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Query: UMLS:C0001175 (AIDS)
 120,706 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied follicles in sections of lymph nodes and spleen from cynomolgus monkeys (Macaca fascicularis) after infection with simian immunodeficiency virus (SIVsm), by (immuno)histology and (immunogold) electron microscopy. Also isolated follicular dendritic cells (FDC) were investigated. Histology showed ranged from follicular hyperplasia to follicle fragmentation. FDC showed desmin and vimentin, characteristic of mesenchymal cells. Except for two animals who got experimental chemotherapy in the first postinfection period, the cells expressed SIV gag p28 protein. Electron microscopy showed SIVsm-like particles in the germinal centers. A number of cell types in the germinal center, including FDC, showed tubuloreticular structures, indicative of alpha-interferon synthesis during an antiviral response. In immunogold electron microscopy, SIV p28 label was observed on the surface of FDC, on SIVsm-like particles, and in the cytoplasm of macrophages. A relatively high density of CD8-positive cells (T cytotoxic-suppressor phenotype) was observed around and in germinal centers, especially areas depleted of FDC. Cells immunoreactive for serine esterase granzyme-B, a protein occurring in granules of cytotoxic cells, occurred around germinal centers, but not in germinal centers at areas where FDC and SIV p28 label localized. This argues against a role of cytotoxic T cells in mediating follicle destruction.
AIDS Res Hum Retroviruses 1992 Dec
PMID:Simian immunodeficiency virus (SIVsm) infection of cynomolgus monkeys: effects on follicular dendritic cells in lymphoid tissue. 149 52

The incidence of lymphomas is unusually high in human immunodeficiency virus (HIV)-infected patients. Because cytotoxic T lymphocytes (CTL) represent a major mechanism of the antitumoral immune response in immunocompetent individuals, we asked whether intratumoral activation of CTL was impaired in acquired immune deficiency syndrome (AIDS) lymphomas. Immunohistochemical experiments showed that in AIDS lymphomas intratumoral CD8-positive T lymphocytes accumulated and expressed the TIA-1 antigen, a marker of cytotoxic cells. Flow cytometry studies and in situ hybridization of lymphomatous tissue confirmed the differentiation of CD8-positive cells in cytotoxic cells and their activation, as assessed by their expression of CD38 and human leukocyte antigen (HLA) DR markers as well as the perforin and granzyme B genes, which code for two molecules involved in target cell killing. On average, perforin-producing cells were as numerous in AIDS lymphomas (5,647 +/- 2,655 cells/cm2) as in lymphomas from immunocompetent individuals (3,294 +/- 1,544 cells/cm2). The density of activated CD8-positive cells in the 22 AIDS lymphomas tested was not correlated with peripheral CD4-positive cell counts. These results suggest that in AIDS lymphomas the steps of differentiation and activation of cytotoxic CD8-positive cells are not altered by immune deficiency and that they can take place through pathways relatively independent of CD4-positive T lymphocytes. Thus, other mechanisms of immune deficiency should account for the increased frequency of lymphomas in patients with AIDS.
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PMID:Intratumoral activation of CD8-positive cytotoxic lymphocytes in acquired immunodeficiency syndrome lymphomas. 789 Feb 79

