Functional T lymphocyte immune deficiency in a population of homosexual men who do not exhibit symptoms of acquired immune deficiency syndrome

Lenalidomide enhancement of human T cell functions in human immunodeficiency virus (HIV)-infected and HIV-negative CD4 T lymphocytopenic patients

Suppressed T cell functions in human immunodeficiency virus (HIV) infection were identified and corrected by lenalidomide in middle-aged HIV-infected patients. Chemotaxis of T cells from HIV-infected men (n = 6, mean 43 years) to sphingosine 1-phosphate (S1P) and CCL21 was significantly lower than that of HIV-negative men (n = 6, mean 41 years), and was enhanced significantly up to control levels by 100 and 1000 nM lenalidomide. Generation of interleukin (IL)-2, but not interferon (IFN)-γ, by T cells of middle-aged HIV-infected men was significantly lower than that for controls and was increased significantly by 10-1000 nM lenalidomide up to a maximum of more than 300%. CD4 and CD8 T cells isolated from healthy middle-aged men and reconstituted in vitro at a low CD4 : CD8 ratio typical of HIV infection had depressed chemotaxis to S1P, but not CCL21, and generation of IL-2, but not IFN-γ. Significant enhancement of chemotaxis to S1P and CCL21 was induced by 100-1000 nM lenalidomide only for normal T cells at a low CD4 : CD8 ratio. T cells from HIV-negative middle-aged CD4 T lymphocytopenic patients (n = 3), with a CD4 : CD8 ratio as low as that of HIV-infected patients, had similarly diminished chemotaxis to S1P and CCL21, and depressed generation of IL-2, but not IFN-γ. Lenalidomide at 30-1000 nM significantly enhanced chemotaxis to S1P and IL-2 generation for T cells from HIV-negative CD4 T lymphocytopenic patients as from HIV-infected patients, with less effect on CCL21-elicited chemotaxis and none for IFN-γ generation. Defects in functions of T cells from middle-aged HIV-infected men are partially attributable to CD4 T lymphocytopenia and are corrected by lenalidomide.

Defective in vitro IL-2 production in lupus is an early but secondary event paralleling disease activity: evidence from the murine parent-into-F1 model supports staging of IL-2 defects in human lupus

T cell defects are a well described feature of both human and murine lupus however their exact significance is unclear. Evidence from an induced model of lupus, the P --> F1 model of chronic lupus-like GVHD demonstrates that a secondary inducible T cell defect in in vitro IL-2 and CTL responses occurs early in the course of lupus-like disease and well in advance of clinical disease. Defective Th cell function was probed using a novel approach categorizing the response to two stimuli:1) the MHC self restricted response, termed self +X; and 2) the allogeneic response. Using this approach, lupus mice exhibited similar in vitro Th cell pattern i.e. an absent S+X response but preserved allogeneic (termed -/+). In contrast, human lupus patients exhibited three possible response patterns, +/+, - /+ or -/- with more severe in vitro T cell impairment correlated with more severe disease. Similarly, patients with other T cell mediated conditions i.e. HIV infection or renal allograft recipients, also exhibited more severe in vitro T cell impairment with greater disease activity or greater immunosuppression respectively. The similar Th response patterns in human and murine T cell mediated conditions indicates that the underlying mechanisms involved are not disease specific but instead reflect common immune responses and validate the use of the P --> F1 model for future studies of T cell mediated conditions. These results support the use of prospective monitoring of IL-2 responses in lupus patients. Successful adaptation of this approach to the clinical setting could allow not only earlier therapeutic intervention and reduced organ damage but also earlier tapering of pharmacological agents and reduced untoward effects.

