Immunology of human immunodeficiency virus infection and the acquired immunodeficiency syndrome. An update

Factors associated with atypical radiological findings of pulmonary tuberculosis

BACKGROUND

Unusual radiological images may delay diagnosis of pulmonary tuberculosis. This study aimed to analyze the risk factors for an atypical radiological image in patients with pulmonary tuberculosis.

METHODS

We retrospectively analyzed data from patients admitted to one hospital from January 2013 to December 2016 for sputum smear-positive lung tuberculosis who underwent chest computed tomography (CT) on admission. Patients whose sputum cultures were positive for general bacteria were excluded. Patient characteristics and laboratory data were compared between patients with cavity and those without and between patients with upper predominant lung involvement and those without.

RESULTS

This study included 94 (93%) of 101 patients who underwent chest CT. The non-cavity group was older, had a greater number of females, had a lower C-reactive protein (CRP) level, and had a lower glomerular filtration rate. Multivariate analysis showed that a low CRP level (OR 0.808; 95% CI 0.674-0.967; p = 0.020) significantly predicted non-cavity pulmonary tuberculosis. The non-upper predominant lung involvement group was older and had a greater number of females, poorer performance status, a higher CRP level, and a lower serum albumin level. A poor performance status (OR 2.155; 95% CI 1.257-3.693; p = 0.005) was found to significantly predict pulmonary tuberculosis with non-upper predominant lung distributions.

CONCLUSIONS

A low CRP level and poor performance status were associated with non-cavity and non-upper predominant lung distribution, respectively, in patients with pulmonary tuberculosis. Tuberculosis patients with these characteristics may present unusual chest images.

Identifying factors associated with changes in CD4(+) count in HIV-infected adults in Saskatoon, Saskatchewan

More than doubling the national mean, Saskatchewan has the highest incidence of HIV in Canada. The progression of HIV is characterized by the decline in CD4⁺ T cells over time and can lead to immunological AIDS. Clinicians in Saskatoon, Saskatchewan, have observed a more rapid progression to AIDS in the recent years. The goal of this retrospective longitudinal cohort study was to investigate the rate of CD4⁺ cell depletion, as well as to determine the effects of multiple clinical and social factors that may contribute to an accelerated progression of HIV to AIDS in this population.

OBJECTIVE:

To assess the impact of clinical and social factors unique to HIV-infected adults in Saskatoon, Saskatchewan, regarding the rate of CD4⁺ count change, and to identify factors associated with a risk of CD4⁺ count decline.

METHODS:

A retrospective longitudinal cohort study from medical chart reviews at two clinics was conducted in Saskatoon. Univariate and multivariate linear mixed effects models were used to assess the impact of selected factors on CD4⁺ count change.

RESULTS:

Four hundred eleven HIV-infected patients were identified from January 1, 2003 to November 30, 2011. Two hundred eighteen (53%) were male, mean (± SD) age was 35.6 ±10.1 years, 257 (70.8%) were First Nations or Métis, 312 (80.2%) were hepatitis C virus (HCV) coinfected and 300 (73.3%) had a history of injection drug use (IDU). In univariate models, age, ethnicity, HCV, IDU, antiretroviral therapy and social assistance were significant. Using ethnicity, HCV and IDU, three multivariate models (models 1, 2, 3) were built due to high correlation. First Nations or Métis ethnicity, HCV coinfection and a history of IDU were associated with significantly lower CD4⁺ counts in multivariate models. Older age and social assistance were associated with significantly lower CD4⁺ counts in models 1 and 3. Age was marginally significant in model 2 (P=0.055). Not prescribed antiretroviral therapy was associated with a significantly negative CD4⁺ count slope in all multivariate models.

CONCLUSION:

The unique epidemiology of this HIV-infected population may be contributing to CD4⁺ count change. Increased attention and resources focused on this high-risk population are needed to prevent disease progression and to improve overall health and quality of life.

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.

Generality of the final size formula for an epidemic of a newly invading infectious disease

The well-known formula for the final size of an epidemic was published by Kermack and McKendrick in 1927. Their analysis was based on a simple susceptible-infected-recovered (SIR) model that assumes exponentially distributed infectious periods. More recent analyses have established that the standard final size formula is valid regardless of the distribution of infectious periods, but that it fails to be correct in the presence of certain kinds of heterogeneous mixing (e.g., if there is a core group, as for sexually transmitted diseases). We review previous work and establish more general conditions under which Kermack and McKendrick's formula is valid. We show that the final size formula is unchanged if there is a latent stage, any number of distinct infectious stages and/or a stage during which infectives are isolated (the durations of each stage can be drawn from any integrable distribution). We also consider the possibility that the transmission rates of infectious individuals are arbitrarily distributed--allowing, in particular, for the existence of super-spreaders--and prove that this potential complexity has no impact on the final size formula. Finally, we show that the final size formula is unchanged even for a general class of spatial contact structures. We conclude that whenever a new respiratory pathogen emerges, an estimate of the expected magnitude of the epidemic can be made as soon the basic reproduction number R0 can be approximated, and this estimate is likely to be improved only by more accurate estimates of R0, not by knowledge of any other epidemiological details.

Neuropathology of human immunodeficiency virus 1 infection. Significance of studying in forensic autopsy cases at Dar es Salaam, Tanzania

OBJECTIVE

In sub-Saharan Africa, only a few studies of neurologic complications of human immunodeficiency virus 1 (HIV-1) infection have been done. The authors studied neuropathology of HIV-1 infection in Tanzania.

