Defective T-cell colony formation and IL-2 receptor expression at all stages of HIV infection.

The T-cell colony assay is a highly sensitive measure of immunological dysfunction. The present study evaluated this in vitro response in asymptomatic HIV-infected homosexuals, those with chronic adenopathy as their only clinical manifestation and patients with either ARC or AIDS. The mean colony count in antibody-positive asymptomatic individuals was significantly reduced when compared to either heterosexual controls or antibody-negative homosexuals. Furthermore, there were no differences in the responses of these antibody-positive individuals and those with chronic lymphadenopathy as their only clinical manifestation. By contrast, patients with AIDS or ARC showed a profound defect; this suggests that the colony assay can detect a functional gradient across the spectrum of HIV infections. Colony growth was correlated with the absolute number of T-helper cells and the ability of PHA-stimulated lymphocytes to express IL-2 receptors; no correlation was found with the number of suppressor/cytotoxic cells or in vitro production of IL-2. Recent HIV seroconverters had normal colony counts but impaired ability to express IL-2 receptors. These data suggest a sequential loss of T-cell function as a result of HIV infection; the earliest manifestations are impaired expression of IL-2 receptors and reduced proliferative responses, as measured in the colony assay.     

Autologous mixed lymphocyte reaction in man. XIV. Deficiency of the autologous mixed lymphocyte reaction in acquired immune deficiency syndrome (AIDS) and AIDS related complex (ARC). In vitro effect of purified interleukin-1 and interleukin-2.

Peripheral blood mononuclear cells from male homosexuals with acquired immune deficiency syndrome (AIDS) and with AIDS related complex (ARC) were examined for the autologous mixed lymphocyte reaction (AMLR) between responder T and irradiated autologous non-T cells and in vitro influence of purified human interleukin-1 (IL-1) and -2 (IL-2) on the AMLR. The AMLR was significantly (P less than 0.001) deficient in both ARC and AIDS; the deficiency of the AMLR was of the similar magnitude in two groups when compared to asymptomatic homosexuals and healthy heterosexuals. In vitro addition of IL-2 enhanced the AMLR to the baseline levels of control subjects in most patients in ARC group (P less than 0.01) and in four of 15 patients in AIDS group (P less than 0.01). Addition of IL-1 to IL-2 containing cultures resulted in no further increase in the AMLR response over those with IL-2 alone. This study demonstrates deficiency of the AMLR in patients with ARC and AIDS that is corrected by purified IL-2 in the majority of cases with ARC but only a subset of patients with AIDS. The significance of these findings is discussed.     

Analysis of lymphocyte cell death and apoptosis in HIV-2-infected patients.

Recent evidence suggests that T cell apoptosis could be involved in the pathogenesis of HIV-1 infection. As the progression of HIV-2 associated disease appears to be slower than that of HIV-1, we investigated whether there were differences in the degree of T cell death and apoptosis in peripheral blood mononuclear cell (PBMC) cultures from patients with HIV-1 or HIV-2 infection. PBMC from healthy controls (n = 28) and patients infected with HIV-1 (n = 26: asymptomatic (ASY)/persistent generalized lymphadenopathy (PGL), n = 16; and AIDS-related complex (ARC)/AIDS n = 10) or HIV-2 (n = 30: ASY/PGL, n = 16; ARC/AIDS, n = 14) were cultured in the absence or presence of mitogens (PHA, PWM) or superantigen (SEB). After 48 h, cell death (CD) was assessed by trypan blue exclusion and in some patients programmed cell death (PCD) was quantified in flow cytometry by measuring the percentage of hypodiploid nuclei corresponding to fragmented DNA, after treating the cells with a propidium iodide hypotonic solution. HIV-1 and HIV-2 ARC/AIDS patients and ASY/PGL HIV-1+ patients had significant increases in cell death percentages compared with controls, both in unstimulated and stimulated lymphocyte cultures. However, HIV-2+ ASY/PGL patients did not exhibit significant increases of cell death in unstimulated cultures. In addition, the comparison between HIV-1 and HIV-2 infected subjects in similar stages of disease, showed no significant differences in CD in the ARC/AIDS patients, although ASY/PGL HIV-2 infected subjects had lower levels of CD than the HIV-1+ ASY/PGL (3.4% +/- 0.6 s.e.m. versus 6.8% +/- 1.1 s.e.m., P < 0.01). PCD was significantly increased both in ASY/PGL (14.3% +/- 2.2 s.e.m., n = 8, P < 0.005) and in ARC/AIDS (25.3% +/- 4.5 s.e.m., n = 9, P < 0.001) HIV-1+ patients compared with healthy controls (5.8% +/- 1.7 s.e.m., n = 11). This contrasts with HIV-2 infected subjects where the ASY/PGL patients (10.0% +/- 2.8 s.e.m., n = 6) did not differ significantly from healthy controls, although ARC/AIDS patients (27.2% +/- 4.2 s.e.m., n = 9, P < 0.001) had significantly increased levels of PCD. In conclusion, this is the first report describing the occurrence of spontaneous and activation-induced lymphocyte death by apoptosis in HIV-1 infected subjects.(ABSTRACT TRUNCATED AT 400 WORDS)     