HIV-1 transgenic rat CD4+ T cells develop decreased CD28 responsiveness and suboptimal Lck tyrosine dephosphorylation following activation

Impaired CD4+ T cell responses, resulting in dysregulated T-helper 1 (Th1) effector and memory responses, are a common result of HIV-1 infection. These defects are often preceded by decreased expression and function of the alpha/beta T cell receptor (TCR)-CD3 complex and of co-stimulatory molecules including CD28, resulting in altered T cell proliferation, cytokine secretion and cell survival. We have previously shown that HIV Tg rats have defective development of T cell effector function and generation of specific effector/memory T cell subsets. Here we identify abnormalities in activated HIV-1 Tg rat CD4+ T cells that include decreased pY505 dephosphorylation of Lck (required for Lck activation), decreased CD28 function, reduced expression of the anti-apoptotic molecule Bcl-xL, decreased secretion of the mitogenic lympokine interleukin-2 (IL-2) and increased activation induced apoptosis. These events likely lead to defects in antigen-specific signaling and may help explain the disruption of Th1 responses and the generation of specific effector/memory subsets in transgenic CD4+ T cells.

Epitope Enhancement of a CD4 HIV Epitope toward the Development of the Next Generation HIV Vaccine

Virus-specific CD4+ T cell help and CD8+ cytotoxic T cell responses are critical for maintenance of effective immunity in chronic viral infections. The importance of CD4+ T cells has been documented in HIV infection. To investigate whether a stronger CD4+ T cell response can be induced by modifications to enhance the T1 epitope, the first CD4+ T cell epitope discovered in HIV-1-gp120, we developed a T1-specific CD4+ T cell line from a healthy volunteer immunized with a canarypox vector expressing gp120 and boosted with recombinant gp120. This T1-specific CD4+ T cell line was restricted to DR13, which is common in U.S. Caucasians and African-Americans and very frequent in Africans. Peptides with certain amino acid substitutions in key positions induced enhanced specific CD4+ T cell proliferative responses at lower peptide concentration than the original epitope. This relatively conserved CD4 epitope improved by the epitope enhancement strategy could be a component of a more effective second generation vaccine construct for HIV infection.

Role for HLA class II molecules in HIV-1 suppression and cellular immunity following antiretroviral treatment

HIV-1-infected patients treated early with combination antiretrovirals respond favorably, but not all maintain viral suppression and improved HIV-specific Th function. To understand if genetic factors contribute to this variation, we prospectively evaluated over 18 months 21 early-treated patients stratified by alleles of class II haplotypes. All seven subjects with the DRB1*13-DQB1*06 haplotype, but only 21% of other subjects, maintained virus suppression at every posttreatment measurement. Following HIV-1 p24 antigen stimulation, PBMCs from patients with this haplotype demonstrated higher mean lymphoproliferation and IFN-gamma secretion than did cells from patients with other haplotypes. Two DRB1*13-restricted Gag epitope regions were identified, a promiscuous one that bound its putative restriction element with nanomolar affinity, and another that mapped to a highly conserved region. These findings suggest that class II molecules, particularly the DRB1*13 haplotype, have an important impact on virologic and immunologic responses. The advantage of the haplotype may relate to selection of key HIV-1 Th1 epitopes in highly conserved regions with avid binding to class II molecules. Eliciting responses to the promiscuous epitope region may be beneficial in vaccine strategies.

Increased expression of CD80, CD86 and CD70 on T cells from HIV-infected individuals upon activation in vitro: regulation by CD4+ T cells

T cells express CD28 and CD27 which transduce co-stimulatory signals after interaction with their ligands on antigen-presenting cells (APC). These ligands, CD80, CD86 and CD70, are also expressed to some extent on activated T cells. Here, we show that in human immunodeficiency virus (HIV)-infected individuals, CD28 and CD27 expression is decreased on CD8+ T cells. On the other hand, T cell stimulation in vitro induced high CD80, CD86 and CD70 expression on T cells from HIV-infected individuals. It appeared that an inverted CD4:CD8 T cell ratio could explain this enhanced expression of co-stimulatory ligands. Indeed, high expression levels of CD80, CD86 and CD70 were found on activated CD8+ T cells from HIV- individuals cultured in the absence of CD4+ T cells. Addition of CD4+ T cells prevented this up-regulation. However, in HIV-infected individuals, addition of excess autologous or healthy control CD4+ T cells did not completely counteract up-regulation of co-stimulatory ligand expression on CD8+ T cells. Thus, to some extent, CD8+ T cells in HIV-infected individuals appeared to be refractory to CD4+ T cell-mediated regulation of ligand expression in vitro. Activated T cells from HIV-infected individuals and activated CD8+ T cells from healthy controls were able to act as accessory cells in CD3-induced T cell proliferation, which was dependent on cell-cell contact. Thus, we showed that T cells from HIV-infected individuals express enhanced levels of co-stimulatory ligands upon activation, which provides them with accessory cell properties. Enhanced stimulatory potential of these nonprofessional APC may contribute to persistently high levels of immune activation in HIV infection related to disease progression.