DESIGN

Forensic autopsy study at Dar es Salaam, Tanzania.

SETTING

A joint research project between Dar es Salaam, Tanzania, and Kumamoto, Japan.

PATIENTS

Thirty patients with risk factors for HIV-1 infection.

MAIN OUTCOME MEASURES

Human immunodeficiency virus 1 infection was evaluated by HIV-1 antibody test on postmortem serum samples. The brains of HIV-1-infected persons were studied histopathologically.

RESULTS

Infection with HIV-1 was identified on postmortem serum samples in 10 of 30 forensic autopsy cases. Neuropathologic changes of the brain were observed in 8 of the 10 HIV-1-infected persons; these changes consisted of lymphocytic meningitis, bacterial meningoencephalitis, cryptococcal meningoencephalitis, tuberculous meningitis with brain abscesses, and intracerebral hemorrhage.

CONCLUSIONS

Because none of the persons studied was suspected to have had brain diseases before autopsy, the results suggest that brain diseases of HIV-1-infected patients are likely to go unrecognized in Tanzania. In addition, the high incidence of neuropathologic findings in HIV-1-infected persons indicates that HIV-1-related brain diseases are common in Tanzania, as they are in developed countries. Further forensic autopsy study will determine the range and prevalence of brain complications and have immediate impact on the management of HIV-1-infected patients in Tanzania and other developing countries.

B7 cosignal potentiates apoptosis of uninfected CD4+ T lymphocytic cell lines primed by HIV envelope proteins

In lymphoid organs, follicular dendritic cells (FDCs), monocytes, and macrophages are targets for HIV infection and reservoirs for infectious virus. Strikingly, the apoptotic cells in these sites are essentially uninfected CD4+ T lymphocytes, but lie in close proximity to infected cells or FDCs carrying trapped HIV virions. To decipher this apoptotic pathway, we have established a two-step experimental system that reproduces in vitro the HIV envelope protein-mediated apoptosis restricted to uninfected CD4+ T lymphocytic cell lines. In this assay, uninfected CD4+ T cell targets undergo apoptosis following an initial priming step on HeLa cells expressing functional HIV envelope proteins at their plasma membrane and a second and necessary stimulation step via the CD3-TCR complex. The CD4+ T lymphocytic cells susceptible to apoptosis are, in contrast, resistant to cell fusion mediated by HIV envelope protein and express SDF-1. FDCs and macrophages are known to be high B7 expressors. Thus in lymph nodes, the cells that have trapped HIV particles in immune complexes at the plasma membrane present both HIV envelope proteins and B7.1 at their surface. We mimicked this situation in vitro by priming CD4+ T lymphocytes on cells expressing the costimulatory molecule B7 in addition to HIV envelope proteins, and show that it resulted in an acceleration and a twofold increase in apoptosis. Finally, we characterized two enzymes, PI3Kinase and PI-PLC, which are both downstream effectors of the CD4 (HIV envelope protein receptor) and CD28 (B7 receptor) activation pathways, and that participated in the early steps of priming for apoptosis.

A pooled analysis of CD4 response to zidovudine and zalcitabine treatment in patients with AIDS and AIDS-related complex

INTRODUCTION

This article reports a meta-analysis focused on the efficacy of zalcitabine and zidovudine alone or in combination as reported by three AIDS Clinical Trial Group trials. We analyzed the log CD4 count (LCD4) response to therapy up to 1 year after the beginning of therapy. One of the purposes of this article was to illustrate a meta-analysis method that permits pooling of original data from trials with different designs.

METHODS

To effectively eliminate obvious differences due to design, we first estimated complete (1 year) individual LCD4 versus time curves using a sophisticated smoothing technique. Then several summary descriptors were computed from the completed LCD4 curves. Those descriptors were corrected for baseline covariate differences, and the corrected values were then related to measures of drug exposure.

RESULTS

Significant baseline covariates were LCD4 baseline count and AIDS-related complex or AIDS diagnosis. The predictor, corrected for baseline covariates, that correlated best with drug exposure was intensity, the initial rate of rise of LCD4, estimated as the slope of LCD4 between pretreatment and peak LCD4.

CONCLUSION

Using intensity as a single response measure, we found weak evidence for synergism of zalcitabine and zidovudine: combination therapy increased response by 20% over that expected from a purely additive interaction.

Pediatric human immunodeficiency virus infection

In the past decade, an increase in pediatric human immunodeficiency virus (HIV) infection has had a substantial impact on childhood morbidity and mortality worldwide. The vertical transmission of HIV from mother to infant accounts for the vast majority of these cases. Identification of HIV-infected pregnant women needs to be impoved so that appropriate therapy can be initiated for both mothers and infants. While recent data demonstrate a dramatic decrease in HIV transmission from a subset of women treated with zidovudine during pregnancy, further efforts at reducing transmission are desperately needed. This review focuses on vertically transmitted HIV infection in children, its epidemiology, diagnostic criteria, natural history, and clinical manifestations including infectious and noninfectious complications. An overview of the complex medical management of these children ensues, including the use of antiretroviral therapy. Opportunistic infection prophylaxis is reviewed, along with the important role of other supportive therapies.

