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PubMed1994

Evolving understanding of the immunopathogenesis of HIV.

Understanding of the immunopathogenesis of HIV infection is becoming more advanced as the activity of HIV infection in lymph nodes is appreciated and as improved virological measures permit more accurate quantitation of viral burden in patients at all stages of HIV disease. Although CD4+ cell counts remain important prognostic indicators, their role as a surrogate for direct antiviral activity has been questioned and increasing focus has been placed on more direct quantitative viral measures that are now available. After an initial explosive burst of viral replication during acute seroconversion that is downregulated by the immune system, these newer markers have revealed that viral replication is ongoing during the so-called "clinically latent" period of HIV infection. One of the most active sites of viral replication during this asymptomatic period is in lymphoid tissues. Over time, however, immunological control of HIV wanes, the site of replication shifts from the lymph nodes to other lymphoid organs, and disease progression ensues. The role of viral diversity in late-stage HIV disease is now well established, yet its role in pathogenesis and establishment of viruses resistant to antiviral agents is not fully established. Increased understanding of how HIV causes immune dysfunction may help us control direct and indirect (opportunistic) complications of HIV infection.

CD4 Lymphocyte Count↗
PubMed1995

Frequency of provirus-bearing CD4+ cells in HIV type 1 infection correlates with extent of in vitro apoptosis of CD8+ but not of CD4+ cells.

Lymphocytes from HIV-1-infected subjects undergo massive apoptosis when cultured in vitro, and this phenomenon might reflect pathogenetic mechanisms leading to immune dysfunction in vivo. However, (1) lymphocyte death is not restricted to CD4+ cells but seems to involve predominantly CD8+ cells, and (2) the same phenomenon occurs in other viral infections. Furthermore, it is not known whether a relationship exists between the HIV-1 burden and this type of cell death. In this work we sought to determine whether the HIV-1 provirus load correlates with the propensity to apoptosis of CD4+ and CD8+ cells. We studied 10 HIV-1-infected patients with CD4+ cell counts above 500/mm3 and free of concomitant infections. We correlated the frequency of HIV-1-infected CD4+ cells with the extent of culture-induced apoptosis as well as with the phenotype of the apoptotic lymphocytes. We found that the magnitude of apoptosis correlated with the frequency of HIV-1-infected CD4+ cells (p = 0.0007), and that increasing viral load and apoptosis were associated with a shift to the selective death of CD8+ cells. Our data support the view that, in addition to CD4+ cell killing, another immunopathogenic effect of HIV might be that of priming CD8+ cells to apoptosis. In vivo, this could eventually lead to the exhaustion of the cytotoxic T cell compartment.

Adult↗
PubMed1996

Differential production of interleukin 10 during human immunodeficiency virus infection.

Interleukin 10, a product of T and B cells and monocytes, displays many Th2-like properties through inhibition of Th1 cell functions. Interleukin 10 is thought to play a major role in the immune dysfunction seen in HIV-infected individuals. In this study, we evaluated in detail the production of IL-10 during HIV infection. Although the constitutive production of IL-10 did not differ in PBMCs from healthy donors and HIV-infected individuals, IL-10 was differentially produced in response to polyclonal activators. The overall plasma IL-10 levels were similar in 32 controls and 67 patients at different stages of the disease and receiving different antiretroviral drugs. However, patients with low CD4 T cell count (< 200/mm3) secreted approximately three-fold more IL-10 than did patients with high CD4 T cell count (> 500/mm3). Competitive/quantitative PCR revealed similar levels of mRNA expression in PBMCs from controls and HIV-infected individuals. In vitro HIV infection rapidly and transiently induced IL-10 production in PBMCs and monocytes, and the low level of endogenously secreted IL-10 failed to inhibit HIV replication in acutely infected monocytes. On the other hand, HIV infection of selected CD4+ T cell clones generated in a Th1- or Th2-like environment, differentially up-regulated IL-10 production, with significantly higher production by Th2 clones. Together, our data indicate that IL-10 production is more complex than previously thought, and may depend on several factors such as producer cells, nature of the stimuli, as well as viral isolates.

CD4 Lymphocyte Count↗
PubMed1997

Interleukin 6 and AIDS-associated Kaposi's sarcoma: a nested case control study within the Multicenter AIDS Cohort Study.