AIDS: a disease of impaired Th-cell renewal?

Individuals who are infected with human immunodeficiency virus (HIV) and develop AIDS are characterized by the progressive loss of T helper (Th) cells, together with an increase in virus load. Despite a remarkable similarity to humans, and their susceptibility to persistent HIV-1 infection, chimpanzees have a relative resistance to the development of AIDS. Here, Jonathan Heeney proposes that the critical underlying event perpetuating the progression to AIDS is the impairment of the immunological microenvironment necessary for competent, antigen-specific, Th-cell renewal. Survival is dependent on the host's ability to preserve the immunological infrastructure sufficiently in order to maintain the capacity for renewal of a balanced, competent Th-cell population.

Evidence for intact costimulation via CD28 and CD27 molecules in hyporesponsive T cells from human immunodeficiency virus-infected individuals

In the activation of T cells, the primary signal is antigen-specific and given through T cell receptor (TcR)/CD3 ligation. Furthermore, costimulatory molecules such as CD28 and CD27, provide an essential signal for activation through interaction with their ligands, present on the membrane of antigen-presenting cells. During asymptomatic human immunodeficiency virus (HIV)-1 infection, T cell function is progressively lost. Here, we investigated whether in the presence of impaired responses of T cells from HIV-infected individuals to signal one, costimulation through CD28 and CD27 after interaction with their natural ligands CD80 and CD70 is intact. T cell proliferative responses to signal one in combination with CD80 or CD70 were decreased in a large fraction of asymptomatically HIV-infected individuals. This was due to impaired responses of signal one but not to impaired responses to costimulation, since CD80 or CD70 did enhance signal one-mediated proliferative responses to a normal extent. Moreover, in individuals with proliferative responses to signal one that were decreased to 50% of normal T cell responses, costimulation even was increased compared to controls. Our results demonstrate that in HIV-infected individuals the response to costimulation is relatively preserved compared to responses to the first signal and point to the defect in T cells in HIV infection being primarily in the CD3/TcR-mediated pathway.

Systematic identification of T-cell activating epitopes on the human immunodeficiency virus type 1 envelope glycoprotein gp120 in primates immunized with synthetic peptides

Because T-cell responses are critical for defence against viral infections, an ideal vaccine should stimulate these cells. The authors have examined a series of forty overlapping synthetic peptides covering the entire amino acid sequence of the envelope protein gp120 from the human immunodeficiency virus type 1 (HIV-1) HTLV-IIIB isolate, for harbouring putative T-cell recognition sites. The peptide-induced proliferative responses and IL-2 production by blood mononuclear cells were studied from 40 macaques previously immunized with ovalbumin-conjugated HIV-1 peptide(s). These analyses disclosed four major areas of T-cell recognition, including one novel T-cell activating region (located between amino acids 152 and 176) which was also found to harbour a domain recognized by HIV-1 neutralizing antibodies. Recognition of the latter region by CD4+ T cells did not appear to be subject to strong genetic restriction. The results of these studies have obvious implications for the development of synthetic subunit vaccines against the acquired immunodeficiency syndrome (AIDS).