Antigen/antibody content of circulating immune complexes in HIV-infected patients

Dual infection with HIV and hepatitis B virus (HBV) is not an uncommon feature. Immunity impairment due to HIV infection can be the cause of a higher rate of HBV replication with less intensive liver damage and less effective immune response to HBV. Many HIV-infected patients have an elevated level of circulating immune complexes (CIC) in serum, throughout all stages of illness evolution. The aim of our study was to estimate p24 and HBsAg content of CIC in dually infected patients, and the prevalence of major classes of complexed antibodies (IgM and IgG). We examined 146 samples of sera from 105 HIV positive patients of the Institute for Infectious and Tropical Diseases during 1992 and 1993. On those sera we performed p24Ag and HbsAg detection, with and without prior dissociation of CIC, we determined serum level of CIC and immunoglobulin classes IgM and IgG level in sera and in polyethilenglycol (PEG) precipitates of sera. Acid dissociation of immune complexes revealed a high proportion of HIV antigen positive sera in all stages of HIV disease progression. HbsAg in serum of HIV positive patients was also found coupled in immune complexes much more frequently than in the HIV negative control group. In many instances both antigens were simultaneously found coupled in CIC. Immune complexes detected have been shown to contain both IgM and IgG immunoglobulins, while IgM antibodies were associated to immune complexes in higher proportion than IgG, compared to total serum immunoglobulins.

Maternal-fetal transmission of HIV-1 infection

Studies to examine the mechanisms responsible for perinatal HIV transmission and clinical trials to reduce this transmission are ongoing. A more complete understanding of the timing and modalities of vertical transmission will permit more precise targeting of future clinical trials. Perinatal transmission of HIV infection is most likely due to multiple factors. The degree of viral replication, neutralizing antibody and other maternal immune factors, genetic factors, and an intact placental barrier are most likely important and may be interrelated. Multiple different combination therapies may be necessary to interrupt maternal-fetal HIV transmission. Pregnancy is a well-defined and limited time period, and offers a model for HIV transmission where clinical, virological, and immunological factors can be evaluated in relation to the occurrence of HIV infection in the infant. The analysis of perinatal trials may provide insight into factors involved in protection and have implications. As HIV infection rates in the heterosexual populations of US inner cities and in impoverished areas of the third world continue to rise rapidly, strategies are needed urgently to curb the AIDS epidemic in children. Targeting the HIV-infected pregnant woman for therapies is one of the few hopes we have of preventing infection in children at risk of HIV infection. Without such therapeutic strategies, many of these at-risk infants are destined to acquire a chronic viral infection with significant morbidity and mortality.

Feline immunodeficiency virus infection. Clinicopathologic findings in 90 naturally occurring cases

In 90 cats with naturally occurring feline immunodeficiency virus (FIV) infection, the clinicopathologic changes seen at the time of first diagnosis of FIV infection included lymphopenia (29%), neutrophilia (27%), monocytosis (23%), anemia (18%), leukocytosis (13%), leukopenia (13%), neutropenia (11%), hyperproteinemia (38%), and hyperglobulinemia (25%). Forty-nine (54%) of the cats showed multiple hematologic abnormalities, and a further 24 (17%) had a single abnormality. The most consistent changes in serum protein electrophoretic patterns were increases in the concentrations of alpha 2 globulin and gammaglobulin subfractions. Although there is no established system for staging the degree of immunosuppression in cats infected with FIV, cytopenias appeared to be more common in cats with advanced clinical signs of disease.

HIV-Leishmania co-infections in Italy: serological data as an indication of the sequence of acquisition of the two infections

Twenty-two sera from visceral leishmaniasis (VL) patients with human immunodeficiency virus (HIV) infection (50% with the acquired immune deficiency syndrome) were examined for anti-Leishmania immunoglobulin G (IgG) antibodies and compared with 35 sera from VL patients without HIV (controls). Significant titres of specific IgG were found in 81.8% of co-infections. However, while control sera showed a restricted range of anti-Leishmania IgG titres, sera from co-infection cases displayed a considerable degree of variability, both quantitative and qualitative. They were clearly divided into 2 groups: one (18 sera) showing a continuous grading from nil to mid-concentrations of specific antibodies, the other (3 sera) showing titres 30-fold higher than this range. Taking into account the major immunological abnormalities involving humoral response described in HIV patient, the 2 groups may reflect a different sequence of acquisition of the 2 infective agents; the former representing VL acquired after HIV infection, and the latter representing the contrary situation.

IgM response to a human Pneumocystis carinii surface antigen in HIV-infected patients with pulmonary symptoms

We have developed an ELISA to detect IgM antibodies to a major human Pneumocystis carinii surface antigen (gp95), and investigated the IgM response in 128 HIV-infected patients who underwent bronchoscopy for evaluation of pulmonary symptoms. Only 5 (4%) patients had IgM antibodies to P. carinii gp95. Four of the 5 patients with IgM antibodies also had IgG antibodies to gp95 and microbiologically proven P. carinii pneumonia (PCP). In 76/128 patients for whom serial samples were available, changes in antibody response were determined. In 3 patients we demonstrated an increase in IgM antibody response to gp95. These patients also showed an increase in IgG antibodies to gp95 and had microbiologically proven PCP. Prior to the development of the IgM response, IgG antibodies to gp95 were detectable in all 3 patients. Thus, HIV-infected patients with PCP seldom produce IgM antibodies to the major human P. carinii surface antigen. The increase in IgM response during the course of PCP observed in 3 patients suggests either reinfection with a new strain, or antigenic drift of an already acquired strain of P. carinii.

