Multiple monoclonal B cell expansions and c-myc oncogene rearrangements in acquired immune deficiency syndrome-related lymphoproliferative disorders. Implications for lymphomagenesis.

AIDS (acquired immune deficiency syndrome) and ARC (AIDS-related complex) are associated with a spectrum of lymphoproliferative disorders ranging from lymphadenopathy syndrome (LAS), an apparently benign polyclonal lymphoid hyperplasia, to B cell non-Hodgkin's lymphoma (B-NHL), i.e., malignant, presumably monoclonal B cell proliferations. To gain insight into the process of lymphomagenesis in AIDS and to investigate a possible pathogenetic relationship between LAS and NHL, we investigated the clonality of the B or T lymphoid populations by Ig or T beta gene rearrangement analysis, the presence of rearrangements involving the c-myc oncogene locus, and the presence of human immunodeficiency virus (HIV) sequences in both LAS and B-NHL biopsies. Our data indicate that multiple clonal B cell expansions are present in a significant percentage of LAS (approximately 20%) and B-NHL (60%) biopsies. c-myc rearrangements/translocations are detectable in 9 of our 10 NHLs, but not in any of the LAS cases. However, only one of the B cell clones, identified by Ig gene rearrangements carries a c-myc gene rearrangement, suggesting that only one clone carries the genetic abnormality associated with malignant B cell lymphoma. Furthermore, the frequency of detection of c-myc rearrangements in AIDS-associated NHLs of both Burkitt and non-Burkitt type suggest that the biological alterations present in AIDS favor the development of lymphomas carrying activated c-myc oncogenes. Finally, our data show that HIV DNA sequences are not detectable in LAS nor in NHL B cell clones, suggesting that HIV does not play a direct role in NHL development. Taken together, these observations suggest a model of multistep lymphomagenesis in AIDS in which LAS would represent a predisposing condition to NHL. Immunosuppression and EBV infection present in LAS can favor the expansion of B cell clones, which in turn may increase the probability of occurrence of c-myc rearrangements leading to malignant transformation.

Expression of Ley antigen in human immunodeficiency virus-infected human T cell lines and in peripheral lymphocytes of patients with acquired immune deficiency syndrome (AIDS) and AIDS-related complex (ARC).

Ley determinant (Fuc alpha 1----2Gal beta 1----4[Fuc alpha 1----3]GlcNAc beta 1----R) defined by mAb BM-1 is highly expressed in human immunodeficiency virus (HIV)-infected T cell lines and in CD3+ peripheral mature T cells of patients with acquired immune deficiency syndrome (AIDS) or with AIDS-related complex (ARC). Ley expression increased greatly in the CD3+ population in the advanced stage of AIDS when the CD4+ population decreased greatly. Six other carbohydrate antigens tested by their respective mAbs were not detected in these same cells. None of the carbohydrate antigens tested by the seven mAbs used in this study were found in noninfected T cell lines and in normal peripheral blood lymphocytes.

Characterization and clinical association of antibody inhibitory to HIV reverse transcriptase activity.

Reverse transcriptase activity of the human immunodeficiency virus (HIV) was blocked in vitro by immunoglobulin G (IgG) derived from certain individuals infected with this retrovirus. A heterogeneous immune response for inhibition of enzyme function was noted. Catalytic activity was depressed by 50% or more with the use of 10 micrograms of IgG from 11 of 16 HIV-seropositive asymptomatic carriers, but from 0 of 8 seronegative controls and 2 of 12 patients with acquired immune deficiency syndrome (AIDS) or the AIDS-related complex (ARC). The inhibitor was confined to the F(ab')2 fragment. It was not directed against the poly(rA) X oligo(dT) template, nor against major envelope or structural viral antigens, and did not cross-react with bacterial, avian, or other mammalian DNA polymerases. It did not correlate with recognition of polymerase antigens by radioimmunoprecipitation. Loss of this inhibitor may be associated with development of clinical disease. Ten asymptomatic HIV-seropositive carriers with high titers of IgG antibodies to reverse transcriptase were followed for a mean of 3 years. All of four lost inhibitory capability prior to development of AIDS or ARC, while titers persist in the six who remain clinically healthy.

In vivo activity against HIV and favorable toxicity profile of 2',3'-dideoxyinosine.