Cytotoxic T lymphocytes (CTLs) and natural killers (NK) cells provide immune surveillance against viruses and neoplasms, and play a central role in the pathogenesis of autoimmune disease, AIDS and graft rejection. Thus, it is important to understand the precise molecular mechanism(s) whereby cytotoxic lymphocytes destroy susceptible target cells. Granule-mediated cytotoxicity requires a combination of both perforin and granzyme B. Perforin polymerizes to form transmembrane channels and presumably allows granzyme B access to target cell substrates, which until recently, were unknown. One clue to the identity of the physiological substrate(s) activated by granzyme B comes from its unusual specificity for cleaving synthetic substrates after aspartate residues. Members of the ICE/CED-3 family of cysteine proteases are prime candidates as they are important apoptotic effectors and are expressed as zymogens, which can be processed to form active heterodimeric enzymes after cleavage at specific aspartate residues. Previous studies have shown that granzyme B proteolytically activates the cell death effector Yama/CPP32/apopain (referred to here as Yama). Here we report that granzyme B also activates ICE-LAP3/Mch3/CMH-1 (referred to here as ICE-LAP3), which, along with Yama and Mch2, forms a subset of the ICE/CED-3 family of cysteine proteases most closely related to the Caenorhabditis elegans cell death gene, CED-3. Importantly, Jurkat T cells incubated with granzyme B and a sublytic concentration of perforin undergo apoptosis, which is preceded by the activation of endogenous ICE-LAP3. Thus, we propose that granzyme B mediates apoptosis by directly engaging the target cell's death effector machinery, which is probably composed of an arsenal of intracellular, CED-3-like cysteine proteases.
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PMID:Cytotoxic T-cell-derived granzyme B activates the apoptotic protease ICE-LAP3. 880 7

Anaplastic large cell lymphoma (ALCL) is composed of large, frequently bizarre, cells of T- or null-cell phenotype that show a preferential sinusoidal growth pattern and consistent CD30 positivity. Whether these tumors represent a single entity or several, and what the exact cell origin, is controversial. Recently, granzyme B, a cytotoxic granule component, was reported in a small percentage of ALCL, suggesting that some cases may originate from cytotoxic lymphocytes. To further investigate this possibility, we performed an immunohistochemical study of 33 ALCLs of T- and null-cell type, using monoclonal antibodies to cytotoxic cell-associated antigens, including CD8, CD56, CD57, and the cytotoxic granular proteins perforin and TIA-1. In addition, CD4 expression was also evaluated. ALCL cases included 27 classical systemic forms and variants, 3 primary cutaneous (PC) forms, and 3 acquired immunodeficiency syndrome-associated forms. Cytotoxic antigen expression was also studied in 51 cases of Hodgkin's disease (HD) and 17 large B-cell lymphomas (LBCLs) with anaplastic cytomorphology and/ or CD30 positivity. We found that 76% of ALCLs, representing all subtypes except the PC forms, expressed either TIA-1, perforin, or both proteins. Expression of TIA-1 and perforin were highly correlated (P < .001). On the basis of their immunophenotypic profiles, several subtypes of cytotoxic antigen positive and negative ALCL could be recognized. Fifty-five percent of ALCLs (18 of 33) displayed an immunophenotypic profile consistent with cytotoxic T cells. Six cases expressed cytotoxic granular proteins in the absence of lineage specific markers, and one case expressed both T-cell- and natural killer cell-like markers. These 7 cases (21%) were placed into a phenotypic category of cytotoxic lymphocytes of unspecified subtype. Twenty-four percent (8 cases) of ALCLs were cytotoxic granule protein negative. All but one of these displayed a T-cell phenotype. Cytotoxic granule protein expression did not correlate with the presence of the NPM-ALK fusion transcript. Only 10% of the 51 HD cases were found to be TIA-1+, and none expressed perforin. Cytotoxic antigen expression was absent in LBCL. The expression of cytotoxic granule proteins in the majority of ALCL implies a cytotoxic lymphocyte phenotype and suggests that most cases originate from lymphocytes with cytotoxic potential. Furthermore, the demonstration of cytotoxic cell related proteins may be a useful addition to the current panel of antibodies used to distinguish ALCL, HD, and anaplastic LBCL.
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PMID:Cytotoxic cell antigen expression in anaplastic large cell lymphomas of T- and null-cell type and Hodgkin's disease: evidence for distinct cellular origin. 902 30