The defect seen in the phosphatidylinositol hydrolysis pathway in HIV-infected lymphocytes and lymphoblastoid cells is due to inhibition of the inositol 1,4,5-trisphosphate 1,3,4,5-tetrakisphosphate 5-phosphomonoesterase

Lymphocytes infected in vivo with HIV or lymphoblastoid cells exposed in vitro to either HIV or its envelope glycoprotein (gp120) show a defect in inositol polyphosphate-mediated signal transduction together with an associated abnormality in intracellular calcium regulation. The defect in patients reverses after treatment with the anti-retroviral agent zidovudine (AZT). We present evidence that the defect is at the level of the Ins (1,3,4,5)P4 5-phosphomonoesterase (PME) in these cells and that, though elevation of the intracellular ATP level partially down-regulates the activity of this enzyme, such changes alone are unable to account for the complete inhibition seen in HIV-infected cells.

Implications of HIV-specific cytotoxic T lymphocytes in AIDS

The immune response to HIV in infected humans leads to the production of HIV-specific cytotoxic T lymphocytes (CTL) which circulate in high frequencies. The presence of these CTL and their eventual protective activities have been studied by various laboratories, and correlations have been made with certain immunopathological manifestations of HIV infections. It seems probable that HIV-immune CTL participate in the induction of certain disorders by initiating inflammatory reactions in the lungs, central nervous system, and lymph nodes. Various virus antigens recognized by HIV-immune CTL on the surface of the infected cell have been identified, and the molecular definition of the epitopes recognized is well under way. Likewise, numerous HLA transplantation antigens that regulate HIV antigen recognition by CTL have been identified. These data are discussed in view of the development of an eventual vaccine and of functional immunotherapies. They are compared with results obtained in animal experimental systems.

Autoantibodies to c-myc protein: elevated levels in patients with African Burkitt's lymphoma and normal Ghanians

Sera from U.S. patients with SLE, RA, and various malignancies, clinically normal individuals with sero-activity to HIV, AIDS, and from pregnant women were tested for the presence of anti-c-myc antibodies. In an ELISA using recombinant human c-myc protein as the antigen, no difference in mean antibody titer was generally detected in these sera when compared to normal controls. Only three malignancy sera (two myeloid leukemia and only one lymphoma) and two patients with AIDS-related lymphoma exhibited exceedingly higher levels of anti-c-myc antibody. However, significantly elevated anti-c-myc antibody levels were found among 20 patients with African Burkitt's lymphoma (Ghana) and 20 normal Ghanians, thus apparently reflecting an autoimmune phenomenon prevalent in the endemic region. These findings indicated that elevated levels of anti-c-myc antibodies are not a general characteristic of patients with diseases that have been associated with increased expression of c-myc.

Medical management of AIDS patients. Tuberculosis and nontuberculous mycobacterial disease

AIDS has been responsible for a significant increase in mycobacterial disease, which in this setting is often extrapulmonary. In contrast to HIV-associated Mycobacterium avium complex disease, HIV-associated tuberculosis is normally transmissible between humans by the aerosol route, occurs earlier than most AIDS-related infections, and is readily treatable and preventable with conventional drugs.

Dual tropism of HIV-1 IIIB for chimpanzee lymphocytes and monocytes

In humans, macrophages serve as a major reservoir of human immunodeficiency virus (HIV-1) in the infected host and may play a role in the pathogenesis of the disease. In HIV-1-infected chimpanzees, however, virus could not be recovered from cells of the monocyte/macrophage lineage, leaving the question of macrophage tropism of HIV-1 in this species unresolved. The data reported that HIV-1 IIIB shows dual tropism and is infectious for both chimpanzee monocytes and lymphocytes in vitro. Viral replication in chimpanzee monocytes was clearly demonstrated by infection of allogeneic phytohemagglutinin (PHA) blasts in vitro and by electron microscopy (EM). EM revealed HIV particles associated with 10-15% of the HIV-1 IIIB-infected chimpanzee monocytes. Viral particles budding from the monocyte surface in the typical crescent form were noted as well. This is in contrast to the human situation, where monocytotropic HIV strains preferentially bud into and accumulate in cytoplasmic vacuoles. These results indicate that both lymphocytes and cells of the monocyte/macrophage lineage replicate virus in the chimpanzee; the cell tropism of viral strains, however, is different in chimpanzees and humans.

Lymphocyte blastogenic responses in sickle cell disease

Cell mediated immunity (CMI) has not been extensively studied in sickle cell disease (SCD). In this study, an assessment of lymphocyte blastogenic responses was done in 62 SCD patients (62 steady state and 25 in crisis with or without documented infection), along with 30 normal controls in good health and 10 with various infections. The mitogen phytohemagglutinin (PHA) and two antigens (Candida albicans and Tetanus Toxoid) were used as stimuli. An evaluation of these results by stimulation index revealed 53/62 (86%) of SCD steady state patients, 30/30 (100%) of healthy controls and 7/10 (70%) of normal control patients with infection positively responded to all three stimuli. Conversely, only 5/25 (20%) of SCD crisis state patients had totally normal blastogenic responses. Analysis of the data from SCD crisis patients revealed 14/20 (70%) with abnormally depressed proliferation to PHA, 11/20 (55%) to Candida and 6/20 (30%) to Tetanus. When comparisons were made by mean counts per minute, the most striking finding was the PHA response in the SCD crisis state. In this group the mean counts per minute were significantly less than the three other groups by statistical analysis. This data suggests that the crisis state, especially when associated with infection, profoundly effects blastogenic responses to PHA and to a lesser degree in vitro antigenic stimulation. The normal group with infection showed similar diminished blastogenesis to antigen, but no effect on mitogen response.