Humoral immune responses in human HIV-1 infection clearance of initial burst of virus replication and protection against disease progression

An attempt is made to summarize the evidence that humoral immune responses in natural HIV-1 infection play a role in clearance of the initial burst of replication as well as in protection against rapid disease progression. Therefore, the so-called "asymptomatic carrier state" was defined on the basis of immunological characteristics, such as CD4+ cell number, CD45RA-CD29+ cell number, CD4+ proliferative responses to anti-CD3 mAbs and soluble activation markers, as well as virological characteristics such as the state of the viral genome in the cell, levels of genomic RNA production, antigenemia, viremia and virus phenotype. During natural infection two major classes HIV-1 neutralizing and cell-fusion inhibiting antibodies are elicited. One population directed against mostly continuous epitopes localized in the third variable domain (V3) of the envelope and one against discontinuous epitopes of the envelope. The last population blocks gp120-CD4 attachment, the first does not. The role of each of these populations of functional antibodies, in the clearance of viremia and the maintenance of the asymptomatic carrier state is discussed.

A kinetic model of CD4+ lymphocytes with the human immunodeficiency virus (HIV)

This report describes a kinetic model of in vitro cytopathology involving interactions of human immunodeficiency virus (HIV) with CD4+ helper T lymphocytes. The model uses nonlinearly coupled, ordinary differential equations to simulate the dynamics of infected and uninfected cells and free virions. It is assumed that resting cells are more readily infected than activated cells, but once infected, only activated cells produce more virus. Resting cells can be activated by some appropriate stimulus (e.g. phytohemagglutinin, soluble antigen). The model predicts that the initial inoculum of virus is taken up by resting cells and without stimulation the system comes to a steady state of two populations, namely infected and uninfected cells. Stimulation of this system produces two additional populations, namely infected and uninfected activated cells which, along with the previous populations, exhibit cyclic behavior of growth, viral expression/release, and death. Additional stimuli enhance or diminish the cyclic behavior depending upon their occurrence in time. These simulations suggest a similar dynamics in human HIV infection and may explain a major factor responsible for the widely varying depletion rate of (CD4+) helper T cells in AIDS patients.

Human immunodeficiency virus genetic variation that can escape cytotoxic T cell recognition

In a longitudinal study of HIV seropositive patients, there were fluctuations in the specificity of cytotoxic T cells for the virus. This was matched by variability in proviral gag DNA epitope sequences in the lymphocytes of these patients. Some of these viral variants are not recognized by autologous T cells. Accumulation of such mutations in T-cell antigenic targets would provide a mechanism for immune escape.

Effect of HIV on antigen presentation by dendritic cells and macrophages

The antigen-presenting function of dendritic cells (DC) and macrophages (MO) following infection with HIV in vitro was examined. Using non-infected cells, DC, but not MO, stimulated primary proliferative responses in allogeneic lymphocytes in the mixed leukocyte reaction. Both DC and MO stimulated secondary responses to influenza virus and to tetanus toxoid in autologous T lymphocytes. After exposure of DC and MO to HIV1 in vitro for 2 days, 27% of DC but less than 1% MO became infected as assessed by in situ hybridization. DC were blocked in their capacity to stimulate responses to alloantigens or to the recall antigens. By contrast, MO retained the ability to stimulate responses to the recall antigens. Similar effects during in vivo infection would allow activated T-cell clones to respond to antigens presented by MO early in infection. However, any loss of activated T cells might prove cumulative and damaging in the absence of an effective DC recruitment mechanism for resting T cells.

Functional and phenotypic evidence for a selective loss of memory T cells in asymptomatic human immunodeficiency virus-infected men

In addition to a well-documented depletion of CD4+ T helper cells in later stages of human immunodeficiency virus (HIV) infection, evidence has been provided for a specific unresponsiveness to triggering either by specific antigen in the context of autologous major histocompatibility molecules (self + X) or anti-CD3 monoclonal antibodies (MAb) in both CD4 and CD8 cells from asymptomatic HIV-infected individuals. In the present study we analyzed this unresponsiveness using mitogenic antibodies to distinct T cell membrane receptors. T cells from HIV-infected men who had normal numbers of CD4+ T cells responded poorly to activation signals via the CD3 membrane antigen in both accessory cell-dependent as well as accessory cell-independent culture systems. A similar low response was observed in an anti-CD2-driven system. In contrast, proliferation induced by anti-CD3, anti-CD2, or the phorbol ester Phorbol myristate acetate could be normally enhanced by anti-CD28 MAb. We demonstrated that this unresponsiveness is not due to a failure to induce early events required for activation, such as increased intracellular concentration of free calcium and activation of protein kinase C, but is caused by an imbalance between naive and memory T cells. In HIV-infected asymptomatic men, CD29+ memory T cells are selectively depleted which results in a poor responsiveness to self + X. These findings provide new insights that may have implications for our understanding of the immunopathogenesis of AIDS.