During HIV infection the architecture of secondary lymphoid tissues is severely disrupted. In particular the germinal centers, which play a key role in the orchestration of the secondary immune response, undergo gross phenotypic alterations, leading to a complete destruction of the germinal center microenvironment. The precise mechanisms responsible for the lymphoid tissue destruction in HIV infection are still unknown. However, the large influx of CD8+ T lymphocytes suggests an important role for T cell-mediated cytotoxicity. To establish whether the infiltrating CD8+ T lymphocytes are killing competent, we investigated the expression of granzyme B, which is known to be present in the cytotoxic granules of NK cells and "activated" CTLs with cytolytic potential. We observed a 20-fold increase in the percentage of granzyme B-expressing CD8+ T cells in both the germinal center and the interfollicular areas in HIV patients relative to HIV-negative controls. This increase was present in patients with early-stage disease (i.e., absolute CD4+ T cell count > 500/microliters) as well as in patients with intermediate and late-stage disease. Thus, from relatively early stages of HIV infection onward large numbers of killing competent T lymphocytes are present in the lymphoid tissues, a finding that supports the notion that CTL act as mediators of destruction of immune function during HIV infection.
AIDS Res Hum Retroviruses 1997 Feb 10
PMID:Expression of granzyme B by cytotoxic T lymphocytes in the lymph nodes of HIV-infected patients. 911 9

Lymphoid tissues are the focus of critical events in HIV pathogenesis. Persistent and high levels of virus production, extensive trapping of virus particles in germinal centers, and progressive degenerative changes in lymph node architecture are characteristics of progressive HIV-1 infection. Infiltrates of granzyme B- and TIA-expressing CD8+ "cytotoxic" T lymphocytes (CTLs) precede involution of germinal centers in humans who develop AIDS. Similar to humans, HIV-1 infection in chimpanzees is active and persistent. However, in contrast to humans, they remain relatively resistant to AIDS. Lymph node biopsies from chimpanzees infected with HIV-1 or a related chimpanzee lentivirus were studied for the level and pattern of virus expression, changes in lymphoid architecture, CD8+ T cell infiltrates and the presence or absence of CTL markers. In stark contrast to HIV-1-infected humans, lymph nodes from infected chimpanzees had little virus deposition in germinal centers and a paucity of virus-expressing cells. Although some of the lymph nodes examined from infected animals had moderate follicular hyperplasia with infiltrating CD8+ T cells, none had evidence of follicular fragmentation. Most importantly, in marked contrast to infected humans, CD8+ T cells infiltrating the germinal center were negative for the CTL marker granzyme B. This evidence suggests that the infiltration of CD8+ CTLs into the germinal centers of lymph nodes may be a key determinant in AIDS pathogenesis.
AIDS Res Hum Retroviruses 1999 Mar 01
PMID:The relative resistance of HIV type 1-infected chimpanzees to AIDS correlates with the maintenance of follicular architecture and the absence of infiltration by CD8+ cytotoxic T lymphocytes. 1008 20

Granzymes are a family of serine proteinases commonly found in the granules of CD8+ T cells. In HIV infection, CD8+ cells show cytotoxic and noncytotoxic antiviral activities. The latter is mediated, at least in part, by a secreted CD8+ cell antiviral factor, CAF. Because of the antiviral nature of CD8+ cells, we examined the potential anti-HIV activity of free granzymes that can be found in CD8+ cell culture fluids. Pretreatment of CD4+ T cells with granzyme A or granzyme B had no effect on their susceptibility to infection with HIV, nor did incubation of the granzymes with HIV virions alter their infectivity. Continuous culture of acutely infected CD4+ T cells with granzyme A or B showed no effect on cell viability or the replication of HIV. The findings of this study suggest that free granzymes do not control HIV infection and spread in CD4+ T cells.
AIDS Res Hum Retroviruses 2000 Mar 01
PMID:HIV virions and HIV infection in vitro are unaffected by human granzymes A and B. 1071 74