Altered immunoregulation and autoimmune aspects of HIV infection: relevant murine models

After initial infection with human immunodeficiency virus 1 (HIV-1), patients may remain asymptomatic for years before the onset of acquired immune deficiency syndrome (AIDS). This non-aggressive or latent phase may be manifested by functional abnormalities of both T and B cells, even in the absence of critical reductions in lymphocyte numbers. At present, it is not clear whether the immune abnormalities in either the asymptomatic phase or in clinical AIDS are due solely to direct effects of HIV-1 or whether they also reflect host immunoregulatory mechanisms. In this article, by Charles Via, Herbert Morse and Gene Shearer, the immune abnormalities associated with early HIV-1 infection are compared with immune abnormalities found in three murine models of autoimmunity and immunodeficiency, and it is suggested that host mechanisms contribute to defective helper T (TH)-cell function early in the course of HIV-1 infection. Furthermore, two murine models appear relevant to the study of late HIV-1 infection and suggest a role for CD8+ T cells in the prevention of symptomatic AIDS.     

During HIV-1 infection most blood dendritic cells are not productively infected and can induce allogeneic CD4+ T cells clonal expansion.

We have considered the possibility that antigen-presenting cells of the dendritic cell lineage may be infected in vivo and spread HIV-1 at the time dendritic cells initiate the clonal expansion of antigen-specific T cells. Dendritic cells were isolated from 25 HIV-1-infected subjects (CDC stages II-IV). Fewer dendritic cells were recovered from most infected subjects. Reduced numbers of total non-T cells were also found in these patients, so that preferential loss of dendritic cells did not occur. Dendritic cell function was assessed by stimulatory capacity for allogeneic CD4+ T cells in the mixed leucocyte reaction (MLR). Potent MLR stimulator activity was retained in the dendritic cell-enriched populations from HIV-infected patients. Seven out of nine patients without AIDS (asymptomatic, lymphadenopathy or ARC) and three out of six patients with AIDS had proliferative responses equivalent to those induced by dendritic cells from controls. Dendritic cells from HIV+ subjects were able to initiate the expansion of allogeneic CD4+ T cell clones with cloning efficiency not different from controls and without evidence of cytopathic effect in the expanding CD4+ clones. In situ hybridization of the different mononuclear cell populations with a gag-specific riboprobe demonstrated positive cells in the T cell fractions of 12 of the 15 patients tested. None of the asymptomatic or ARC patients had riboprobe-positive cells in the dendritic cell-enriched populations. Four out of nine patients with AIDS had cells positive for HIV-1 expression in the dendritic cell-enriched fraction. However, the positive cells had the nuclear profile of lymphocytes, and by cytofluorography some residual low-density T cells were present. By limiting dilution and polymerase chain reaction (PCR), CD4+ lymphocytes carried HIV provirus in inocula of 500-5000 cells, while provirus could only be detected in 50,000 cells from the dendritic cell-enriched fraction. The latter signal may be due to the demonstrated levels of T cell contamination. Our data indicate that productive or latent HIV-1 infection of blood dendritic cells in vivo is rare, certainly no greater than in T lymphocytes, and that in vitro dendritic cell preparations from patients can expand CD4+ T cells efficiently and therefore may be able to expand T cells with immunotherapeutic activity.     

Effects of interleukin 2 and large envelope glycoprotein (gp 120) of human immunodeficiency virus (HIV) on lymphocyte proliferative responses to cytomegalovirus.