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.

Possible role of natural cytotoxic activity in the pathogenesis of AIDS

In an attempt to assess the role of immune cytotoxic activity in the sequence of events leading to the acquired immunodeficiency syndrome (AIDS), natural cytotoxic activity was studied in 17 asymptomatic homosexual males, seropositive for anti-human immunodeficiency virus (HIV) antibodies, as compared to 16 of their seronegative counterparts and to 14 control healthy heterosexual individuals. Cell (contact)-mediated cytotoxicity (CMC) as well as cytotoxin (CTX) production by lipopolysaccharide (LPS)-stimulated, phytohemagglutinin (PHA)-stimulated, HeLa tumor cell-stimulated, and unstimulated peripheral blood mononuclear cells (PBMC) were determined using HeLa cell monolayer cultures, sensitized with cycloheximide, as targets. The CMC was markedly enhanced in the seropositive group (28 +/- 21 (mean +/- SD) lytic units/10(6) PBMC) as compared to the seronegative group (17 +/- 7; P less than 0.005) and to the heterosexual group (13 +/- 6; P less than 0.05). Likewise, CTX production by unstimulated PBMC from seropositive homosexuals (19 +/- 26 units/ml) was higher than that observed in the other groups (both 4 +/- 4 units/ml; P less than 0.05). CTX production by PHA-stimulated, LPS-stimulated, and HeLa cell-stimulated PBMC was significantly enhanced in both the seropositive and seronegative groups in comparison to the normal heterosexual controls. These results suggest that increased cytotoxic activity may be present in homosexuals prior to their exposure to HIV, and may be further enhanced after HIV infection.

Immune impairments and antibodies to HTLVIII/LAV in asymptomatic male homosexuals in Israel: relevance to the risk of acquired immune deficiency syndrome (AIDS)

We have studied 288 Israeli asymptomatic male homosexuals (MHS) to determine the prevalence of antibodies to HTLVI and HTLVIII and their correlation with impairments of the immune system and serum interferon (IFN). Seropositivity for HTLVI, HTLVIII, or both was found in 1.4, 8.3, and 0%, respectively. Significant decreases in the total peripheral T cells, TH cells, and TH/TS ratio as well as elevated alpha IFN serum levels were found in the MHS group in comparison with normal controls. Although no difference in the prevalence of either immune derangements or elevated serum IFN was observed between HTLVIII/LAV-seropositive and HTLVIII/LAV-seronegative MHS, the decreases in total T cells, TH cells, and TH/TS ratios were significantly greater in the seropositive MHS. These results indicate that (a) immune impairments and IFN system activation occur commonly in homosexuals, precede their exposure to HTLVIII/LAV, and probably reflect this group's increased risk for AIDS and (b) HTLVIII/LAV infection of MHS aggravates further their preexisting immune impairments.

Lymphoblastoid interferon therapy of chronic HBV infection. A comparison of 12 vs. 24 weeks of thrice weekly treatment

This study set out to examine the relative effectiveness and tolerability of 12- versus 24-week courses of thrice weekly intramuscular lymphoblastoid interferon in the treatment of hepatitis B 'e' antigen (HBeAg)-positive chronic hepatitis B virus (HBV) infection, and to identify pretreatment factors predicting the outcome of therapy. Twenty patients were randomised to each treatment group. Treatment was associated with clearance of HBeAg and HBV-DNA in 59% of the 32 male patients, whereas none of the eight women responded (48% overall response rate). This response rate in males is at least three times the recorded spontaneous seroconversion rates in this population. Most of the women (5/8) were of Oriental origin and had minimal disease, factors that may have influenced response. The longer course was poorly tolerated and was therefore no more effective: eight of 20 patients withdrew because of side-effects. Variables associated with response included high AST (aspartate transaminase), short duration of disease and previous history of acute hepatitis. A response to antiviral therapy was accompanied by clinical and biochemical evidence of improvement in liver disease.

