Endogenous cytokine production protects T cells from spontaneous apoptosis during highly active antiretroviral therapy.

BACKGROUND: The availability of therapeutic regimens that effectively interfere with HIV-1 replication provides novel opportunities to investigate mechanisms of T-cell depletion as well as repopulation in infected individuals. METHODS: Nineteen HIV-1-infected individuals were investigated during one-year follow-up of highly active retroviral therapy (HAART). The frequencies of apoptotic T cells, as determined by propidium iodide, staining, TUNEL assay and analysis of annexin V, were assessed either in the absence or in the presence of anti-interleukin (IL)2 and anti-IL-4 neutralizing Ab. Spontaneous and lectin-induced cytokine production were assessed by ELISA. RESULTS: Increments of both naive and memory CD4 and CD8 T cells during HAART are accompanied by a decrease of T-cell apoptosis that, after 12 months of HAART, reaches normal levels. This is associated with increments of both spontaneous and activation-induced production of IL-2 and IL-4 by peripheral blood mononuclear cells (PBMCs), though only the latter was found defective at enrolment. During HAART, blocking of either IL-2 or IL-4 production by PBMCs using neutralizing Ab restores levels of T-cell apoptosis consistent with those determined at enrolment. These data suggest that both IL-2 and IL-4 produced by PBMCs during HAART provide anti-apoptotic signals that can contribute to an increased survival of T cells and may thus play a part in long-term immune reconstitution. CONCLUSIONS: An effective viral suppression and, possibly, effects of PI on molecular targets other than viral components, can support a progressive normalization of T-cell survival that, at least in part, depends upon the restoration of proper soluble signals. These results provide evidence of a supporting role of endogenous cytokine production in peripheral T-cell repopulation during an effective and prolonged viral suppression. This may be relevant for the definition of immune-intervention targets aimed at immune reconstitution in HIV-1-infected patients.

Distribution of the natural killer-related receptor for HLA-C during highly active antiretroviral therapy for human immunodeficiency virus infection.

Receptors interacting with Major Histocompatibility Complex class I molecules have been initially found on the surface of human natural killer (NK) cells, where they deliver inhibitory signals to the lysis, being thus defined killer inhibitory receptors (KIR). Subsequently, they were detected also on the surface of T-CD8(+) lymphocytes and are particularly expanded during human immunodeficiency virus (HIV) infection, where they downregulate HIV-specific cytolysis. The expression of KIR recognizing human leukocyte antigen-C alleles was assessed in HIV-infected patients, undergoing highly active antiretroviral therapy (HAART). To this end, the combined expression of CD16/CD56, of CD3 and CD8 as well as of KIR (CD158a and CD158b) surface molecules was analyzed on peripheral blood mononuclear cells by monoclonal antibodies, and flow cytometry. An increase of CD3(+)CD8(+)CD158b(+) cells was found after 6 months of HAART. This finding may have implications for the regulation of T-cell mediated cytolysis during HAART.

Recovery of hematopoietic activity in bone marrow from human immunodeficiency virus type 1-infected patients during highly active antiretroviral therapy.

The mechanisms responsible for the hematopoietic failure in human immunodeficiency virus type 1 (HIV-1)-infected patients are still unknown. Several findings indicate that the in vitro proliferative potential of precursor cells from AIDS patients is reduced. The changes seen in bone marrow (BM) morphology and the defective BM functions associated with cytopenias have both been proposed as potential explanations. In patients treated with highly active antiretroviral therapy (HAART) an immune reconstitution associated with increased whole blood cell counts has been described. We have investigated the effects of HAART on the number of colony-forming cells (CFCs) and long-term culture-initiating cells (LTC-ICs), using long-term BM cell cultures (LTBMC) in a group of subjects with HIV-1 infection enrolled in an open study to evaluate the mechanisms of immune reconstitution during HAART. In each patient, the increase in colony growth was homogeneous, regardless of the type of hematopoietic progenitor cells assayed; in four subjects an increase in the most primitive progenitor cells (LTC-ICs) was observed. These findings were associated with the in vivo data showing increased numbers of BM mononuclear cells (BMMCs) after HAART and with a rise in peripheral CD4(+) T cell counts and decreased levels of plasma HIV-1 RNA. A decreased number of hematopoietic progenitor cells and/or a defective modulation of progenitor cell growth might be the cause of the hematological abnormalities in AIDS patients. Controlling HIV-1 replication by HAART could determine a restoration of stem cell activity, probably because of the suppression of factors that inhibit normal hematopoiesis.