Lymphocytes from many HIV-infected asymptomatic individuals or patients with AIDS-related conditions (ARC) and from all AIDS patients were unable to proliferate in vitro in response to UV-inactivated cytomegalovirus (CMV). The addition of recombinant IL2 (rIL2) restored proliferative responses of lymphocytes from most HIV-infected asymptomatic individuals and ARC patients to levels similar to those of HIV-seronegative (HIV-) CMV-seropositive (CMV+) individuals. In contrast, rIL2 augmented CMV-specific lymphocyte proliferation of only 33% (6/18) of AIDS patients. Proliferative responses to CMV with or without rIL2 did not correlate well with the levels of CD4+ lymphocytes, HIV antigen levels or ratios of CD4+ and CD8+ lymphocytes. Proliferative responses to CMV were inhibited by relatively high concentrations (greater than or equal to 10 micrograms/ml) of recombinant HIV envelope glycoprotein (rgp120) and this immunosuppression was completely overcome by rIL2. These results indicate that defects in antigen-driven lymphocyte responses of HIV-infected individuals are not simply the result of reduced numbers of CD4+ lymphocytes but are influenced by defects in IL2 pathways and by immunosuppressive effects of HIV gp120.     

Is there correlation of T cell proliferative functions and surface marker phenotypes in patients with acquired immune deficiency syndrome or lymphadenopathy syndrome?

We have investigated the respective role of quantitative T lymphocyte subset abnormalities, interleukin-2 (IL-2) production and responsiveness to IL-2, in the proliferative deficiency that is observed in acquired immune deficiency syndrome (AIDS) and Lymphadenopathy syndrome (LAS) patients or even in some apparently healthy male homosexuals. 83 subjects were evaluated: 35 symptom free male homosexuals (HC), 24 LAS and 24 AIDS patients. As expected, many HC and most patients presented with T lymphocyte subset imbalance. These quantitative defects were associated with decreased reactivity to PHA and reduced production of IL-2 by PHA stimulated lymphocytes. No correlation however could be found between these two functions and variations in the T lymphocyte subset distribution. On the other hand, PHA responsiveness appeared to closely depend on IL-2 activity. Addition of exogenous IL-2 to lymphocytes from patients with low proliferative responses, stimulated with suboptimal PHA concentration, enhanced proliferation in some but not all the cases. In most instances this increase never reached the levels observed with similarly treated cells from normal individuals. In these patients, the limited number of lymphocytes which express IL-2 receptors upon PHA stimulation may explain both low PHA reactivity and reduced IL-2 responsiveness. These data indicate some possible mechanisms of immunodeficiency in AIDS and LAS.     

Human immunodeficiency virus (HIV)-2-specific T lymphocyte proliferative responses in HIV-2-infected and in HIV-2-exposed but uninfected individuals in Guinea-Bissau

Human immunodeficiency virus (HIV)-2-specific T lymphocyte proliferative responses were determined in cultures of peripheral blood mononuclear cells from HIV-2-exposed uninfected individuals, HIV-2-infected individuals and HIV-negative controls in Guinea-Bissau. Increased HIV-2-specific T lymphocyte proliferative responses were detected in both groups compared to HIV-negative controls (healthy HIV-uninfected individuals without known exposure to an HIV-infected person); five out of 29 of the HIV-2-exposed uninfected and half (16 of 32) of the HIV-2-infected individuals had stimulation indexes >2, compared to one out of 49 of the HIV-negative controls (P = 0.003 and P < 0.0001, respectively). The exposed uninfected individuals had reactivity to a HIV-2 V3-peptide corresponding to amino acids 311-326 of the envelope glycoprotein, while the HIV-2-infected people reacted mainly to HIV-2 whole viral lysate. Thus, this study demonstrates a high degree of HIV-2-specific T helper cell activity, as measured by lymphocyte proliferation, in HIV-2-exposed uninfected individuals as well as in HIV-2-infected subjects. These immune responses could be important for resistance to the infection and for the control of established infection and, thus, play a role in the lower transmission and progression of HIV-2 compared to HIV-1.     