Characteristics of the specific cell-mediated immune response in human immunodeficiency virus infection

The human immunodeficiency virus (HIV)-specific lymphocyte proliferation response was determined for 40 persons at different stages of HIV infection. The specific response to purified HIV virion antigens from strain HTLV-IIIB was poor, occurred in only 9 of the 40 subjects, was not improved with the addition of interleukin-2, and was more frequent in symptom-free individuals (46%) than in patients with lymphadenopathy syndrome (10%). Reactivity to subcomponent p24 was better than that to whole HIV; reactivity was present in five of six infected persons and increased with the addition of exogenous interleukin-2. Reactivities to subcomponents (g)p41 and gp120 were also measured. This is the first evidence of a specific cell-mediated immune response to HIV antigen in HIV-infected persons. Monkeys immunized with purified HIV or with purified p24 displayed cellular immunoreactivity both to whole HIV and to subcomponents. In contrast to the poor reactivity to HIV antigen, the lymphocytes of the patients had good specific cell proliferation responses to cytomegalovirus and herpes simplex virus challenge and a normal response to the addition of phytohemagglutinin. The results suggest a functional defect in peripheral lymphocytes of some HIV-infected individuals on the basis of their response to whole HIV antigen and a better response to gag protein.

Therapy of acquired immune deficiency syndrome with recombinant interleukin-2

Recombinant human interleukin-2 (rIL-2) was administered to 87 patients with the acquired immune deficiency syndrome (AIDS) to test the hypothesis that this lymphokine would correct the underlying qualitative and quantitative deficiency in cellular immunity. Patients were divided into two groups by the presence or absence of Kaposi's sarcoma and subjects within each of these groups received intravenous rIL-2 three times weekly for eight weeks. Subjects received one of several doses which ranged from 1,000 to 2,000,000 units per square meter body surface area. Toxicity at high doses consisted of flu-like symptoms and hypotension at highest doses. Partial objective tumor regression was observed in three patients with Kaposi's sarcoma. Seventeen patients had progression of disease (new opportunistic infection or increase in Kaposi's sarcoma) during therapy. No improvement in immunologic status was observed. This study does not suggest a role for single-agent rIL-2 therapy of established AIDS but its use in less symptomatic persons or in conjunction with antiretroviral agents such as azidothymidine should be investigated.

Immunoreconstitution of T-cell impairments in asymptomatic male homosexuals by thymic humoral factor (THF)

The feasibility of using Thymic Humoral Factor (THF) for immunomodulation in asymptomatic male homosexuals was evaluated in a study on fifteen subjects with T-cell impairments, selected on the basis of a 2SD reduction in T helper/inducer (T4+) cells and one additional lymphocytic defect. Following two biweekly courses of treatment, mean relative increments of T4+ (P less than 0.002), T3+ (P less than 0.02) and total lymphocyte (P less than 0.05) populations of the group receiving THF (n = 7) were significantly increased when compared to the placebo group (n = 8). In addition, a transient increase in T4+ lymphocytes was observed after the first course in the two individuals of the THF-treated group who were seropositive for HTLV-III/LAV but not in those who were seronegative. No difference was found between the groups in fluctuations of serum interferon (IFN) or proliferation of peripheral mononuclear cells to mitogens. The results of this limited trial demonstrate that THF is capable of correcting T-cell impairments that may predispose asymptomatic homosexuals to infection by HTLV-III, without affecting IFN production. These findings suggest that future strategies for AIDS prevention in high-risk groups should include institution of large controlled trials in immunodeficient, asymptomatic, HTLV-III/LAV-seronegative male homosexuals to study the potential of selective immunoreconstitution as a preventive measure against HTLV-III/LAV infection.

