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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Simian immunodeficiency virus (SIV) infects a small number of CD4+ T cells including "memory" T cells. The following describes the cell surface markers which may delineate subsets of CD4+ memory T cells and reviews how memory CD4+ T cells are activated and regulated through the T-cell receptor and such accessory receptors as CD28. The factors which may influence initial expression and infection of T cells by CD4 are discussed. Unlike activated and infected T cells, unstimulated CD4+ T cells have little or no SIV DNA detectable in the genomic fraction, but key activation signals may promote integration of viral DNA in memory T cells. Bacterial superantigens (SuperAg) can promote increased levels of SIV viral DNA in mature and immature T cells. Immunodeficiency virus products such as gp120, Nef, and Tat can affect CD4+ T-cell function. Whereas Nef can reduce expression of CD4, Tat reduces the expression of CD28. We hypothesize that the lack of expression of key accessory molecules on CD4 lineage T cells infected with immunodeficiency viruses may make infected T cells more susceptible to recall-antigen-induced programmed cell death.
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PMID:Macaque CD4+ T-cell subsets: influence of activation on infection by simian immunodeficiency viruses (SIV). 134 28

With the advent of standard flow cytometric methods using two-colour fluorescence on samples of whole blood, it is possible to establish the ranges of CD3, CD4 and CD8 T lymphocyte subsets in the routine laboratory, and also to assist the definition of HIV-1-related deviations from these normal values. In 676 HIV-1-seronegative individuals the lymphocyte subset percentages and absolute counts were determined. The samples taken mostly in the morning. The groups included heterosexual controls, people with various clotting disorders but without lymphocyte abnormalities as well as seronegative homosexual men as the appropriate controls for the HIV-1-infected groups. The stability of CD4% and CD8% values was demonstrated throughout life, and in children CD4 values less than 25% could be regarded as abnormal. The absolute counts of all T cell subsets decreased from birth until the age of 10 years. In adolescents and adults the absolute numbers (mean +/- s.d.) of lymphocytes, CD3, CD4 and CD8 cells were 1.90 +/- 0.55, 1.45 +/- 0.46, 0.83 +/- 0.29 and 0.56 +/- 0.23 x 10(9)/l, respectively. In patients with haemophilia A and B the mean values did not differ significantly. In homosexual men higher CD8 levels were seen compared with heterosexual men and 27% had an inverted CD4/CD8 ratio but mostly without CD4 lymphopenia (CD4 less than 0.4 x 10(9)/l). However, some healthy uninfected people were 'physiologically' lymphopenic without having inverted CD4/CD8 ratios. When the variations 'within persons' were studied longitudinally over a 5-year period, the absolute CD4 counts tended to be fixed at different levels. As a marked contrast, over 60% of asymptomatic HIV-1+ patients exhibited low CD4 counts less than 0.4 x 10(9)/l together with inverted CD4/CD8 ratios. Such combined changes among the heterosexual and HIV-1-seronegative homosexual groups were as rare as 1.4% and 3%, respectively. For this reason, when the lymphocyte tests show less than 0.4 x 10(9)/l CD4 count and a CD4/CD8 ratio of less than unity, the individuals need to be investigated further for chronicity of this disorder, the signs of viral infections such as HIV-1 and other causes of immunodeficiency.
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PMID:Laboratory control values for CD4 and CD8 T lymphocytes. Implications for HIV-1 diagnosis. 134 72

To identify the target proteins of CD8+ T lymphocytes we have explored the cytolytic immune responses of 12 rhesus macaques experimentally infected with the simian immunodeficiency virus (SIVmac). Target cells were autologous B cell lines presenting SIVmac proteins after infection with recombinant vaccinia viruses. The eight following proteins were studied: ENV, POL, GAG, NEF, VIF, REV, TAT, and VPX. Macaque PBMC stimulated with Con A and expanded in T cell growth factor-containing medium produced cell lines with cytolytic activity in the majority of infected animals (9/12). The structural proteins ENV, POL, and GAG were recognized by cell lines derived from nine, eight, and six macaques, respectively. The small regulatory proteins also represented efficient CTL targets, a specific activity being detected against NEF (8/12), REV (7/12), VPX (7/12), TAT (6/12), and VIF (5/12). Most cytotoxic responses (except those directed against ENV) were mediated by CD8 cells and were MHC class I restricted. Limiting dilution analysis allowed us to quantify the frequency of CTL precursors and confirmed the high immunogenicity of multiple SIV proteins. Three different patterns of response could be defined: six animals were able to recognize at least six of the eight tested target proteins, two of them reacting with all eight target proteins. The other three responder macaques reacted only against a few SIV proteins, whereas no cytotoxic activity was detected in the three remaining infected macaques and in the nine negative controls. The six animals responding against multiple proteins were still healthy 12 to 22 mo after infection with two of them presenting a decrease in circulating CD4 cells concurrently to the disappearance of the CTL response. Conversely, three nonresponder or low responder macaques developed an overt disease after 4 to 12 mo, and two other presented a very low level of CD4 cells, suggesting that the pattern of response may be of prognostic value.
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PMID:Cytotoxic T lymphocyte response against multiple simian immunodeficiency virusA (SIV) proteins in SIV-infected macaques. 134 22