Study of activated T cells in man. II. Interleukin 2 receptor and transferrin receptor expression on T cells and production of interleukin 2 in patients with acquired immune deficiency syndrome (AIDS) and AIDS-related complex

Because the expression of interleukin 2 (IL-2) receptor and transferrin receptor is essential for the proliferation of T cells to mitogens and antigens, we examined the expression of monoclonal antibody defined IL-2 receptor (Tac antigen) and transferrin receptor on unstimulated as well as on phytohemagglutinin (PHA)-activated highly enriched T cells from patients with acquired immune deficiency syndrome (AIDS) and AIDS-related complex (ARC). A trend of increased proportion of unstimulated T cells with Tac antigen and transferrin receptor was observed in patients with AIDS and ARC when compared to healthy heterosexual controls, but the differences were not significantly (P greater than 0.1). The proportions of Tac+ PHA-activated T cells were, however, significantly decreased in AIDS (P less than 0.001). ARC (P less than 0.001), and asymptomatic homosexuals (P less than 0.01) when compared to healthy heterosexuals. The proportions of transferrin receptor positive PHA-activated T cells were not significantly different among various groups. A significantly (P less than 0.01) decreased production of IL-2 was observed in AIDS. This study suggests that the poor proliferative responses of T cells may be due to several defects in lymphocyte-cytokine cascade and the deficiency of Tac antigen expression and of the production of IL-2 could be a few of several abnormalities contributing to poor T-cell functions in AIDS.     

Induction of HIV-1-specific T cell responses by administration of cytokines in late-stage patients receiving highly active anti-retroviral therapy.

Highly active anti-retroviral therapy (HAART) is associated with reduction in the morbidity and mortality of patients with advanced HIV-1 disease. The ability of such treatment to improve immune responses against HIV-1 and opportunistic pathogens is variable and limited. Addition of cytokine immunotherapy to this treatment may improve immune responses. IL-2 with or without granulocyte-macrophage colony-stimulating factor (GM-CSF) was administered to HIV-1+ individuals receiving HAART with undetectable viral loads, and CD4 counts < 100 cells/microl. In one patient presenting with Mycobacterium avium complex (MAC) infection, we evaluated the effect of cytokine immunotherapy on lymphocyte phenotype; plasma viral load; proliferative responses to mitogens, recall and HIV-1 antigens; cytokine production and message in response to non-specific and specific stimuli; and natural killer (NK) cell activity. Proliferation assays were performed in two similar patients. Before cytokine immunotherapy the predominant CD8+ population was mainly CD28-. No proliferation or IL-2 production was seen in response to mitogens, recall or HIV-1 antigens; and no HIV-1 peptide-specific interferon-gamma (IFN-gamma)-secreting cells were present. Low levels of IL-4 were detected in response to antigens to which patients had been exposed, associated with up-regulated expression of costimulatory molecules influenced by IL-4. Following IL-2 administration, loss of IL-4 was associated with increased NK cell activity and HIV-1 peptide-specific and non-specific IFN-gamma-producing cells. Proliferative responses associated with IL-2 production and responsiveness were only seen after subsequent concomitant administration of GM-CSF with IL-2. These changes mirrored clinical improvement. An imbalance of lymphocyte subsets may account for immune unresponsiveness when receiving HAART. Restoration of responses following immunotherapy suggests a shift towards a lymphocyte profile with anti-pathogen activity.     

Lymphocyte transformation responses to phytohaemagglutinin and pokeweed mitogen in patients at differing stages of HIV infection: are they worth measuring?

AIMS--To determine whether the routine measurement of lymphocyte transformation responses to mitogenic stimuli provide any information additional to that available from routine T cell CD4 and CD8 analysis in patients with HIV infection. METHODS--The case records of 197 immunologically investigated HIV seropositive patients were reviewed. The influence of disease stage on T lymphocyte subsets and lymphocyte transformation responses (LyTR) to phytohaemagglutinin (PHA) and Pokeweed mitogen was assessed. RESULTS--The median CD3 and CD4 counts and LyTR to PHA and Pokeweed mitogen were highest in patients with persistent generalised lymphadenopathy (PGL) and decreased progressively in the order: asymptomatic patients, those with ARC, those with AIDS. LyTR to PHA was preserved in over 70% of all patients, but the response to Pokeweed mitogen was depressed in 8% of patients with PGL, 34% of asymptomatic patients, 68% of those with ARC and 78% of those with AIDS. Subnormal values of both CD4 + T cells and LyTR to Pokeweed mitogen were more common in patients with ARC and AIDS (68%) than in those who were asymptomatic or had PGL (20%). CONCLUSIONS--CD4 T cell analysis and LyTR to Pokeweed mitogen, but not to PHA, both correlate with disease states in patients with HIV infection.     