A simulation model of AIDS in San Francisco: I. Model formulation and parameter estimation

A model is formulated for the spread of the human immunodeficiency virus (HIV) and the subsequent development of acquired immunodeficiency syndrome (AIDS) in the population of homosexual men in San Francisco. The dynamic simulation model includes sexually very active and active subpopulations, migration, and a staged progression of HIV-infected persons to AIDS and death. Numerous data sources are used to estimate parameter values in the model. In a companion paper, simulations using the model and parameter estimates are found that are consistent with HIV and AIDS incidence data.

Activation of human peripheral blood mononuclear cells by interleukin-2 and granulocyte-macrophage colony-stimulating factor to inhibit Cryptococcus neoformans

The abilities of selected cytokines to activate human peripheral blood mononuclear cells (PBMC) to inhibit and kill the opportunistic fungus Cryptococcus neoformans were studied. PBMC were cultured for 7 days in cell wells containing no cytokines, tumor necrosis factor (TNF), gamma interferon (IFN-gamma), 1,25-dihydroxycholecalciferol (vitamin D3), granulocyte-macrophage colony-stimulating factor (GM-CSF), or interleukin-2 (IL-2) and were then challenged for 24 h with a fixed number of CFU of C. neoformans. The number of CFU increased in wells containing no cytokines, TNF, IFN-gamma, or vitamin D3 and remained about the same in wells containing GM-CSF. In contrast, the number of CFU in wells containing IL-2-stimulated PBMC decreased, suggesting fungicidal activity. Optimal conditions for IL-2 stimulation included a minimum of 5 days of incubation of PBMC with IL-2, a concentration of 100 U of IL-2 per ml, and a high ratio of effectors to fungi. Separation of IL-2-stimulated PBMC based upon their adherence to plastic revealed that antifungal activity resided in the nonadherent fraction. These data demonstrate that IL-2 and GM-CSF are capable of stimulating PBMC-mediated antifungal activity and suggest that these cytokines may play physiological or pharmacological roles in host defenses against cryptococcosis.

Cellular and antibody responses directed against the HIV-1 principal neutralizing domain in HIV-1-infected children

The principal neutralizing domain (PND) for antibody response is located within the V3 variable region of gp120 and can also stimulate T-cell responses. In some adults infected with human immunodeficiency virus (HIV) an HIV-1-specific T-cell response can be detected by demonstrating in vitro proliferation to HIV-1 proteins and peptides. In other HIV-1 infected adults an HIV-1-specific T-cell response can involve interleukin 2 (IL-2) secretion in the absence of T-cell proliferation. To elucidate the T-cell responses to PND in children, we examined the proliferative and the IL-2 secretory responses of peripheral blood lymphocytes from 19 HIV-1-infected children toward a peptide which contained a highly conserved sequence of the principal neutralizing domain of HIVMN (PND-MN). Stimulation with PND-MN induced proliferation of lymphocytes from 2 of the children and IL-2 secretion by lymphocytes from 5 of the children. In a 3-month-old infant, the in vitro cellular response to the PND-MN indicated HIV-1 infection prior to the detection p24 antigen in her serum. Although antibodies directed against PND-MN were detected in all but one of the children examined, the presence of high-affinity/avidity antibodies to the PND-MN correlated with the presence of a cellular response to PND-MN. Thus, in HIV-1-infected children an HIV-1 specific T-cell response in the absence of a proliferative response can be assessed by determination of the IL-2 secretory response and correlates with the generation of high-affinity/avidity antibodies.

A computer simulation of the natural history of HIV infection: insights and implications

Computer simulation of the natural history of HIV infection shows that the progression from a silent infection to serious disease need not depend upon any particular biological event but only requires the passage of time. It likewise illustrates why modest efficacy from an antiretroviral agent can go a long way toward treating HIV infection, but a cure will be difficult to develop.

Prevalence of antibodies to human herpesviruses and hepatitis B virus in patients at different stages of human immunodeficiency virus (HIV) infection

The results of antibody assays for viruses of the herpes group (HSV, EBV, VZV and CMV) and for hepatitis B virus (HBV) were retrospectively evaluated in 439 HIV-seropositive patients classified into different stages of HIV infection. The prevalence of specific IgG, IgM and IgA antibodies in these groups was compared with that of a control group of HIV-negative unselected hospital patients. Antibodies to herpes viruses and HBV were more prevalent amongst HIV-seropositives, especially LAS and AIDS patients than in controls. However, marked differences were found only with CMV-IgG and anti-HBc-IgG, both with a comparatively low prevalence in HIV-negative persons (64.5% and 23.2%). Significantly more seropositives were found among asymptomatic HIV carriers (83.3% and 50%) and still more in patients with full-blown AIDS (95.4% and 82.5%). The increased frequency of CMV and HBV antibodies, already seen in asymptomatic HIV patients reflects their higher risk for sexually transmitted infections. Moreover, IgA antibodies to CMV were detected in 25.4% of LAS and 37.3% of AIDS patients, respectively, but only in 7.6% of the controls. Elevated CMV-IgA titres were found exclusively in HIV-infected persons. The differences in the antibody patterns found in this cross-sectional study may reflect the progression of the HIV disease. However, prospective follow-up studies are required to assess the value of these markers as indicators of prognosis in HIV-infected subjects.