The purine analog 2',3'-dideoxyinosine (ddI), which has anti-retroviral activity in vitro was administered for up to 42 weeks to 26 patients with acquired immunodeficiency syndrome (AIDS) or severe AIDS-related complex (ARC). Ten of these individuals were AZT-intolerant. Eight dose regimens were studied. The drug was orally bioavailable and penetrated into the cerebrospinal fluid (CSF). Comparatively little evidence of an effect against human immunodeficiency virus (HIV) was seen at the lowest four doses. However, patients in the four highest dose groups (ddI at 1.6 milligrams per kilogram intravenously and then greater than or equal to 3.2 milligrams per kilogram orally at least every 12 hours or higher) had increases in their circulating CD4+ T cells (P less than 0.0005), increased CD4/CD8 T cell ratios (P less than 0.01), and, where evaluable, more than an 80% decrease in serum HIV p24 antigen (P less than 0.05). The patients also had evidence of improved immunologic function, had reduced viremic symptomatology, and gained a mean of 1.6 kilogram with these comparatively infrequent dosing schedules (every 8 or 12 hours). The most notable adverse effects directly attributable to ddI administration at the doses used in this study included increases in serum uric acid (due to hypoxanthine release) and mild headaches and insomnia. These results suggest that serious short-term toxicity at therapeutic doses is not an inherent feature in the profile of agents with clinical anti-HIV activity. Further controlled studies to define the safety and efficacy of this agent may be worth considering.

Altered erythrocyte C3b receptor expression, immune complexes, and complement activation in homosexual men in varying risk groups for acquired immune deficiency syndrome.

We studied levels of erythrocyte C3b receptors (E-CR1) and correlated them to the level of circulating immune complexes (CIC) and complement activation in patients with or at risk for acquired immunodeficiency syndrome (AIDS). A significant reduction was found in patients with AIDS (185 +/- 93 CR1/cell), AIDS-related complex, and generalized lymphadenopathy, whereas healthy male homosexuals or normal controls had 434 +/- 193 and 509 +/- 140 CR1/cell, respectively (P less than 0.001). Family studies indicate that this defect is acquired. Reduction in E-CR1 was associated with increased levels of CIC when assayed by binding to Raji cells, but not when tested by C1q binding. Complement activation was assessed by levels of C3bi/C3d-g in plasma, measured with a monoclonal antibody specific for a neoantigen in C3d. AIDS patients had increased C3 activation (2.68 +/- 1.67%) when compared with normal controls (0.9 +/- 0.22%) (P less than 0.01). The decreased E-CR1, the presence of CIC, and C3 activation suggest that complement activation by immune complexes may play a role in the clinical expression of the disease.

CD8+ cell anti-HIV activity correlates with the clinical state of the infected individual.

The extent of antiviral activity exhibited in vitro by CD8+lymphocytes from individuals infected by HIV-1 correlates significantly with their clinical status. CD8+ lymphocytes from asymptomatic subjects were found to inhibit HIV-1 replication by 90% or greater at effector/target (E/T) ratios ranging from as low as 0.05 to 0.25. CD8+ cells from 17 of 19 (89%) of these subjects suppressed replication at an E/T ratio of 0.10 or less. CD8+ lymphocytes from symptomatic patients (non-AIDS) inhibited HIV-1 replication at E/T ratios ranging from 0.05 to 1.0, and CD8+ cells from 8 of 13 (62%) required ratios greater than 0.10. As a group, patients with AIDS exhibited the lowest degree of anti-HIV activity with their CD8+ lymphocytes. The effective range of E/T ratios from AIDS patients was 0.10-2.0, and 9 of 10 (90%) required E/T ratios greater than 0.25. This anti-HIV activity exhibited by CD8+ cells also correlated significantly with the subject's peripheral blood CD4+ cell count. The relative extent of CD8+ cell anti-HIV-1 activity was not found dependent on variations in the CD4+ target cells and viruses used. These findings suggest that the decreased CD8+ cell antiviral activity is related to progression to disease in HIV-infected individuals.

Lymphocyte proliferative responses to human immunodeficiency virus antigens in vitro.

All HIV seronegative (HIV Ab-) and most HIV seropositive (HIV Ab+) individuals' lymphocytes failed to proliferate in primary cultures in response to purified HIV or to recombinant envelope and core antigens of HIV, even in the presence of recombinant interleukin 2 (rIL-2). Most HIV Ab- and HIV Ab+ individuals' lymphocytes, however, could proliferate or be induced by rIL-2 to proliferate in response to lysates of Escherichia coli or Saccharomyces cerevisiae. These findings indicate selective defects in lymphocyte proliferative responses to HIV antigens before the development of AIDS in which lymphocytes are unable to proliferate in response to any antigens. These defects in cell-mediated immune responses to HIV antigens are likely to play an important role in the pathobiology of HIV infections. Although intact HIV or glycosylated gp120 envelope protein of HIV are involved in these defects, a non-glycosylated recombinant form of the HIV gp120 envelope (ENV2-3) and p25 core proteins did not inhibit antigen- or mitogen-driven lymphocyte proliferation.