Interaction between herpesviruses and human immunodeficiency virus (HIV)1 is postulated in the progression of HIV disease. In order to evaluate the specific antibody responses directed to Epstein-Barr virus (EBV) and cytomegalovirus (CMV) and to provide serological evidence suggesting reactivation of these viruses able to accelerate the immunodeficiency, we studied IgA and IgG titres to EBV and CMV in the serum of HIV positive patients in relation to the CD4 cell number. The titres of IgG antibodies to EBV and the prevalence of IgG to CMV were significantly higher in HIV positive patients compared to control high risk HIV negative subjects. In HIV infected patients, anti-VCA IgG antibodies increased and anti-EBNA IgG antibodies decreased progressively in relation to the decline of CD4 cell number whereas anti-CMV IgG antibodies did not varied significantly at the same time. Anti-VCA IgA and anti-EA IgG antibodies were found uncommonly and with low titres. IgA antibodies to EA and CMV were not detected in any patient. The variations in EBV antibody response that we describe in HIV infection were previously reported in other immunodeficiency states and could be distinctive of these diseases.
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PMID:Antibodies to Epstein-Barr virus and cytomegalovirus in relation to CD4 cell number in human immunodeficiency virus 1 infection. 134 40

The product-limit incidence of Mycobacterium avium-intracellulare complex (MAC) bacteremia in 1006 human immunodeficiency virus (HIV)-positive patients followed at one institution over a 3-year period from the day of AIDS diagnosis with monthly lysis-centrifugation blood cultures was 21% +/- 2% SE at 1 year and 43% +/- 3% at 2 years. The product-limit incidence of MAC bacteremia at 1 year after the patients' first CD4 cell count was related to both the CD4 cell count and to whether they had an AIDS diagnosis (both P less than .0001) but not to age, sex, or race. This incidence was 39% +/- 6% for CD4 cell counts of less than 10/mm3, 30% +/- 5% for 10-19/mm3, 20% +/- 4% for 20-39/mm3, 15% +/- 4% for 40-59/mm3, 8% +/- 3% for 60-99/mm3, and 3% +/- 1% for 100-199/mm3. MAC may eventually infect most if not all HIV-positive patients who do not die from another HIV-related event.
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PMID:Incidence of Mycobacterium avium-intracellulare complex bacteremia in human immunodeficiency virus-positive patients. 134 6

The mechanism for the gradual loss of CD4+ T lymphocytes and the development of the slowly progressive inflammatory/degenerative lesions that accompany human immunodeficiency virus infection are poorly understood. Using the Simian immunodeficiency virus (SIVmac) macaque model of AIDS, we found that persistently infected primary macrophages fuse with primary activated CD4+ lymphocytes and that this interaction results in production of tumour necrosis factor-alpha (TNF alpha) and interleukin 6 (IL-6). An earlier report had shown that SIV-infected macaque macrophages fuse with CEM174 cells (a human CD4+ cell line) and cause their lysis. In the present report, we have shown that TNF-alpha and IL-6 are also produced during the early stages of this interaction. Data from cocultivation of infected macrophages with several CD4+ T cell lines, including CEM174, suggested that the cytokines are produced by the T cells, and that cytokine production is restricted to those cells which not only express CD4, but are also capable of fusing with the infected macrophages. These data suggest that infected macrophages in vivo could fuse with and eliminate activated CD4+ lymphocytes and, during this interaction, release cytokines, which would contribute to the degenerative and inflammatory lesions characteristic of this disease.
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PMID:Tumour necrosis factor and interleukin 6 production during interaction between activated CD4+ lymphocytes and simian immunodeficiency virus-infected macrophages. 135 Mar 3

