This negative effect of IL-4 can take place in monoclonal B-CLL cells where IL-4 enhances the expression of CD23. IL-4 does not interfere with the upregulation of CD25 by IL-2. Thus, IL-4 may display inhibitory effects on the proliferative response of selected B cell populations. The antagonism between IL-4 and IL-2 has important implications for the potential use of cytokines in the management of B-CLL patients.

HIV-specific T cell cytotoxicity mediated by RANTES via the chemokine receptor CCR3.

CC chemokines produced by CD8(+) T cells are known to act as HIV-suppressive factors. We studied the possible role of these chemokines in HIV-1-specific killing of target cells. We found that the activity of cytotoxic T lymphocytes (CTLs) in CTL lines or freshly isolated peripheral blood mononuclear cells from HIV-1-infected individuals is markedly enhanced by RANTES (regulated on activation, normal T cell expressed and secreted) and virtually abolished by an antibody neutralizing RANTES or the RANTES receptor antagonist RANTES(9-68). Lysis was mediated by CD8(+) major histocompatibility complex class I-restricted T cells and was obtained with target cells expressing epitopes of the HIV-1LAI proteins Gag, Pol, Env, and Nef. The cytolytic activity observed in the presence or absence of added RANTES could be abolished by pretreatment of the CTLs with pertussis toxin, indicating that the effect is mediated by a G protein-coupled receptor. The chemokines monocyte chemotactic protein (MCP)-3, MCP-4, and eotaxin acted like RANTES, whereas macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, MCP-1, and stromal cell-derived factor 1 were inactive, suggesting a role for the eotaxin receptor, CCR3, and ruling out the involvement of CCR1, CCR2, CCR5, and CXCR4. CTL activity was abrogated by an antibody that blocks CCR3, further indicating that specific lysis is triggered via this chemokine receptor. These observations reveal a novel mechanism for the induction of HIV-1-specific cytotoxicity that depends on RANTES acting via CCR3.

Sequences and diversity of human T cell receptor beta chain variable region genes.

The nucleotide sequences of 22 human T cell antigen receptor (TcR) beta chain variable region genes isolated from various T lymphocytes have been analyzed. Of the 19 variable gene segment (V beta)-containing sequences, 17 were unique. The V beta gene segments were grouped into 11 families. Comparisons were made with the data of Concannon et al. to unify the nomenclature. The data is consistent with a total V beta gene segment repertoire with a most probable value of 38 members and an upper bound of 104 members at the 95% confidence level. Southern blot data of germline DNA using selected TcR V beta cDNAs as probes support this estimate. The human repertoire is approximately three to four times greater than that reported for the mouse. Explanations for this discrepancy are proposed.

Soluble CD23 (Fc epsilon RII) and interleukin 1 synergistically induce early human thymocyte maturation.

The ability of human thymus-derived CD7+CD2-CD3- cells to acquire mature T cell antigens was assessed. Purified CD7+ thymocytes were incubated with rIL-1, rIL-2, and/or recombinant soluble CD23 (rsCD23). Short-term incubation of these cells with only rsCD23 + rIL-1 induced mature T cell antigen expression on at least half of the cells. The induction of CD2 was functionally significant, as these cells became able to respond to CD2 triggering and could proliferate in response to IL-2. Possible sources of CD23 in the thymus are under investigation.

Positive effects of combined antiretroviral therapy on CD4+ T cell homeostasis and function in advanced HIV disease.

Highly active antiretroviral therapy (HAART) increases CD4(+) cell numbers, but its ability to correct the human immunodeficiency virus (HIV)-induced immune deficiency remains unknown. A three-phase T cell reconstitution was demonstrated after HAART, with: (i) an early rise of memory CD4(+) cells, (ii) a reduction in T cell activation correlated to the decreasing retroviral activity together with an improved CD4(+) T cell reactivity to recall antigens, and (iii) a late rise of "naïve" CD4(+) lymphocytes while CD8(+) T cells declined, however, without complete normalization of these parameters. Thus, decreasing the HIV load can reverse HIV-driven activation and CD4(+) T cell defects in advanced HIV-infected patients.

Rapid progression to AIDS in HIV+ individuals with a structural variant of the chemokine receptor CX3CR1.

Human immunodeficiency virus (HIV) enters cells in vitro via CD4 and a coreceptor. Which of 15 known coreceptors are important in vivo is poorly defined but may be inferred from disease-modifying mutations, as for CCR5. Here two single nucleotide polymorphisms are described in Caucasians in CX3CR1, an HIV coreceptor and leukocyte chemotactic/adhesion receptor for the chemokine fractalkine. HIV-infected patients homozygous for CX3CR1-I249 M280, a variant haplotype affecting two amino acids (isoleucine-249 and methionine-280), progressed to AIDS more rapidly than those with other haplotypes. Functional CX3CR1 analysis showed that fractalkine binding is reduced among patients homozygous for this particular haplotype. Thus, CX3CR1-I249 M280 is a recessive genetic risk factor in HIV/AIDS.

Transient depletion of dividing T lymphocytes in mice induces the emergence of regulatory T cells and dominant tolerance to islet allografts.

