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Ex vivo interferon (IFN)- gamma -producing CD8 T cells specific for human immunodeficiency virus (HIV) Env, Gag, and Pol antigens were measured in the peripheral blood of 55 children not receiving highly active antiretroviral therapy (HAART) and 70 children receiving HAART. In children not receiving HAART, the frequency of HIV-specific IFN- gamma -producing CD8 T cells was positively correlated with age and was not associated with plasma viral load or CD4 T cell levels. In children receiving HAART, the frequency of HIV-specific IFN- gamma -producing CD8 T cells was directly correlated with plasma viral load, and its association with age remained significant. In conclusion, the frequency of HIV-specific IFN- gamma -producing CD8 T cells in children is primarily determined by both age and plasma viral load. Copyright © 2005 Infectious Diseases Society of America [ABSTRACT FROM AUTHOR]

SUMMARY We studied immune reconstitution against the parasite T. gondii in HIV-infected patients treated for 1 years with highly active antiretroviral therapy (HAART). We used SCID mice, humanized with peripheral blood mononuclear cells (PBMC) from patients, which were then infected with T. gondii cysts. Mice humanized with PBMC from patients before the start of HAART were highly susceptible to infection. In contrast, mice humanized with PBMC from patients who had received HAART for 6 months displayed higher survival rates, correlating with lower intracerebral parasite loads. However, this resistance was lost during follow up because mice humanized with PBMC from patients treated with HAART for 12 months survived for no longer than mice that had not been humanized. Specific lymphocyte proliferation assays showed that the increase in proliferative response depended on treatment duration and that HAART induced changes in IFN-γ secretion in the presence of Toxoplasma antigens. Thus, our results indicate partial immune reconstitution against T. gondii in HIV-infected patients following HAART, possibly due to changes in the patterns of specific IFN-γ production and redistribution of functional memory CD4+ cells. [ABSTRACT FROM AUTHOR]

To determine whether viral load rebounds during HAART impact on CD4+ T cell recovery and immune reconstitution, we studied a prospective cohort of 355 antiretroviral naive patients enrolled to be randomized in a trial of three strategies of induction/maintenance HAART. The extent of immune reconstitution in blood through 72 weeks of antiretroviral treatment was evaluated. Lymphocyte subset markers (CD4, CD8, CD45RA, CD62L, CD16, CD19), activation markers (HLA-DR, CD38, CD25) were performed by cytometry analysis. Our results showed that plasma HIV-1 RNA was suppressed to below 500 copies per ml through week 72 in 240 patients (group 1) while the remaining 115 patients experienced at least one viral rebound (group 2). At baseline, CD4 cell count was higher and HIV-1 RNA was lower in group 1 than in group 2. Over 72 weeks, mean increase in CD4+ T cell count was 0·32 cell/mm3/day in group 1 and only 0·14 cell/mm3/day in group 2 (P < 0·0001). However, the patterns of changes in CD4+ and CD8+ T cell subsets during therapy were very similar across the two groups with only subtle and very limited differences. We conclude that permanent control of HIV replication could be necessary for faster immune reconstitution. [ABSTRACT FROM AUTHOR]

NK cell activity is impaired in HIV-infected patients. The mechanisms behind the altered NK functions are not clear, and conflicting data concerning NK and antibody-dependent cellular cytotoxicity (ADCC) activity have been reported. In order to investigate whether this impairment is also observed at the clonal level and whether it is related to a defect at the target cell binding and/or the post-binding level, we evaluated highly purified NK cell lines and cloned NK cells obtained from 22 HIV-infected patients at different stages of disease and compared them with normal controls for their ability to: (i) kill K-562 and U-937 cell lines using a 51Cr release assay; (ii) bind and kill K-562 and U-937 cells at the single cell binding level; (iii) release NK cytotoxic factor (NKCF), tumour necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ); (iv) kill anti-IgM preincubated Daudi cell line (ADCC activity). This study with cloned NK cells or NK ceil lines from HIV-infected individuals showed: (i) a decrease in their lytic capability against target cell lines; (ii) a low ability to form conjugates with K-562 and U-937 ceil lines with respect to controls; (iii) a decreased ability to kill bound target cells; (iv) low levels of released NKCF. TNF-α and IFN-γ after incubation with U-937 cells. Taken together, these findings suggest that the impaired NK cell function during HIV infection is also observed at the clonal level and is related lo defects both at the target and post-binding levels. However, the precise mechanisms remain to be determined. The inability to restore normal NK activity after long-term culture in the presence of high levels of recombinant IL-2 is in agreement with the hypothesis of a "general anergic process during HIV infection". [ABSTRACT FROM AUTHOR]

B cell subpopulations, as defined by double-labelling techniques with CD5 and CD19 monoclonal antibodies (MoAbs), were serially studied in 335 HIV-1 seropositive patients. At the time of the first consultation, no important modifications in either CD5+ or CD5- subpopulations were observed, whatever the stage of the disease. However, in 18 out of the 335 patients (5.37%), a sharp increase in B cells exceeding 20%, and 300/mm³ was observed. This increase in B cells was mainly accounted for CD5-CD19+ B cell subpopulations and was associated with: (i) evolution of the disease, since only four patients presented it at their first consultation (one lymphadenopathy-associated syndrome (LAS) and three AIDS); (ii) advanced stages of disease since, at the time of B cell augmentation, two patients were staged as LAS, four as ARC and 12 as AIDS; (iii) a high incidence of non-Hodgkin's lymphomas (NHL) since three out of the 18 patients presented a histologically confirmed NHL and three others a clinical pattern compatible with this diagnosis. However, in three patients with B hyperlymphocytosis, polymerase chain reaction (PCR) studies of immunoglobulin gene rearrangement revealed the existence of a polyclonal expansion of B cells. These results justify inclusion of a pan-B cell marker in routine phenotypic studies of HIV-infected individuals, as well as the search for NHL among patients presenting this abnormality. [ABSTRACT FROM AUTHOR]