Since the beginning of the AIDS epidemic, there has been considerable research on the etiology of Kaposi's sarcoma (KS) among HIV-infected individuals. A number of studies have confirmed that HIV or HIV-encoded products can interact with human cells to induce the production of cytokines, including interleukin 6 (IL-6). In vitro observations have indicated that AIDS-KS cells can produce significant levels of IL-6 and also respond to this cytokine. Preliminary data suggested that IL-6 may be elevated among HIV-infected individuals that subsequently develop AIDS-KS. The objective of this study was to determine if elevated levels of IL-6 are associated with an increased incidence of AIDS-KS compared to other AIDS-defining illnesses such as opportunistic infections (OIs). Serum IL-6 levels were determined by ELISA in frozen sera collected from participants in the Multicenter AIDS Cohort Study (MACS) at 6 months prior to AIDS diagnosis, in 73 cases (AIDS-KS), and 152 controls (OI). Elevated IL-6 levels were more prevalent among men with AIDS-OI than those with AIDS-KS: crude odds ratio (OR), 0.4 (95% CI, 0.2-0.9). Models of multivariate logistic regression were used to study potential confounders. Sexual behavior variables did not seem to confound the association between IL-6 and AIDS-KS. The higher prevalence of IL-6 among controls could be explained by the association of higher levels of IL-6 with lower levels of CD4 T cell number. IL-6 may be a marker of severe immune dysfunction among HIV-infected individuals.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Disturbed secretory capacity for macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta in progressive HIV infection.

The protective role of beta-chemokines in HIV infection and disease remains controversial. Contradictory findings have been reported possibly as the result of different beta-chemokine detection methods. To test this, peripheral blood lymphocytes from treatment-naive HIV patients, patients on highly active antiretroviral therapy (HAART), and uninfected controls were assessed for intracellular beta-chemokine levels in comparison with levels of beta-chemokine secretion in culture supernatants. HIV patients had significantly higher intracellular levels of macrophages inflammatory protein (MIP)-1 alpha and MIP-1 beta than uninfected control subjects. In contrast, MIP-1 alpha and MIP-1 beta supernatant levels were significantly lower in HIV patients than in controls. Interestingly, both intracellular and supernatant levels of RANTES (regulated on activation, normal T cell expressed and secreted) were significantly increased in HIV patients. Prolonged (> 3 years) administration of HAART in HIV patients normalized the intracellular levels of MIP-1 beta and RANTES and restored the decreased supernatant levels of MIP-1 alpha and MIP-1 beta to levels observed among controls. Significant direct correlations observed between the intracellular and the supernatant levels of beta-chemokines in controls were lost in treatment-naive (except MIP-1 beta) and HAART-treated patients (except RANTES after 3 years of HAART). These data indicate that lymphocytes of HIV patients display a disrupted capacity to secrete the beta-chemokines MIP-1 alpha and MIP-1 beta, which may constitute a mechanism of immune dysfunction in progressive HIV infection. Furthermore, we demonstrated that the detection of beta-chemokines in HIV patients by different methods may indeed result in contradictory findings.

Antiretroviral Therapy, Highly Active↗
PubMed1988

In vitro functional characterization of SAG-3--a naturally occurring monoclonal antibody in NZB mice: specificity toward functional T cell subsets.

Natural thymocytotoxic autoantibodies (NTA) have been suggested to contribute to the T cell mediated immune dysfunction prevalent in NZB mice. However, direct studies to confirm these suggestions have been difficult to perform due to the absence of large amounts of pure NTA. To overcome this problem, we generated a naturally occurring monoclonal antibody from an NZB mouse which possesses the serological characteristics of serum-NTA. Herein, we report the in vitro functional characteristics of this monoclonal antibody designated SAG-3. In vitro treatment of spleen and lymph node cells from BALB/c mice with SAG-3 and complement eliminated most of the proliferative response to Con-A and moderately reduced the response of these cells to PHA-P and PWM. Complement mediated cytolysis of SAG-3 reactive cells significantly reduced the capacity of unprimed lymph node cells to generate primary CTL responses in vitro against allogeneic cells. However, only a partial decrease in CTL activity was observed when primed secondary CTL effector cells were treated, due primarily to the depletion of CTL's specific towards MHC class I antigens. Furthermore, a moderate reduction in antigen-specific helper T cell function was observed. Pretreatment of responder cells with SAG-3 + C' did not appear to reduce the proliferative MLR response to a wide range of stimulator cells. In addition, contrary to previous reports on serum-NTA, SAG-3 appears not to be reactive against Con-A induced suppressor T cells. Finally, by FACS analysis SAG-3+ thymocytes constitute an overlapping population of Lyt-2+ and L3T4+ thymocytes. These findings are discussed in comparison to previous reports on NTA.