Lymph nodes constitute the major site of HIV replication and of immunological response to HIV. To study the role of cytotoxic and mitotic active CD8(+) lymphocytes in lymph nodes during HIV infection we examined 28 formalin-fixed, paraffin-embedded lymph nodes sampled from 1984 to 1986 from 21 HIV-seropositive patients and seven HIV-negative patients. Eleven of the HIV-positive patients died within 78 months of biopsy time and 10 patients were alive on July 1, 1998. Double immunohistochemical staining procedures were developed to identify CD8(+) cells expressing CD45R0, granzyme B, and Ki-67. A stereological method was used to count the different cell types in the lymph nodes. There were no significant differences in the total cell (nucleated) and CD3(+) cell concentrations between the three groups. However, there were significantly higher concentrations of CD3(+)CD8(+), CD8(+)CD45R0(+), and CD8(+)Ki-67(+) lymphocytes in the HIV patients compared with the control group. Furthermore, there was a tendency for the HIV-deceased group to have lower levels of CD8(+)granzyme B(+) and CD8(+)Ki-67(+) lymphocyte concentrations compared with the HIV-alive group. Three HIV patients, who progressed to death within 49 months of biopsy time, were among the patients with the lowest concentrations of CD8(+)granzyme B(+) and CD8(+)Ki-67(+) lymphocytes. This finding allowed us to conclude that CD8(+) lymphocytes expressing high levels of CD45R0, granzyme B, and Ki-67 in lymph nodes of HIV patients are not related to increased mortality, whereas low concentrations of CD8(+) granzyme B(+) and CD8(+)Ki-67(+) lymphocytes may be associated with poor prognosis.
AIDS Res Hum Retroviruses 2001 Mar 01
PMID:High levels of CD8-positive lymphocytes expressing CD45R0, granzyme B, and Ki-67 in lymph nodes of HIV-infected individuals are not associated with increased mortality. 1124 16

Natural killer (NK) cells in rhesus macaques have been variably defined as CD3- CD16+ or CD3- CD8+, although only limited efforts have been made to validate these definitions rigorously. To better understand the role of NK cells in macaque disease models, we undertook a multiparameter analysis of macaque NK cells employing four-colour flow cytometry and a panel of lineage-specific and non-lineage-specific lymphocyte markers. Using this approach, we identified two distinct populations of candidate NK cells: a major CD8bright CD16+ population and a minor CD8bright CD16- population. Further analysis of the major and minor NK cell populations revealed the expression of multiple markers characteristic of NK cells, including CD2, CD7, CD16, CD161, NKG2A and granzyme B. In addition, a CD56+ subset of cells within the minor rhesus NK population was identified which expressed chemokine and lymph node homing receptors similar to those expressed by the CD56bright NK cell population identified in humans. Cytolytic assays confirmed that the phenotypically defined rhesus NK cells lysed NK-susceptible target cells. Our observations support the existence of several distinct subpopulations of rhesus macaque NK cells, which have significant phenotypic and functional similarities to their human counterparts. These improved immunophenotypic definitions of macaque NK cells should facilitate future analysis of innate immune responses in rhesus macaques and the role of NK cells in AIDS pathogenesis in Simian immunodeficiency virus (SIV)-infected macaques.
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PMID:Delineation of multiple subpopulations of natural killer cells in rhesus macaques. 1588 26

The impaired functional activity of cytotoxic T lymphocytes and natural killer cells during HIV-1 infection has recently been attributed to decreased intracellular levels of perforin and granzyme B. In sera from individuals chronically infected with HIV-1 we report increased levels of extracellular perforin compared with uninfected individuals. Increased perforin was also observed during experimental SIV/SHIV infection. The combination of reduced intracellular perforin levels and an increased serum level indicates that HIV infection induces aberrant perforin secretion.
AIDS 2006 Jan 02
PMID:Elevated levels of serum perforin in chronic HIV-1 and acute SIV/SHIV infection. 1632 31


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