One of the major routes for modulating HIV-1 expression by infected T cells is through the control of transcription initiation from the HIV-1 long terminal repeat (LTR), which is regulated either by its own viral gene products or by several cellular DNA-binding proteins induced during T cell activation. Previous work reported preferential HIV-1 infection and replication of memory CD4 T cells from infected individuals, which was explained either by a higher viral burden of this subset or by differences between naive and memory cells in the activation of the general transcription machinery involved in HIV-1 replication. In this work, we have studied HIV-1 replication by highly purified naive and memory CD4 T cells from asymptomatic seropositive carriers (ASC) and AIDS patients following different activation signals. Our results demonstrate that viral replication in memory cells from ASC was observed after mitogenic (phytohaemagglutinin (PHA) and/or phorbol myristate acetate (PMA)) recombinant tumour necrosis factor-alpha (rTNF-α) and CD3-mediated activation. In contrast, in naive subsets, early viral replication was almost exclusively observed upon CD3- mediated activation. AIDS patients are characterized by similar levels of viral replication in both subsets after PHA and soluble or immobilized anti-CD3 MoAb activation. However, naive subsets from AIDS patients still displayed differential requirements since they failed to replicate HIV-1 after treatment with PMA and rTNF-α. Taken together, these results provide evidence that HIV-1 replication inCD4+ T cells from infected individuals is a function of the differentiation stage of the cells, the disease stage of the patient and the activation signal employed. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate serum levels of TNF-α, sIL-2R and distribution of peripheral leucocyte subsets in patients with advanced neoplastic disease undergoing IPLD treatment. Fifteen cancer patients with evidence of persistent disease were further divided in two groups according to outcome at the end of the period of clinical evaluation: group 1 patients were still alive and group 2 patients had died. Our results show: (i) an increase in the initial level of TNF-α in both groups: (ii) a decrease in TNF-α levels during the follow up of group I patients; (iii) a significant increase in serum levels of sIL-2R in patients in group 2 compared with those in group 1; (iv) a progressive and constant increase in TNF-α levels in group 2; (v) a decrease in CD4+CD45RA+ subpopulation in both groups: (vi) an increase in CD25+ cells: (vii) an increase in CD4+, CD4+CD45RA+ and CD25+ cells during the follow up of group 2 patients. The data generated here form the basis for further investigations on the use of IPLD as a single agent and in combination with other biological response modifiers in cancer patients. [ABSTRACT FROM AUTHOR]

Purified naive and memory CD4 T cells from healthy donors, HIV&plus; asymptomatic carriers and AIDS patients were examined for their proliferative activity and their pattern of cytokine secretion (IL-4, IL-6, interferon-gamma (IFN-γ) and tumour necrosis factor-alpha (TNF-α) upon stimulation with phytohaemagglutinin (PHA), phorbol myristate acetate (PMA) and cross-linked anti-CD3 MoAb, in the presence of recombinant lL-2 (rIL-2). We found a decrease in the proliferative capacity of naive CD4 T cells following stimulation with PHA and PMA, and a sharp decline in this response upon cross-linked anti-CD3 stimulation in both subsets, although it predominated in the naive subpopulation. In AIDS patients, less pronounced impairment of thymidine uptake by the naive subset was found upon PHA and cross-linked anti-CD3 MoAb stimulation. In addition, an altered secretion pattern of the different cytokines was observed, consisting of abnormal secretion of IL-6 by both naive and memory cells, an abnormal pattern of IFN-γ secretion and frequent loss of detectable 1L-4 production by HIV patients. These abnormalities were even more pronounced in AIDS patients than in the asymptomatic carriers. Overall, our results extend previous reports indicating functional impairment of memory CD4 subsets in HIV&plus; subjects by showing that this impairment involves naive CD4 T cells. [ABSTRACT FROM AUTHOR]

T and B cell human responses to European bat lyssavirus (EBLI) induced by post-exposure rabies vaccination (PM virus vaccine) were evaluated by measuring plasmatic titres of EBLI-specific neutralizing antibodies; specific EBLI-binding antibodies; and proliferation indices of peripheral blood lymphocytes stimulated in vitro with EBLI. These parameters for vaccination efficacy were compared with those obtained with vaccine-related viruses (CVS and ERA) and with a non-vaccine- related virus, Mokola virus, the last implicated in vaccination failures. Twenty-two patients exposed to rabies risk who received a reduced rabies post-exposure vaccination were involved in the study. On day 21, vaccine induced CVS-specific neutralizing antibodies in all patients; but EBLI-specific neutralizing antibodies were induced in only 73% of patients. No vaccinee had Mokola-specific neutralizing antibodies. Patients having EBLI-specific neutralizing antibodies were usually those in whom vaccination induced high titres of CVS-specific neutralizing antibodies. On day 21, peripheral blood lymphocytes of 86% of patients could be restimulated in vitro with vaccine, 43% with EBLI and 45% with Mokola. Patients exhibiting a high vaccine-specific proliferation response more likely developed an EBLI - or a Mokola-specific proliferative response. No correlation was found between T and B cell responses. Rabies vaccination induced neither T nor B cell EBLI -specific responses in 22% of patients. [ABSTRACT FROM AUTHOR]