Decreased T cell apoptosis and T cell recovery during highly active antiretroviral therapy (HAART).

T cell apoptosis represents a common mechanism of T cell depletion in HIV-1-infected individuals reflecting maturational and functional T cell abnormalities either directly or indirectly induced by the virus. In the present study, the effects of highly active antiretroviral therapy (HAART) on the spontaneous apoptosis of distinct T cell subsets were investigated during a 6-month follow-up in a cohort of HIV-1-infected individuals with CD4(+) cell counts between 100 and 500 cells/microliter and plasma HIV-1 RNA levels >/=10, 000 copies/ml. We determined that the rapid and sustained increase of both naive (CD45RA(+)CD62L(+)) and memory (CD45R0(+) and CD45RA(+)/CD62L(-)) CD4(+) and, to as lesser extent, CD8(+) T cells in peripheral blood was associated with a significant decrease of apoptotic CD4(+) and CD8(+) as well as CD3(+)CD4(-)CD8(-) T cells. Among CD4(+) lymphocytes, at enrollment, the highest frequency of apoptotic cells was observed within the memory compartment, as defined by CD45R0 expression. During HAART, however, the frequency of CD4(+)CD45R0(+) apoptotic T cells progressively decreased in association with a significant downregulation of surface activation markers that indicated decreased levels of systemic immune stimulation. These results indicate that effective viral suppression can contribute to progressive normalization of maturational and functional T cell abnormalities responsible for the high levels of T cell apoptosis in HIV-1-infected individuals. This, in turn, may contribute to a reduced rate of T cell loss and immune reconstitution during HAART.

Evaluation of T-cell response to CD3 plus CD28 monoclonal antibodies in HIV-1 infected subjects treated with highly active antiretroviral therapy.

To investigate whether highly active antiretroviral therapy (HAART) could improve CD28 molecule expression and CD28-costimulation pathway function we tested the effect of CD28-costimulation on T cell receptor/CD3 induced proliferative responses in a group of HIV-1-infected subjects with CD4+ cells>200/mmc before and after HAART. CD3-mediated responses are recovered or improved after HAART. However the ability of potentiating the responses through CD28-costimulation seemed conserved before therapy and decreased in parallel with increase of response to CD3 alone. These results confirm the integrity of CD28-pathway of costimulation in patients with CD4+ cells>200/mmc and suggest an inverse correlation between magnitude of response to CD3 alone and increase of CD3 response due to anti-CD28 addition.

Long-term evaluation of T-cell subsets and T-cell function after HAART in advanced stage HIV-1 disease.

OBJECTIVES: Evaluation of immunological reconstitution after 2 years of highly active antiretroviral therapy (HAART) in AIDS patients. DESIGN: Previous data showed the effectiveness of HAART but conflicting evidence of immune reconstitution has been found in severely immunocompromised patients. Therefore, T-cell subsets and functions were analysed during 24 months of HAART in 21 AIDS patients (mean baseline CD4 cell count, 20 x 10(6)/l). METHODS: Subjects were tested at baseline and after 4, 12 and 24 months of therapy for clinical symptoms and the following investigations were carried out: plasma HIV RNA, T-cell subsets and lymphoproliferative responses to mitogens (phytohaemagglutinin, anti-CD3), and recall antigens (Candida mannoprotein, tetanus toxoid and recombinant glycoprotein 160). RESULTS: Increase in body weight, improvement of Karnofsky's score and reduction of opportunistic infections were observed. All patients showed an initial increase in the CD4 memory subset, whereas naive CD4 cells consistently increased only after 1 year. The magnitude of immune recovery was stronger in patients showing a significant reduction in viral load. However seven out of 21 patients who did not reach a sustained suppression of viral load showed also an increase in T-cell subsets. The majority of patients recovered lymphoproliferative responses to mitogens, whereas only four subjects showed a functional response to Candida mannoprotein. No patients showed a response to HIV recombinant glycoprotein 160 or tetanus toxoid. CONCLUSIONS: The immune recovery observed is slower and not complete in severely immunocompromised patients. Our data suggest that HAART may be continued also in the absence of a significant HIV RNA decrease if alternative drugs are not available.