Preservation of lymphocyte immunophenotype and proliferative responses in cryopreserved peripheral blood mononuclear cells from human immunodeficiency virus type 1-infected donors: implications for multicenter clinical trials. The ACTG Immunology Advanced Technology Laboratories

Human immunodeficiency virus type 1 (HIV-1) infection results in impaired immune function that can be measured by changes in immunophenotypically defined lymphocyte subsets and other in vitro functional assays. These in vitro assays may also serve as early indicators of efficacy when new therapeutic strategies for HIV-1 infection are being evaluated. However, the use of in vitro assays of immune function in multicenter clinical trials has been hindered by their need to be performed on fresh specimens. We assessed the feasibility of using cryopreserved peripheral blood mononuclear cells (PBMC) for lymphocyte immunophenotyping and for lymphocyte proliferation at nine laboratories. In HIV-1-infected patients with moderate CD4(+) lymphocyte loss, the procedures of density gradient isolation, cryopreservation, and thawing of PBMC resulted in significant loss of CD19(+) B cells but no measurable loss of total T cells or CD4(+) or CD8(+) T cells. No significant changes were seen in CD28(-) CD95(+) lymphocytes after cell isolation and cryopreservation. However, small decreases in HLA-DR(+) CD38(+) lymphocytes and of CD45RA(+) CD62L(+) were observed within both the CD4(+) and CD8(+) subsets. Fewer than 10% of those specimens that showed positive PBMC proliferative responses to mitogens or microbial antigens lost their responsiveness after cryopreservation. These results support the feasibility of cryopreserving PBMC for immunophenotyping and functional testing in multicenter AIDS clinical trials. However, small changes in selected lymphocyte subsets that may occur after PBMC isolation and cryopreservation will need to be assessed and considered in the design of each clinical trial.     

Expression of the alpha 5 beta 1 fibronectin receptor on T lymphocytes of patients with HIV-1 infection.

AIMS: To evaluate the expression of the alpha 5 beta 1 integrin fibronectin receptor (FNR), which mediates several processes, including phagocytosis, cell motility and the immune response, on T lymphocytes of patients with HIV-1 infection. METHODS: T lymphocytes were incubated with monoclonal antibody directed against FNR and then with monoclonal antibodies, conjugated with phycoerythrin, directed against CD3, CD4 and CD8 positive cells. Expression of FNR on CD3, CD4 and CD8 positive cells was analysed using flow cytometry. RESULTS: Normal expression of FNR was observed on CD3 positive cells from asymptomatic HIV positive patients and those with AIDS. Increased expression of FNR was observed on CD8 positive cells from asymptomatic HIV positive patients and on CD4 positive cells from patients with AIDS. Increased FNR expression was observed on CD4 positive cells from patients with AIDS, particularly those with opportunistic infections caused by Pneumocystis carinii, Mycobacterium sp, Toxoplasma gondii, and Cryptococcus neoformans. CONCLUSION: Increased expression of FNR on CD8 and CD4 positive cells in asymptomatic HIV positive patients and those with AIDS, respectively, may be an epiphenomenon correlated with lymphocyte activation by HIV-1 or opportunistic infection, Further study is required to determine whether upregulation of FNR expression has a direct role in the pathogenesis of AIDS.     

Disturbed immunoregulatory properties of the neuropeptide substance P on lymphocyte proliferation in HIV infection.