Tissue infiltration in a CD8 lymphocytosis syndrome associated with human immunodeficiency virus-1 infection has the phenotypic appearance of an antigenically driven response.

HIV-1 infection may initiate to an HLA-associated response designated diffuse infiltrative lymphocytosis syndrome, characterized by increased numbers of circulating CD8 T cells that infiltrate salivary glands, lungs, gastrointestinal tract, and kidneys. Since this response could either be an antigenically driven process induced by HIV-1 or a lymphoproliferation of cells with neoplastic or unusual features, we sought to define the phenotype of the cellular populations, the nature of tissue derangement, and the tissue localization of virus in diffuse infiltrative lymphocytosis syndrome. Circulating CD8 T cells were greatly increased while CD4 T cell numbers remained in the range found in asymptomatic seropositive persons. The majority of CD8 and CD4 T cells in both blood and tissues had the memory phenotype of CD29+ (beta 1 integrin) and CD11a+/CD18 (beta 2 integrin) expression, but lacked markers of recent activation. A proportion of the circulating CD8 T cells also expressed CD57 (Leu 7) but not other markers of natural killer cells. HIV-encoded proteins were identified in tissue macrophages located in periacinar areas of the salivary glands. CD54 (intercellular adhesion molecule-1), a ligand for the CD11a integrin, was strongly expressed on postcapillary venule endothelium within lymphoid foci, and HLA-DR molecules were found on limited regions of ductular epithelium adjacent to lymphoid aggregates. These findings suggest that (a) the visceral lymphocytic infiltration in diffuse infiltrative lymphocytosis syndrome is an antigen-driven, and MHC-determined, host immune response to an element associated with HIV-1 infection, and (b) that the specific adhesive molecule interactions mediating the cellular influx, as well as the subsequent tissue damage, reflect altered patterns of gene expression in tissues undergoing an immune response.

When to Monitor CD4 Cell Count and HIV RNA to Reduce Mortality and AIDS-Defining Illness in Virologically Suppressed HIV-Positive Persons on Antiretroviral Therapy in High-Income Countries: A Prospective Observational Study.

OBJECTIVE: To illustrate an approach to compare CD4 cell count and HIV-RNA monitoring strategies in HIV-positive individuals on antiretroviral therapy (ART). DESIGN: Prospective studies of HIV-positive individuals in Europe and the USA in the HIV-CAUSAL Collaboration and The Center for AIDS Research Network of Integrated Clinical Systems. METHODS: Antiretroviral-naive individuals who initiated ART and became virologically suppressed within 12 months were followed from the date of suppression. We compared 3 CD4 cell count and HIV-RNA monitoring strategies: once every (1) 3 ± 1 months, (2) 6 ± 1 months, and (3) 9-12 ± 1 months. We used inverse-probability weighted models to compare these strategies with respect to clinical, immunologic, and virologic outcomes. RESULTS: In 39,029 eligible individuals, there were 265 deaths and 690 AIDS-defining illnesses or deaths. Compared with the 3-month strategy, the mortality hazard ratios (95% CIs) were 0.86 (0.42 to 1.78) for the 6 months and 0.82 (0.46 to 1.47) for the 9-12 month strategy. The respective 18-month risk ratios (95% CIs) of virologic failure (RNA >200) were 0.74 (0.46 to 1.19) and 2.35 (1.56 to 3.54) and 18-month mean CD4 differences (95% CIs) were -5.3 (-18.6 to 7.9) and -31.7 (-52.0 to -11.3). The estimates for the 2-year risk of AIDS-defining illness or death were similar across strategies. CONCLUSIONS: Our findings suggest that monitoring frequency of virologically suppressed individuals can be decreased from every 3 months to every 6, 9, or 12 months with respect to clinical outcomes. Because effects of different monitoring strategies could take years to materialize, longer follow-up is needed to fully evaluate this question.

Comparison of methods for assessing chemotaxis of monocytes and polymorphonuclear leukocytes isolated from patients with AIDS or AIDS-related conditions.