The Italian quality control study for evaluation of CD4 cells in centres involved in the treatment of HIV-1 patients. Italian CD4 Quality Control Group.

We report on the experience of establishing a national network for a quality control programme in evaluating CD4 cell counts in most Italian centres involved in the care of patients with HIV disease. The 68 centres were divided according to their geographical location into eight groups, and twice a year (tests A and B) they received three coded whole blood samples (two were replicates of the same sample) obtained from two informed HIV+ patients, one with CD4 counts/mm3 expected to be < 200 and one with values > 300. The medians of the determinations performed by the labs involved in each of the eight areas were taken as the 'true' values for each sample. Unsatisfactory performances for percentage of CD4 cells were identified as a CD4 analysis with residual values > or = +/- 5% and with deviates > or = +/- 2. For absolute numbers of CD4 cells, an unsatisfactory performance was defined as CD4 counts with residual > +/- 100 CD4 cells/mm3 and with deviates > or = +/- 2. The residual value is the CD4 value reported by each lab minus the median value. The deviate is the residual divided by the modified interquartile range (IQR x 0.75). Most of the centres provided reliable results. However, some labs failed to provide satisfactory results for percentages (6.25% of the tested labs for test A and 6.17% for test B) or absolute numbers (16.25% test A and 12.34% test B). Only 3.7% of the labs gave unsatisfactory results in both tests. Four of the unsatisfactory results from the two tests gave an error in absolute numbers > +/- 200 CD4 cells/mm3. Our data suggest that most Italian labs provide reliable results in evaluating the numbers of CD4 cells in HIV-1+ samples, but the importance of running a quality control programme is highlighted by our experience with those centres which provide unsatisfactory data which may lead to incorrect classification of the patients or assessment of treatment.

Long-term evaluation of cellular immunity during antiretroviral therapy and immunization with human immunodeficiency virus type 1 (HIV-1) Env glycoprotein in HIV-1-infected persons.

Cellular immune responses to human immunodeficiency virus type 1 (HIV-1) antigens, microbial recall antigens, and CD3 monoclonal antibody were studied in HIV-1-infected asymptomatic patients in a phase II, double-blind trial of immunization with recombinant HIV-1 gp160 in or not in association with zidovudine. A vigorous and persistent lymphoproliferative response (LPR) to HIV-1 Env antigens was observed in vaccinated patients. Neither Env-specific lymphocyte cytotoxicity nor LPR to recall antigens was significantly influenced by gp160 administration. The induction of LPRs to HIV-1 envelope proteins did not show positive effects on the course of HIV-1 infection. Patients treated with zidovudine alone or in combination with the immunogen showed improvement of T lymphocyte responses and transient reduction of viremia. These results suggest that antiretroviral therapy is more beneficial than immunization with gp160 and should always be considered in association with future vaccination and immunotherapeutic interventions in HIV-1-infected subjects.

[Diffusion of hepatitis B surface antigens in subjects with bladder schistosomiasis]. / Ulteriore contributo sulla diffusione dell'antigene di superficie dell'epatite B in soggetti con schistosomiasi vescicale.

The problem of the relationship between the surface B antigen and the parasitosis characterized by active penetration of the larvae through the skin has not yet been resolved. Conflicting results have been reported lately on this problem even though it is currently believed that HBsAg is found more often among patients infected by parasites than among healthy subjects. Serum samples from 67 Somalian patients infected by S. haematobium were tested for the presence of the surface B antigen by ELISA method. The HBsAg was found in 19.4 per cent of these patients, while among controls (90 cases) the frequency of HBsAg was of 10 per cent. A comparative analysis of the results obtained with various methods in Somalia shows that the frequency of HBsAg among subjects with urinary schistosomiasis is of 25.9 per cent with indirect haemoagglutination (IHA), of 19.4 per cent with ELISA method and of 14.8 per cent with radioimmunoassay (RIA). These observations seem to indicate that the problem of an increased frequency of HBsAg among patients with urinary schistosomiasis needs further investigation.