Surgical pathology of the liver in HIV infection

In the 6-year period 1984-1989, 101 liver biopsies or 'needle necropsies' from human immunodeficiency virus positive patients were examined histologically. Of these, only nine showed no abnormality whatsoever. The commonest histological findings were either fatty change or changes related to co-existent chronic viral hepatitis. Granulomas were seen in 15 cases, four of which were positive for acid-fast bacilli. A range of organisms were recorded: cytomegalovirus (4); Histoplasma capsulatum (1); Pneumocystis carinii (2); Cryptococcus neoformans (1); and Leishmania donovani (1). There were two cases of non-Hodgkin's lymphoma, but no cases of Kaposi's sarcoma. Marked iron deposition, which correlated with multiple blood transfusions was seen in nine biopsies. We were unable to identify any histological feature in the liver as being specific for HIV infection. The high incidence of liver abnormalities reflects: (i) the coincident exposure to hepatotropic viruses; (ii) the presence of opportunistic infections and neoplasms, usually part of a disseminated multi-organ process arising in the setting of profound immune depression; (iii) iatrogenic causes, in particular iron overload related to multiple blood transfusions received for treatment of zidovudine-induced anaemia; and (iv) non-specific changes associated with chronic debilitating disease.

IgG subclass responses to human immunodeficiency virus-1 antigens: lack of IgG2 response to gp41 correlates with clinical manifestation of disease

To analyze differential antibody responsiveness of potential pathogenetic significance, sera from 66 patients with human immunodeficiency virus-1 (HIV-1) infections at various Walter Reed (WR) stages of the disease were analyzed to determine the subclass distribution of HIV antibodies. Although all IgG subclasses were involved in the HIV antibody response, the frequency was highest for IgG1 and the lowest for IgG4. When IgG subclass responses to different HIV antigens were compared qualitatively, IgG1 was the major subclass reactive with env, pol, and gag antigens; IgG2 and IgG3 were almost equally represented in response to gag gene products; and IgG4 showed minimal reactivity to p24 antigen in all HIV-infected patients regardless of their clinical presentation. In contrast, significantly lower levels of IgG2 anti-gp41 were observed in patients at WR 5 and 6 (5%) when compared to those at stage WR 1 and 2 (88%). The IgG2 response to a recombinant gp 120/41 antigen, however, remained unchanged, suggesting that the lack of IgG2 response may be associated with lack of responsiveness to the carbohydrate epitope on gp41. Indeed, parallel measurements of IgG antibody responses to group A carbohydrate were also lower in patients at WR 5 and 6 stages, without affecting antibody responses to polyribosyl ribitol phosphate and phosphocholine. As antibody responses to group A carbohydrate with its N-acetyl D-glucosamine (GlcNAc) determinant were lower at the WR 5 and 6 stage of HIV disease, GlcNAc may be one of the antigenic determinants on gp41 that plays a critical role in some of the pathologic events of HIV infection.

Differential staphylococcal protein A-induced enhancement of natural killer cell activity of lymphocytes from HIV-seropositive individuals

A decrease in Natural Killer (NK) cell activity is a common feature of the immune dysfunction found in patients with HIV-induced acquired immune deficiency syndrome (AIDS). We and others have shown earlier that staphylococcal protein A (SpA) preparations enhance NK cell activity against tumor targets. The present study was aimed at exploring whether the decreased NK activity of lymphocytes from HIV seropositive subjects could be modulated or restored in vitro by SpA. Two types of HIV-seropositive subjects were studied: hemophiliac and non-hemophiliac; matched controls were chosen among hospital staff and HIV-seronegative hemophiliac volunteers. In vitro proliferation and interleukin-2(IL-2)/interferon gamma (IFN gamma) release in response to mitogens were also studied. NK cell responses of peripheral blood lymphocytes (PBL) of HIV-seropositives were lower than those of seronegatives. However, exposure of PBL from HIV-seropositive individuals to SpA boosted their NK cell responses against NK-resistant target cells of tumor origin. The decrease in NK activity could not be attributed to the low number of NK cells, since no significant difference in NK cell number was observed between HIV-seropositive individuals and controls. Mitogen-induced blastogenic responses were present in all four groups, as was the mitogen-induced IFN gamma release. We conclude that impaired NK activity and its boosting against NK-resistant targets after SpA induction is an important characteristic of lymphocytes of HIV-seropositive individuals regardless of the disease state and that this NK defect may not be irreversible.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum non-organ specific autoantibodies in human immunodeficiency virus 1 infection

Serum samples from 66 seropositive subjects (56 with a history of intravenous drug abuse), including asymptomatic carriers and patients with persistent generalised lymphadenopathy (PGL), AIDS related complex (ARC), and AIDS, were tested by indirect immunofluorescence on rat tissue sections and HEp-2 cells for the presence of antibodies to nuclei, smooth muscle, intermediate filaments (anti-IMF) and microfilaments (anti-MF). Counterimmunoelectrophoresis was also used to detect antibodies to extractable nuclear antigens. Smooth muscle antibodies with the V pattern or antinuclear antibodies, mainly of the speckled type, or anti-IMF, occurred in 35 cases, being widely distributed in all groups. Such an autoantibody response resembles the "viral" autoimmunity described in various infectious diseases and in particular that of non-A, non-B post-transfusion hepatitis. Autoantibodies may be of some prognostic relevance, as the prevalence of smooth muscle antibodies V increased as the disease progressed (asymptomatic carriers 20%, those with PGL 29%, those with ARC 47%, and those with AIDS 63%. In the PGL group autoantibody positivity correlated with the presence of skin anergy. The fact that autoantibodies were more frequently detected in patients with circulating immune complexes suggests that these can contain autoantibodies and the corresponding autoantigens.