We previously showed that transient depletion of dividing T cells at the time of an allogeneic transplantation induces long-term tolerance to the allograft. Here we investigated the role of homeostatic perturbation and regulatory T cells (Treg) in such tolerance. Transient depletion of dividing T cells was induced at the time of an allogeneic pancreatic islets graft, by administration of ganciclovir for 14 days, into diabetic transgenic mice expressing a thymidine kinase (TK) conditional suicide gene in T cells. Allograft tolerance was obtained in 63% of treated mice. It was not due to global immunosuppression, permanent deletion or anergy of donor-alloantigens specific T cells but to a dominant tolerance process since lymphocytes from tolerant mice could transfer tolerance to naïve allografted recipients. The transient depletion of dividing T cells induces a 2- to 3-fold increase in the proportion of CD4(+)CD25(+)Foxp3(+) Treg, within 3 weeks that persisted only in allograft-bearing mice but not in nongrafted mice. Tolerance with similar increased proportion of Treg cells was also obtained after a cytostatic hydroxyurea treatment in normal mice. Thus, the transient depletion of dividing T cells represents a novel means of immuno-intervention based on disturbance of T-cell homeostasis and subsequent increase in Treg proportion.

Human immunodeficiency virus-1 glycoproteins gp120 and gp160 specifically inhibit the CD3/T cell-antigen receptor phosphoinositide transduction pathway.

The interference of the recombinant HIV-1 glycoproteins gp160 and gp120 with the CD3/T cell antigen receptor (TcR)-mediated activation process has been investigated in the CD4+ diphtheria toxoid-specific human P28D T cell clone. Both glycoproteins clearly inhibit the T cell proliferation induced in an antigen-presenting cell (APC)-free system by various cross-linked monoclonal antibodies specific for the CD3 molecule or the TcR alpha chain (up to 80% inhibition). Biochemical studies further demonstrate that exposure of the T cell clone to both glycoproteins (gps) specifically inhibits the CD3/TcR phospholipase C (PLC) transduction pathway, without affecting the CD3/TcR cell surface expression. Thus, inositol phosphate production, phosphatidic acid turnover, intracellular free calcium, and intracellular pH increase induced by CD3/TcR-specific MAbs are specifically impaired in gps-treated P28D T cells. Addition of purified soluble CD4 prevents binding of gps to T cells and overcomes all observed inhibitions. Maximal inhibitions are obtained for long-term exposure of the T cell clone to gps (16 h). No early effect of gps is observed. By contrast, gp160 and gp120 fail to suppress the CD2-triggered functional and biochemical P28D T cell responses. These results demonstrate that, in addition to their postulated role in the alteration of the interaction between CD4 on T lymphocytes and MHC class II molecules on APC, soluble HIV-1 envelope glycoproteins may directly and specifically impair the CD3/TcR-mediated activation of PLC in uninfected T cells via the CD4 molecule.

Epidermal keratinocyte-derived basophil promoting activity. Role of interleukin 3 and soluble CD23.

Human epidermal keratinocytes (EK) secrete factors able to sustain the proliferation of early myeloid cells and, in particular, the generation of basophils. This activity was previously attributed to IL-3, although no definitive in situ demonstration of this cytokine was provided. In regard to the possible physiological relevance of these data, we investigated herein the nature of EK-derived factors responsible for basophil promotion. Our data show that EK-derived supernatants (EK-sup) contain IL-3 as well as soluble CD23 (sCD23), both known for their colony stimulating activity. Messenger RNA for IL-3 and CD23 were also detected in EK. Blocking experiments using specific neutralizing monoclonal antibodies (mAb) further indicate that EK-derived basophil promoting activity is mainly due to the presence of IL-3 and sCD23 in EK-sup. Furthermore, by contrast to IL-3, sCD23 secretion by EK is cortisone sensitive and highly enhanced by IL-4, suggesting distinct regulatory mechanisms for their production.

Carboxyl-terminal and central regions of human immunodeficiency virus-1 NEF recognized by cytotoxic T lymphocytes from lymphoid organs. An in vitro limiting dilution analysis.

Cytotoxic T lymphocytes (CTL) specific for human immunodeficiency virus (HIV) proteins have been analyzed in lymphoid organs from seropositive patients. Indeed, an active HIV replication coexists with a major CD8+ lymphocytic infiltration in these organs. We have shown in a previous report that HIV-seropositive patients lungs were infiltrated by HIV specific CD8+ lymphocytes. In the present report, we show that HIV-specific CTL responses can also be detected in lymph nodes and spleens, and were mainly directed against the ENV, GAG, and NEF HIV-1 proteins. The primary NEF-specific CTL responses were further characterized by epitope mapping. Determination of epitope-specific CTL frequencies were performed by limiting dilution analysis. Our results indicated that, in addition to the central region of NEF (AA66-148), a new immunodominant region is recognized by CTL. This region corresponds to the carboxyl-terminal domain of NEF (amino acids 182-206). AA182-206 is recognized in association with at least two common human histocompatibility leukocyte antigen (HLA) molecules (HLA-A1 and B8), with clonal frequencies of one CTL per 10(-5) to 10(-6) splenic lymphocytes. Our data indicate that lymphoid organs may represent a major reservoir for in vivo activated HIV-specific CTL. Furthermore, the carboxyl-terminal domain of NEF was found to be conserved among several HIV strains. Therefore, our finding is of interest for further HIV vaccines development.