Animals↗
PubMed1999

Correlation of clinical parameters and immunological function with human immunodeficiency virus plasma viremia in children.

Studies of immune function in human immunodeficiency virus (HIV)-infected children are important, because functional abnormalities can precede CD4+ T-cell loss and are associated with the development of opportunistic and bacterial infections. We sought to correlate clinical parameters and immunological function with HIV RNA plasma levels in 20 children. HIV RNA levels were measured by a polymerase chain reaction assay. We analyzed T-cell responses to mitogens (phytohemagglutinin, concanavalin A, and pokeweed [PWM]) and antigens (tetanus toxoid and Candida albicans); T-cell suppressor activity; and humoral immunity to Haemophilus influenzae, hepatitis B, tetanus, and diphtheria vaccines. The median age of the children was 6 years. Eight children had HIV RNA levels less than 200 to 9621 copies per milliliter (group I). Four children had 37,970 to 82,630 copies per milliliter (group II). Eight children had 102,100 to 191,200 copies per milliliter (group III). There were no differences in the HIV-related complications between group I and II children. Group I/II children had significantly higher CD4+ T-cell counts (P = 0.02), less symptomatic HIV disease (P = 0.005), and more detectable protective vaccine immunity (P = 0.014) compared with group III children. Responses to mitogens were conserved in most children. Group I children tended to have higher responses to tetanus toxoid than group II children and significantly higher responses than group III children (P = 0.01). Group I had significantly higher responses to C. albicans than groups II (P = 0.016) and III (P = 0.001). Group I/II children tended to have lower suppressor activity compared with group III children (median, 0 vs 64%). We demonstrated that humoral and cellular immune dysfunction exists at all stages of disease in HIV-infected children but was most severe in children with greater than or equal to 100,000 HIV RNA copies per milliliter. Function was the most intact in children with less than 10,000 copies per milliliter.

Adolescent↗
PubMed1984

Acquired immune deficiency syndrome: postmortem findings.

The autopsies of 13 male homosexuals with acquired immune deficiency syndrome (AIDS) were reviewed. All patients had laboratory evidence of cellular immune dysfunction. The most common diagnoses made were disseminated cytomegalovirus infection in 12 patients and Kaposi's sarcoma in 10. All patients infected with cytomegalovirus had pulmonary compromise. The adrenal glands and gastrointestinal tract also were involved often by cytomegalovirus. Cytomegalovirus infection of organs uncommonly affected such as heart, meninges, cerebrum, and peripheral nerves was documented in two patients. Skin most frequently was involved by Kaposi's sarcoma, followed by gastrointestinal tract and lymph nodes. Two patients had visceral and/or nodal Kaposi's sarcoma with no skin compromise. Other important diagnoses were Pneumocystis carinii pneumonia, cryptosporidiosis, fungal infections, toxoplasmosis, and brain lymphoma. The cause of death was due to one or more infections in most patients. Kaposi's sarcoma did not contribute substantially to the cause of death, except in one patient with massive multifocal and multiorgan involvement.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Non-Hodgkin malignant lymphomas and peripheral neuropathies--13 cases.