Spontaneous release of interferon as a predictor of clinical evolution in HIV-positive subjects

In order to establish a correlation with disease progression we prospectively evaluated ten clinical and immunologic parameters in 102 consecutive HIV-positive subjects. The eight immunologic variables were: in vitro spontaneous interferon release by peripheral blood monocytic cells, alpha- and gamma-interferon production induced by Newcastle Disease Virus and PHA, Multitest Mérieux score, PHA- and CON-A-induced lymphocyte transformation, absolute number of CD4+ cells and CD4/CD8 ratio, respectively. The two baseline clinical variables were risk factor and disease presentation. Generalized Wilcoxon analysis indicated a significant correlation of one clinical (disease presentation at entry) and three immunologic variables (spontaneous interferon release, CD4+ cell number, Multitest Mérieux) with disease progression. Baseline spontaneous release of alpha, acid-labile interferon showed the best correlation with disease progression, and appeared to be significantly associated with CD4+ cell loss. Spontaneous release of acid-labile alpha interferon by mononuclear cells in vitro could be highly predictive of disease evolution in HIV-Ab positive, AIDS-free subjects.

Hodgkin's disease after non-Hodgkin's malignant lymphoma in acquired immune deficiency syndrome

Hodgkin's disease (HD) after treatment of non-Hodgkin's lymphoma (NHL) has been reported but is extremely rare, and to the authors' knowledge has not been reported in patients with acquired immune deficiency syndrome (AIDS). The authors present a case of an AIDS patient who developed mixed cellularity type HD 2.5 years after chemotherapy and radiotherapy for Stage II NHL. The patient died of infectious causes 1.5 years after interferon therapy for the HD. Autopsy revealed Stage IV HD, mixed cellularity type.

Influenza in patients with human immunodeficiency virus infection

Although patients infected with human immunodeficiency virus (HIV) might be expected to have more severe illness due to influenza virus infection than normal persons, the course of influenza in such patients has not been well delineated. We describe six consecutive HIV-infected patients at San Francisco General Hospital in whom influenza virus was isolated from induced sputum or bronchoalveolar lavage specimens between December 1988 and March 1989. Although neither clinical presentation of influenza nor rate of secondary complications appeared to be altered from that in healthy individuals, our power of comparison was limited by small sample size. However, a high prevalence of hypoxemia and a trend toward prolonged duration of illness were identified. Larger, controlled studies are needed to define the course of influenza virus infection in HIV-infected patients as compared with nonimmunosuppressed patients.

Defective signal transduction--a common pathway for cellular dysfunction in HIV infection?

Qualitative defects in immune responsiveness after human immunodeficiency virus (HIV) infection have been well characterized and may play a key role in the development of HIV disease. However, no clear picture of the underlying mechanism of the functional deficiencies has yet emerged. In this article, Anthony Pinching and Keith Nye suggest that HIV or HIV proteins can sabotage transmembrane signalling and that this is of primary importance to the alterations in immune responsiveness.

Infections in the compromised host

The skin and/or mechanical factors, such as coughing, ciliary action or urine flow, along with phagocytes and humoral and cell-mediated immunity, help to protect the body from infection. In compromised patients, these mechanisms are impaired or bypassed, rendering patients susceptible to infection by opportunistic organisms (bacteria, mycobacteria, fungi, viruses, parasites). Mechanical barriers may be breached in patients with burns or indwelling catheters, in diabetics or cancer patients, and in parenteral drug abusers. Humoral or cell-mediated immunity may be suppressed in non-neoplastic patients following splenectomy, in diabetics, in alcoholics and in those with certain rheumatic disorders, as well as in patients undergoing haemodialysis or receiving steroids or immunosuppressive drugs. In cancer patients infection is often a cause of death, frequently occurring as a result of granulocytopenia, obstruction of natural passages, or suppression or dysfunction of humoral or cell-mediated immunity. Diagnosis of the infection may be difficult and expert advice should be sought. Treatment should be started before a conclusive diagnosis has been made, particularly in neutropenic patients since infections may be life-threatening.

Correction of human immunodeficiency virus-associated depression of delayed-type hypersensitivity (DTH) after zidovudine therapy: DTH, CD4+ T-cell numbers, and epidermal Langerhans cell density are independent variables

Twenty-four patients with various degrees of human immunodeficiency virus (HIV)-associated immunodeficiency were treated with zidovudine for up to 6 months. Nineteen of these patients had persistent depression of delayed-type hypersensitivity (DTH) responses prior to commencing therapy. In 11 of these 19 patients (58%) there was sustained improvement of DTH responses with the maximal effect occurring at approximately 3 months after therapy was started. DTH declined after 3 months but remained significantly higher than baseline at 6 months. Patients who did not have a sustained increase in DTH responses had more severe disease than those that did. Blood CD4+ T-cell counts increased in the majority of patients on zidovudine therapy, but varied independently of DTH responses. Epidermal Langerhans cell density was lower in HIV-infected patients than controls but also varied independently of DTH responses before and after zidovudine therapy. We suggest that sequential measurement of DTH responses is a valuable means of monitoring the restoration of cell-mediated immune responses by zidovudine in some HIV-infected patients. Our findings also demonstrate the need to define the processes involved in the restoration of DTH responses as this may lead to new approaches to the therapeutic manipulation of cell-mediated immune responses in HIV-infected patients.