We evaluated the ability of normal human peripheral blood monocytes and polymorphonuclear leucocytes (PMNL) isolated from patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related conditions (ARC) to migrate toward a chemoattractant. Migration in blind-well chambers was compared to that under agarose. Chemotaxis results obtained from both assays for PMNL were similar, however there was a difference in the results for monocyte chemotaxis. PMNL isolated from patients with AIDS, but not ARC, exhibited decreased spontaneous and directed chemotaxis when assessed in blind-well chambers and under agarose. Spontaneous and directed chemotaxis in blind-well chambers of AIDS patients' monocytes was normal. Directed migration of monocytes from ARC patients was greater than that of control, but spontaneous migration was comparable. Under agarose, spontaneous migration was depressed in monocytes of AIDS patients, while migration toward the attractant was depressed in those of ARC patients.

Sicca complex and infection with human immunodeficiency virus.

Five male patients with the persistent generalized lymphadenopathy syndrome also had a sicca complex. Salivary gland biopsy specimens showed diffuse lymphocytic infiltration of the glandular parenchyma. Serum autoantibodies and rheumatoid factor were not detected. All patients had IgG antibodies to human immunodeficiency virus and IgG to the viral capsid antigen of Epstein-Barr virus. These five patients had benign lymphocytic infiltrates in other organs (lung, liver, and kidneys). Sicca complex may be one of the various manifestations of the lymphoid hyperplasia noted in human immunodeficiency virus-infected patients. In these patients, the sicca complex showed specific features related to male predominance, lack of serum autoantibodies, and peripheral-blood T-lymphocyte subset distribution.

Presence and prognostic significance of antilymphocyte antibodies in symptomatic and asymptomatic human immunodeficiency virus infection.

The presence of antilymphocyte antibody (ALA) in patients with the acquired immunodeficiency syndrome (AIDS), identified in a previous study, was confirmed by testing a population of 200 patients with AIDS. Of these, 88% had significant levels of ALA vs only 8% of a control group of patients with non-AIDS-related diseases. In a prospective study, the levels of ALA were determined in 61 patients with AIDS-related complex who were followed up for 18 to 30 months. During this interval, 31 (67%) of 46 patients with significant elevation of ALA levels developed AIDS, while none of 15 patients without elevation of ALA levels progressed to AIDS. In a group of 85 apparently healthy homosexual men, also followed up for 18 to 30 months, a significant number of those with high levels of ALA developed clinically apparent disease, while those with low levels did not. These results show that the amount of ALA correlates with the present clinical status as well as the future risk of developing immune deficiency.

T4+ cell production of interferon gamma and the clinical spectrum of patients at risk for and with acquired immunodeficiency syndrome.

To fully characterize the relationship between the clinical manifestations of human immunodeficiency virus infection and T4+ cell defects, we determined T4+ cell number and interferon gamma (IFN-gamma) production in 238 patients. For asymptomatic homosexuals, patients with acquired immunodeficiency syndrome (AIDS)-related complex (ARC), and patients with fully established AIDS, clinical status correlated linearly with both T4+ cell number and T4+ cell-derived (antigen-stimulated) IFN-gamma secretion. For asymptomatic homosexuals, abnormalities in T4+ cell number and IFN-gamma generation were similar irrespective of human immunodeficiency virus seropositivity. For patients with ARC, those with lymphadenopathy (LA) alone or LA plus zoster or thrombocytopenia displayed T4+ cell defects similar to those observed in asymptomatic homosexuals. Patients with ARC with LA plus constitutional symptoms and/or oral thrush, however, had fewer T4+ cells, were strikingly more deficient in IFN-gamma production, and closely resembled those with AIDS. Among patients with AIDS, certain individuals with Kaposi's sarcoma (KS) alone were sufficiently less cytopenic and less immunodeficient than patients with opportunistic infections (Ols) to suggest that the immune impairment that predisposes to KS may differ. At the time patients with KS developed Ols, however, T4+ cell number and IFN-gamma-generating capacity had declined to the remarkably low levels observed in virtually all patients with Ols alone.

Effect of zidovudine on serum human immunodeficiency virus core antigen levels. Results from a placebo-controlled trial.