The neuropeptide substance P (SP) is known to increase cell-mediated immune responses in animal models and healthy subjects. Several studies have suggested an involvement of neuropeptides in the immunopathogenesis of some diseases. The study of the immunomodulatory effects of neuropeptides, namely SP, may represent a model for the analysis of immunoregulatory defects in HIV infection at the level of the interaction between the immune and nervous systems, both of which are known to be affected by the virus. In the present study, we investigate the possibility of a disturbance in the immunomodulatory properties of SP in HIV infection by analysing the effects of SP (10(-10)-10(-6) M) on the lymphocyte proliferative responses to concanavalin A (Con A) and phytohaemagglutinin (PHA) assessed by 3H-thymidine incorporation in peripheral blood lymphocytes from 34 HIV-infected patients (16 asymptomatic (ASY)/persistent generalized lymphadenopathy (PGL); 18 ARC/AIDS) and in 37 healthy subjects. In ASY/PGL HIV-infected patients, SP 10(-7) M was identified as the concentration inducing the maximal increase in the lymphocyte responses to Con A and PHA, similarly to what was observed in healthy subjects. In ARC/AIDS patients, SP appeared to inhibit the mitogenic responses, particularly those induced by Con A, in contrast to the effects found either in healthy subjects or in ASY/PGL patients. These results suggest the existence of an alteration in the in vitro immunomodulatory properties of SP in ARC/AIDS patients compared with healthy subjects and ASY/PGL patients. In conclusion, the unexpected finding of an inhibitory effect of SP on lymphocyte proliferation from ARC/AIDS patients justifies further investigation of the neuropeptide-dependent immunoregulatory systems in HIV infection.     

Abnormality of Leu 2+7+ cells in acquired immune deficiency syndrome (AIDS), AIDS-related complex,and asymptomatic homosexuals

Peripheral blood mononuclear cells from patients with acquired immune deficiency syndrome (AIDS) and AIDS-related complex (ARC), asymptomatic homosexuals, and healthy heterosexuals were analyzed for the proportions and numbers of Leu 7⁺ cells and double-labeled Leu 2⁺7⁺ cells and for the natural killer functions. A significant increase in the proportions and numbers of Leu 7⁺ cells was observed in patients with AIDS and ARC and in asymptomatic homosexuals compared to healthy heterosexual men. The proportions of Leu 2⁺7⁺ cells were significantly increased in AIDS, ARC, and asymptomatic homosexuals, whereas the numbers were increased in asymptomatic homosexuals and ARC but not in AIDS compared to heterosexual controls. A significant increase in the number of Leu 2⁺7⁺ cells was observed in AIDS with Kaposi's sarcoma but not in AIDS with opportunistic infections. The natural killer function was significantly depressed in patients with AIDS and ARC and in asymptomatic homosexuals. These data suggest that the quantitative abnormalities of Leu 2⁺7⁺ cells appear early during the evolution of immunologic changes in HTLV III/LAV infection.     

Immunophenotypic analysis of peripheral blood leukocytes at different stages of HIV infection. An analysis of asymptomatic, ARC, and AIDS populations

Blood leukocytes from 51 patients with acquired immune deficiency syndrome (AIDS) or AIDS-related syndrome (ARC) were immunophenotyped with the use of monoclonal antibodies and flow cytometry. The patients were placed into four clinically defined groups: HIV-positive asymptomatic (HIV+/A, 8); persistent generalized adenopathy (14); Kaposi's sarcoma (12); and opportunistic infections (17). Immunophenotypes were compared between groups. Statistically significant differences were seen in absolute lymphocyte counts, total T-cells, helper/inducer T-cells, the helper inducer subset of CD4+ lymphocytes, the suppressor inducer subset of CD4+ lymphocytes, activated helper T-cells, and natural killer cells. CD8+ cells and subsets were not statistically different between groups, possibly obscured by large ranges, but median values suggested differences. Results indicate a pattern of increasing or decreasing numbers of certain subpopulations as HIV infection progresses.     

Augmentation of mitogen-induced proliferative responses by in vitro indomethacin in patients with acquired immune deficiency syndrome and AIDS-related complex

The effect of indomethacin on mitogen-induced lymphocyte proliferative responses was studied in six normal heterosexual subjects and nine patients with the acquired immune deficiency syndrome (AIDS) and AIDS-related complex (ARC). Indomethacin enhanced only Con A-induced lymphocyte responses in six heterosexual men. In contrast, study of the cells from AIDS and ARC revealed that indomethacin enhanced PHA-induced lymphocyte proliferative responses from 52,600 counts/min to 70,900 counts/min (P less than 0.005) and 81,400 counts/min (P less than 0.001) at 0.1 and 1 microgram/ml. respectively and increased Con A-induced lymphoproliferation from 30,800 counts/min to 52,000 counts/min (P less than 0.01) at 0.1 microgram/mg and 51,1000 counts/min (P less than 0.005) at 1 microgram/ml. These results suggest that indomethacin enhanced mitogen-induced lymphoproliferative responses in vitro with cells from patients with AIDS and AIDS-related complex and may have therapeutic potential in some patients with AIDS.     