Routine immunization of the HIV-positive asymptomatic patient

Physicians should develop the habit of considering, during initial routine and subsequent examinations of persons coming under their primary care, whether a vaccine is needed to establish or maintain universally recommend immunity. Furthermore, the physician should identify specific circumstances that call for special vaccines. Age, occupation, lifestyle, environmental risks, and diseases that compromise host defenses require systematic consideration.

Prevalence, clinical, and laboratory features of thrombocytopenia among HIV-infected individuals

Prevalence and clinical features of human immunodeficiency virus (HIV)-related thrombocytopenia have been investigated among a random population of 657 anti-HIV-positive individuals. A platelet count below 100 X 10(9)/liter was detected in 72 patients (10.9%). Compared with anti-HIV-positive controls with normal platelets, a significantly higher prevalence of males (p less than 0.02) and of intravenous drug abusers (p less than 0.02) as well as a higher frequency of patients with advanced HIV-related disease (p less than 0.001) were detected among thrombocytopenic patients. Those patients whose thrombocytopenia was associated with neutropenia and/or anemia (14 cases, 2.1%) clearly differed from patients with isolated thrombocytopenia (IT) (58 cases, 8.8%) since they belonged to the more advanced groups of the CDC classification of HIV-related disorders, had lower CD4-positive lymphocyte counts, a higher frequency of cutaneous anergy, and less persistent thrombocytopenia. In the cohort of patients with persistent IT (47 cases), no single epidemiological or clinical data proved to correlate with the severity of thrombocytopenia. They did not differ significantly from anti-HIV-positive controls in their distribution among CDC groups, but the total lymphocyte and the CD4-positive lymphocyte counts were significantly lower in IT patients belonging to CDC group II (p less than 0.05 and p less than 0.02, respectively) and III (p less than 0.01 and p less than 0.005, respectively) compared with CDC group-matched controls; after a median followup of one year, the two cohorts showed similar rates of progression to CDC Group IV.

Immunological features of human immunodeficiency virus disease

Infection with the human immunodeficiency viruses results in a profound immunosuppression responsible for most of the clinical features of AIDS. The virus devastates the immune system because its main target is the T4 lymphocyte, which is the key component for generating and regulating the immune response. The cellular receptor for HIV, the membrane glycoprotein CD4, is found mainly on the surface of this major subpopulation of T lymphocytes and also on many other cell types such as those of the monocyte/macrophage series. HIV can destroy CD4 cells by direct virus cytotoxicity and indirectly through the host response against HIV-infected cells or gp120-targeted cells. Cells of the macrophage lineage are generally not destroyed but serve as a reservoir of virus. HIV also causes functional impairment in T cells, B cells and monocytes. The virus can exist in latent or chronic form. The mechanisms of cellular destruction, viral persistence and conversion to a productive infection are being studied vigorously. Host factors that may affect clinical outcome and immunological markers that may predict progression of HIV disease are presently delineated. Prolonged serological latency may follow infection with HIV. Protective humoral and cell-mediated immune responses to HIV are either poor or not sustained. Recent results on HIV-specific cytotoxic T lymphocytes are of great interest. These cytotoxic cells, particularly those directed to gp120 targets, probably contribute to cellular damage. A central question regarding immunity to HIV is its beneficial versus deleterious effects, particularly in regard to the eventual development of an AIDS vaccine.

Zinc status in human immunodeficiency virus infection

Plasma zinc and copper concentrations, erythrocyte zinc concentration, copper-zinc superoxide dismutase activity and urinary zinc concentrations were determined for control subjects and individuals with AIDS, ARC, or asymptomatic HIV infection. Significant differences among the population groups were not noted for the above parameters with the exception of plasma copper which was higher in the AIDS group than in other patient groups. These results do not support the idea that zinc deficiency is a common contributory factor of HIV infectivity or clinical expression, nor that HIV infection induces a zinc deficiency.

Long-term preservation of whole blood samples for flow cytometry analysis in normal and HIV-infected individuals from Africa

A whole blood method requiring less than 4 ml of heparinized blood was developed to assess the practicality of preparing whole blood samples that could be easily stored, transported and readily used to determine the lymphocyte phenotypes and proliferation responses of individuals from remote areas who are infected with the human immunodeficiency virus. Minor modifications in standard whole blood procedure for lymphocyte phenotyping have significantly increased the stability of light scatter and fluorescence intensity of the cells for subsequent flow cytometry (FC) analysis. These changes include removal of lysis solution prior to fixation, fixation of monoclonal antibody-stained cells in 1% paraformaldehyde for 30 minutes and storage of fixed samples in medium containing 1% bovine serum albumin. Lymphocyte subsets and their functional subsets could reliably be determined on samples stored for up to 4 weeks. Further, blood samples could be kept at room temperature for up to 96 hours or at ambient temperature during transportation from Africa before staining for FC without affecting their quantitation. While samples could be processed for FC analysis under field-laboratory conditions, proliferation assays could only be performed on samples that were transported within 48 hours of their collection. The whole blood method saves time and expense and decreases the volumes of blood required to perform phenotypic analysis and functional assays on specimens collected in remote areas.