We assessed the effect of antiviral therapy on serum human immunodeficiency virus core antigen (HIV-Ag) levels in patients enrolled in the phase II trial on zidovudine for acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. Human immunodeficiency virus core antigen was detected in 45% of subjects at entry (59% with AIDS and 37% of patients with AIDS-related complex). Median HIV-Ag levels in zidovudine-treated subjects fell from 111 pg/mL at entry to 46 pg/mL at four weeks, while levels in placebo recipients did not change significantly. Decline in HIV-Ag in zidovudine recipients was sustained through 16 weeks of treatment and was significantly different from the placebo group. Anti-p24 antibody levels did not change in either group. We conclude that in patients with HIV-antigenemia changes in HIV-Ag level are an important marker of anti-retroviral activity.

Anticardiolipin antibodies in acquired immunodeficiency syndrome.

We undertook a prospective study of IgG and IgM anticardiolipin antibodies (ACAs) to determine their clinical significance in patients with acquired immunodeficiency syndrome (AIDS). IgG ACAs were found in 24 (92.3%) of 26 patients with AIDS who were hospitalized for pulmonary complaints (group 1) and in 13 (93%) of 14 patients with AIDS-related complex (group 2). In addition, 17 (94%) of 18 patients with AIDS (group 3) who had coagulation tests and were studied retrospectively had IgG ACAs. The prevalence of IgG ACAs in these three groups was significantly higher than in healthy controls, but was comparable to that in 31 consecutive patients with systemic lupus erythematosus (67.7%). The mean titer of IgG ACAs in group 1 was higher than in groups 2 and 3 but was not different from that in the patients with systemic lupus erythematosus. The frequency and titer of IgM ACAs in group 1 (7.6%) or group 2 (14.3%) were not significantly different from those in normal controls (4.7%). In contrast, half of the patients in group 3 had low-titer IgM ACAs. The serum titer of IgG ACAs in patients with AIDS with thrombocytopenia was significantly higher than it was in those with normal platelet counts. There was no association between ACAs and Pneumocystis carinii pneumonia or other infections, cancer, thrombosis, positive VDRL test, or presence of the lupus anticoagulant. The prevalence and titer of IgG or IgM ACAs were not associated with abnormal results of any coagulation test. Although we found IgG ACAs to be associated with thrombocytopenia in AIDS, their presence does not carry exactly the same clinical significance as it does in systemic lupus erythematosus. The high prevalence of ACAs in AIDS, in AIDS-related complex, and in otherwise healthy contacts with antibodies to human immunodeficiency virus suggests that their occurrence may be related to the underlying human immunodeficiency virus infection.

The interferon-induced Mx-homologous protein in people with symptomatic HIV-1 infection.

Twenty-six people with symptomatic HIV-1 infection were screened for the presence of interferon (IFN) alpha and IFN alpha antibodies in their sera and the presence of the IFN-induced intracellular Mx-homologous protein in their peripheral blood leukocytes. Eleven people had measurable IFN alpha levels ranging from 1 to 40 IU/ml. None of the sera tested was positive for IFN alpha binding or IFN alpha neutralizing antibodies in the assays employed. Twenty-five of the 26 people had significant levels of the Mx-homologous protein in their peripheral mononuclear cells. The Mx concentrations varied from 0.3 to 6 U/ml in the people studied. IFN alpha-positive people had significantly higher levels of the Mx homolog than IFN alpha-negative people (P less than 0.03). Furthermore, the Mx homolog content in Walter-Reed class 2 people was significantly lower than in Walter-Reed class 5/6 people (P less than 0.01). Our results suggest that the IFN system is activated in more than 90% of the people with lymphadenopathy-associated syndrome, AIDS-related complex and AIDS. Since acid-labile IFN alpha can induce the Mx homolog in vitro endogenously produced IFN alpha seems likely to be responsible for the high Mx homolog levels detected.

Rheumatoid factors and circulating immune complexes in HIV-infected individuals.