Cytotoxic capabilities of lymphocytes from patients with the acquired immunodeficiency syndrome

Lymphocytes from 16 AIDS patients were tested in the cell-mediated lympholysis assay (CML). The ability to produce alloreactive cytotoxic lymphocytes in vitro was found to be substantially reduced when compared with concomitantly investigated normal controls. Addition of interleukin 2 (IL-2) to the inducer cultures increased the cytotoxic activity, but not to normal levels. The CML response did not correlate with the relative or absolute number of Leu 3+ cells or the proliferation in effector suspensions. The ability to produce cytotoxic cells in CML, and the degree of potentiation by IL-2, was positively correlated with the absolute number of Leu 2+ cells in peripheral blood of the patients, which was below normal in 56% of the patients. It is suggested that the low CML in AIDS patients is primarily caused by defective T-cell help. In addition patients with decreased absolute numbers of Leu 2+ cells may have a reduced number of CTL precursors. The natural killer (NK) activity of AIDS lymphocytes was reduced, but could be improved by incubation with IL-2 in vitro. The mononuclear cells from the patients showed a decreased ability to respond and to stimulate in the mixed lymphocyte culture. In one of the AIDS patients, the CML was found to induce autoreactivity in vitro.

Prospective study of cytotoxic T lymphocyte responses to influenza and antibodies to human T lymphotropic virus-III in homosexual men. Selective loss of an influenza-specific, human leukocyte antigen-restricted cytotoxic T lymphocyte response in human T lymphotropic virus-III positive individuals with symptoms of acquired immunodeficiency syndrome and in a patient with acquired immunodeficiency syndrome

Peripheral blood leukocytes (PBL) from 18 homosexual men who did not have acquired immunodeficiency syndrome (AIDS) and from 9 heterosexual men were repetitively tested for their ability to generate HLA self-restricted cytotoxic T lymphocyte responses to influenza virus (flu-self) over a 2-yr period. The sera of the same donors were tested for antibodies to human T lymphotropic virus-III (HTLV-III). Six of the homosexual and none of the heterosexual donors consistently generated weak cytotoxic T lymphocyte responses to flu-self. Seven of the homosexual and none of the heterosexual donors were seropositive for antibodies to HTLV-III. No obvious correlation was detected between weak flu-self cytotoxic T lymphocyte responses and antibodies to HTLV-III. However, one homosexual donor generated no detectable cytotoxic T lymphocyte activity to flu-self, although he was a strong responder to HLA-alloantigens. This donor had an OKT4:OKT8 ratio of 0.4 and was seropositive for HTLV-III antigens; HTLV-III virus was identified in his PBL; and he developed AIDS during the course of this study. A second donor with lymphadenopathy and who was seropositive for HTLV-III antigens exhibited marginal cytotoxic T lymphocyte activity to flu-self which he subsequently lost. PBL from two patients, one with Kaposi's sarcoma and one with generalized lymphadenopathy, were also tested for cytotoxic T lymphocyte responses to flu-self and to alloantigens. Both donors failed to generate cytotoxic T lymphocyte to flu-self, but generated strong cytotoxic T lymphocyte responses to alloantigens. The selective loss of an HLA-restricted cytotoxic T lymphocyte response without loss of HLA alloantigenic cytotoxic T lymphocyte activity may be an important functional immunologic characteristic in the development of AIDS.

Antibodies to HTLV-III and the lymphadenopathy syndrome in multitransfused beta-thalassemia patients

Antibodies to HTLV-III have been investigated in 118 multitransfused beta-thalassemia patients. Thirteen patients (11.01%) were found to be positive; 3 of these 13 showed clinical and immunological signs of the lymphadenopathy syndrome. A retrospective study carried out on 65 sera has shown that at least 6 patients were negative 3 years before the present investigation. This is the first extensive study on HTLV-III infection in multitransfused beta-thalassemics. It suggests that these patients are at risk for the acquired immune deficiency syndrome and related diseases.