Reconstitution of CD4+ T cell responses in HIV-1 infected individuals initiating highly active antiretroviral therapy (HAART) is associated with renewed interleukin-2 production and responsiveness

Reconstitution of functional CD4(+) T cell responsiveness to in vitro stimuli is associated with continuous highly active antiretroviral therapy (HAART). Thirty-six antiretroviral naive patients received HAART over 16 weeks. Antigen-specific, mitogen and interleukin (IL)-2 induced lymphocyte proliferative responses and specific IL-2 and IL-4 production were assessed at each time-point, together with quantification of HIV-1 RNA load and lymphocyte populations. Reconstitution of recall responses was limited largely to persistent antigens such as Herpes simplex virus and Candida, rather than to HIV-1 or neo-antigens. Recall antigens, mitogens and IL-2-induced renewed responses were associated with in-vitro production of IL-2, but not IL-4. Differential responsiveness to low versus high concentration IL-2 stimulus increases in a stepwise manner, suggesting normalization of IL-2 receptor expression and improved functionality. These increases in in-vitro proliferative responses thus probably reflect short lived effector clones, driven by ongoing antigenic stimulus associated with persisting long-term organisms. In this context non-responsiveness to HIV-1 antigens suggests ongoing HIV-1 specific clonal T cell anergy.     

Selective loss of T cell functions in different stages of HIV infection Early loss ofanti-CD3-induced T cell proliferation followed by decreased anti-CD3-induced cytotoxic T lymphocyte generation in AIDS-related complex and AIDS

To investigate the effects of persistant human immunodeficiency virus (HIV) infectionon T cell reactivity, functional properties of peripheral blood T cells from HIV-seropositive homosexual men in various stages of infection were studied. T cell activationvia CD3 resulting in proliferation and differentiation was measured in a model system independent of accessory cells, using immobilized anti-CD3 monoclonal antibodies (mAb). T cells from HIV-infected asymptomatic men had a decreased proliferative response compared to HIV-negative controls. T cells from AIDS-related complex (ARC) and AIDS patients, compared to T cells from asymptomatic HIV-infected men, had a significantly lower proliferative response to anti-CD3 mAb. This diminished response to anti-CD3 mAb was shown to be due to decreased interleukin (IL)2 productionand could be enhanced by co-stimulation with anti-CD28 mAb or by adding IL2. Anti-CD3-induced generation of cytotoxic T lymphocytes was fully intact in early infection but was severely decreased in T cells from ARC and AIDS patients. Cytotoxic activity could be restored to near normal levels after co-stimulation with either anti-CD28 mAb or IL2. Our data demonstrate a differential loss of T cell functions in the course of HIV infection which is predominantly caused by a lack of IL2 production after stimulation via the CD3/T cell receptor complex. In early HIV infection this seems to be predominantly caused by a specific loss of memory T cells. However, in later stages of infection when both naive and memory T cell subsets are depleted, resultingin a normal naive/memory T cell ratio, T cell functions further deteriorate probably due to intrinsic activation defects. These findings may be of pathogenic relevance since diminished T cell reactivity may facilitate spreading and replication of virulent HIV variants heralding development of ARC and AIDS.     

Antibody to human immunodeficiency virus correlates with decreased T helper lymphocytes in asymptomatic individuals

To examine the relationship between human immunodeficiency virus (HIV) seropositivity and T lymphocyte subsets in a clinically well population, we assayed HIV antibody and analyzed T lymphocyte subsets in 30 people at increased risk for acquired immunodeficiency syndrome (AIDS) who were clinically well. Seventy-six percent of the HIV-seropositive individuals had abnormally low numbers of T helper lymphocytes, and HIV seropositivity was strongly correlated with an abnormally low number of T helper cells (p less than 0.00002). Among these clinically well subjects at increased risk for AIDS, HIV-sero-positive individuals had a significant decrease in mean T helper lymphocytes and mean T helper:T suppressor ratios as compared to those who were seronegative (483 cells/mm3 vs 915 cells/mm3, p less than 0.002; and 0.80 vs 1.7, p less than 0.002, respectively). Because of the strong correlation of HIV seropositivity and abnormally low numbers of T helper lymphocytes in this asymptomatic population, these findings suggest that asymptomatic seropositive individuals should be followed closely for development of AIDS-related disease and should be considered for future antiviral therapy when it becomes available.