We studied serological aspects of autoimmunity in patients with AIDS, AIDS-related complex (ARC) and in individuals at risk for AIDS. Immunoglobulin (Ig) M, IgG and IgA rheumatoid factors (RF) were quantified by enzyme-linked immunosorbent assay (ELISA), Ig by radial immunodiffusion, and circulating immune complexes (CIC) by the CIC-conglutinin and CIC-complement 1q (C1q) assays. Mean IgM RF levels were normal in AIDS patients, but those of ARC patients were higher and more frequent than the levels defined by agglutination methods. Similar observations were made for intravenous drug users (IVDU) and for both HIV-seropositive and HIV-seronegative homosexual men. Mean IgG RF levels were normal in AIDS and ARC patients but high in homosexual men and, to a lesser degree, in IVDU. IgA RF levels were high in many AIDS and ARC patients, in homosexual men, and in haemophiliac and control groups. The selective increase of the IgA isotype in AIDS was confirmed by the Ig results, which also showed an IgG increase in all groups. IgM were mainly high in people with ARC. CIC were detected in 68% of ARC patients by both methods, and in 55% of AIDS patients by CIC-Clq. A high incidence of positive samples in all at-risk populations, but particularly in seronegative individuals, was observed using CIC-conglutinin. CIC-C1q also revealed larger amounts of CIC in HIV-seronegative individuals, mainly in homosexual men. The study of these humoral aspects of autoimmunity provides useful information on the impairment of B-cells in patients with AIDS and ARC.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of mononuclear cells from HIV-infected patients to B-cell mitogens: correlation with immunological and clinical features of disease progression.

Proliferation of mononuclear cells from HIV-seropositive patients to B-cell mitogens was studied in the absence and presence of mixed lymphocyte culture supernatants (MLC-sup). The results show: (1) patients' responses to B-cell mitogens overlap with normal responses but are, on average, consistently lower than normal; (2) the addition of MLC-sup increases the proliferative responses to T-cell-independent mitogens, but does not bring patient's responses up to control levels; (3) HIV-positive patients in all clinical categories have decreased responses to B-cell mitogens. Although some patients with AIDS Centers for Disease Control (CDC) group IVC and IVD have the lowest responses, asymptomatic (CDC group II) and AIDS-related complex (ARC; CDC groups III/IVA and IVB) patients also show significant defects. (4) The same patients were recategorized using an immunological staging system. Those patients with more normal immunohematological parameters have significantly greater responses to mitogens compared with patients with more abnormal immunological parameters. The data suggest that immunological staging could provide more information than clinical classification with respect to the underlying immunopathogenic events occurring in HIV infection.

Restriction of sensitivity of HIV-1-antigen ELISA by serum anti-core antibodies.

Addition of varying concentrations of HIV-1-seropositive plasma to purified virus particles and soluble viral antigen preparation inhibited the detection of HIV-1-antigen by ELISA. The degree of inhibition on p24 antigen ELISA depended on the relative concentrations of viral antigen and anti-p24 antibodies in the mixtures. The relevance of these observations to clinical specimens was demonstrated when serial plasma samples from nine AIDS-related complex (ARC) patients in a clinical trial of foscarnet therapy were assayed for p24 antigen. Six (66.6%) out of nine patients were negative on screening. However, when their plasma was centrifuged through a sucrose solution, virus particles were pelleted that were depleted of anti-p24 and virus-specific p24 antigen was detected in resuspended pellets obtained from samples from all six patients. Eight serial samples collected from a male homosexual over 50 weeks following seroconversion were also subjected to the separation procedure. HIV-1-antigen was detected in all eight samples. In the light of these observations, the application of the separation technique in monitoring the efficacy of zidovudine or other anti-retroviral therapy should reveal more precise antigen levels in patients who otherwise appear to be antigen-negative in HIV-antigen assays. We propose that the natural history of HIV infections follows a pattern of chronic viral infection with continuous shedding of virus particles circulating as immune complexes.

Decline of anti-p24 antibody precedes antigenaemia as correlate of prognosis in HIV-1 infection.

A cohort of 84 homosexual men presenting with persistent generalized lymphadenopathy (PGL) was studied between March 1982 and March 1987. A progression rate to AIDS of 5% per year was seen in those who were infected with HIV. Certain clinical features and routine laboratory investigations were significantly associated with an increased risk of disease progression, but had only limited predictive value. Two hundred and fifty-two serial sera from 57 patients were analysed for the p24 antigen (Abbott), the principal core protein of HIV and antibody against p24 by direct enzyme-linked immunosorbent assay (ELISA). Patients who remained well retained a high titre of anti-p24 antibody compared with those who progressed to AIDS-related complex (ARC) or AIDS. HIV antigen was detectable in 40% of AIDS patients 2 years before diagnosis, but antigenaemia was preceded by loss of anti-p24 antibody by up to 18 months and preceded AIDS by up to 40 months. ARC patients tended to be negative when tested for both alpha-p24 antibody and antigen, suggesting a transitional state. Analysis of the humoral response against gag proteins appears to correlate closely with clinical status and may be an earlier and more consistent way of predicting disease progression than p24 antigenaemia, or clinical and routine laboratory investigations.