Coinfection with the human immunodeficiency virus (HIV) and Treponema pallidum may predispose to accelerated neurosyphilis. The mechanism underlying this interaction is undefined, but usually presumed to result from HIV-induced suppression of cell-mediated immunity as reflected in the CD4 T-lymphocyte count. We report a patient infected with HIV who developed aggressive neurosyphilis despite a CD4 count of 1000/mm3. The CD4 cells constituted 17% of his total lymphocytes. Our case suggests that while severe neurosyphilis can occur in HIV-infected persons with normal absolute CD4 counts, the percentage of CD4 cells may be a better indicator of the risk of neurosyphilis. These observations are relevant to designing treatment strategies for patients coinfected with HIV and T pallidum based on measures of their immunocompetence.
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PMID:Acute syphilitic meningitis in a man with seropositivity for human immunodeficiency virus infection and normal numbers of CD4 T lymphocytes. 844 16

1. The expression of the gene codifying for CD4, the most important human immunodeficiency virus type 1 (HIV-1) receptor molecule, was analyzed in 11 fetal brains at various gestational ages and in 9 human neuroblastoma (NB) cell lines. CD4 gene expression in fetal and malignant neural cells was then compared with that observed in a hematopoietic cell line and adult hippocampus. 2. In addition, CD4 mRNA was evaluated in two NB cell lines induced to differentiate in vitro with retinoic acid (RA) or 1-(5-isoquinolinyl-sulfonyl)-2-methyl piperazine (H7), a protein kinase C inhibitor. 3. All fetal brains and NB cell lines express a 1.8-kb signal when hybridized with pT4BcDNA probe, while a 3.0-kb signal such as observed in hematopoietic human cells was found in 1 of 11 fetal brains and in 0 of 9 NB cell lines. The 1.8-kb signal was lost in all analyzed poly(A)+ mRNA samples. 4. Moreover, CD4 gene expression was not induced in either RA- or H7-treated NB cells at any tested time and dose. The analysis of NB cells by polymerase chain reaction failed to demonstrate CD4 expression in either poly(A)+ or poly(A)- RNA. 5. In conclusion, the results show that the 1.8-kb signal observed in RNA extracted from fetal or transformed human neural cells is probably due to an aspecific hybridization. However, the gene codifying for CD4 can rarely be expressed by fetal brain cells early during gestation, in still unclear circumstances.
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PMID:Analysis of CD4 gene expression in human fetal brain and neuroblasts. 135 Sep 44

Cells expressing human immunodeficiency virus type 1 (HIV-1) tat can transactivate the HIV-1 long terminal repeat (LTR) in cocultured T lymphocytes. In this report, we describe the molecular requirements for transcellular activation of the LTR in Jurkat cells. An analysis with deletion mutants and blocking antibodies demonstrated a requirement for env expression in addition to tat expression for transcellular activation to occur. The results suggest that the transient association of CD4 and gp120 in cocultured cells is required for tat-mediated transcellular activation. The events that follow CD4-gp120 binding in transactivation, however, do not require the gp120-neutralizing domain, in contrast to HIV-mediated fusion and infection. The consequences of this interaction on cellular function are currently under investigation.
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PMID:Transcellular activation of the human immunodeficiency virus type 1 long terminal repeat in T lymphocytes requires CD4-gp120 binding. 135 Nov 4

Identification of laboratory tests that can help predict progression to acquired immunodeficiency syndrome (AIDS) in people infected with human immunodeficiency virus (HIV) is important for clinical management and counselling. We have assessed the usefulness of CD4 lymphocyte count, serum beta 2-microglobulin concentration, and the presence of p24 antigen as predictors of AIDS. We studied 214 homosexual and bisexual men with well-defined dates of HIV seroconversion. For each participant, we defined the baseline date as the earliest date before the development of AIDS on which the three laboratory tests were done. beta 2-microglobulin concentration at baseline was in all analyses an independent predictor of AIDS, even after stratification by baseline CD4 count, duration of HIV infection, or use of zidovudine before or at baseline. For example, among men with at least 0.5 x 10(9)/l CD4 cells who were negative for p24 antigen, the risks of AIDS at 12 months and 24 months were 1% and 5%, respectively, for those whose beta 2-microglobulin concentrations were below 4.0 mg/l, compared with 17% and 27%, respectively for those with beta 2-microglobulin concentrations above that cut-off point (p less than 0.001). Among men with an estimated duration of infection of 5 years or less, beta 2-microglobulin concentration was the strongest independent predictor of AIDS. Measurement of serum beta 2-microglobulin adds important prognostic information to CD4 count in determining the risk of progression to AIDS in HIV-infected subjects, including those whose CD4 cell count has not yet fallen.
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PMID:Serum beta 2-microglobulin and prediction of progression to AIDS in HIV infection. 137 63


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