Non-Hodgkin's malignant lymphomas (NHML) are malignant lymphoid proliferations which may be of B or T cell type. Thirteen observations of an association between peripheral neuropathy and B type NHML are reported. None of the cases had evidence of meningeal propagation or neurotoxicity from chemotherapy. The NHML were classified according to the Working Formulation and Kiel classifications. The various mechanisms of peripheral neuropathy in these cases were split into four broad groups. Group I consisted of four cases in which the peripheral nerve lesions were directly linked to a propagation of malignant cells into the peripheral nervous system; this was revealed by autopsy and/or nerve biopsy. Malignant B cell proliferation was demonstrated in three out of four of these cases by immunolabelling of the infiltrates. Group II included three patients whose serum contained a monoclonal immunoglobulin (IgM) with antimyelin activity, and two who had pathological IgM deposits in endoneurial connective tissue. Group III comprised two cases. The immune dysfunction of the NHML was responsible for a Guillain-Barré syndrome in one, and for a chronic inflammatory demyelinating polyneuropathy in the other. Group IV included two patients in whom the mechanism of the peripheral neuropathy, although almost certainly directly related to the NHML, could not be determined beyond doubt. The peripheral neuropathy might have been a result of a paraneoplasic process or, possibly, an undetected lymphomatous invasion of nervous tissue. All these cases of clinically diverse peripheral neuropathy, which either occurred before the discovery of the haemopathy or arose as complications of it, are discussed along with similar observations reported in the literature. Immunolabelling of lymphomatous proliferations and nerves is now of considerable value for classifying and indicating the exact aetiology of the peripheral neuropathy. It can also detect pathogenic consequences of any associated monoclonal dysglobulinemia. In any event, a direct link between the peripheral neuropathy and NHML represents an indication for intensification of specific chemotherapy, which in some of our patients led to significant regression of the peripheral neuropathy. Nonetheless, in some cases, the link between peripheral neuropathy and NHML could not be established with certainty. Long-term follow-up is essential in such cases. The present results show the importance of a case by case study of patients with NHML and peripheral neuropathy.

Aged↗
PubMed1989

Diet-induced DNA damage and altered nucleotide metabolism in lymphocytes from methyl-donor-deficient rats.

Tumor induction with chronic feeding of methyl-donor-deficient diets has been well established; however, the biochemical and molecular mechanisms which predipose to tumorigenesis in this model are still not well understood. The purpose of the present investigation was to assess DNA damage and altered nucleotide metabolism in lymphocytes from Fischer 344 rats fed one of four semi-purified diets: (i) deficient in methionine and choline; (ii) deficient in folic acid; (iii) deficient in methionine, choline and folic acid; or (iv) a supplemented control diet. The accumulation of DNA-strand breaks, as assessed by DNA unwinding in alkali, was increased in lymphocytes from both the methionine/choline-deficient and folate-deficient groups, but was most severe in the group deficient in all three methyl donors. Lymphocyte DNA damage was consistently associated with alterations in folate-dependent thymidylate synthesis, and a decrease in intracellular levels of the DNA-repair-associated pyridine nucleotide, nicotinamide adenine dinucleotide. In the liver, a synergistic lipotropic interaction between folate deficiency and methionine/choline deficiency was observed, confirming the metabolic inter-relationship between these nutrients. Taken together, the results suggest that folate deficiency interacts with methionine/choline deficiency to potentiate symptoms of methyl-donor deficiency and that alterations in folate-dependent thymidylate synthesis are related to DNA damage in lymphocytes. These metabolic aberrations may contribute to immune dysfunction with chronic feeding of methyl-donor-deficient diets.

Animals↗
PubMed1995

Construction of YAC contigs at human chromosome 11q22.3-q23.1 region covering the Ataxia telangiectasia locus.

Ataxia telangiectasia (AT) is an autosomal recessive disease of unknown etiology associated with cerebellar ataxia, telangiectasia, immune dysfunction, higher cancer risk, genomic instability and hypersensitivity to ionizing radiation. The major AT loci, AT-A and AT-C, are shown to be closely linked at chromosome 11q22-q23. The most recent genetic linkage mapping and linkage disequilibrium analysis have localized the major AT loci to a sequence of approximately 850 kb between the markers D11S1819 and D11S1818. The isolation of yeast artificial chromosomes spanning the AT region is an essential step to identify the gene or genes responsible for the mutation(s). We isolated a total of 20 YAC clones from three independent YAC libraries, using sequence tagged sites mapped in the AT region as primers for PCR-based YAC screening. The PCR assay for the presence or absence of 16 different DNA markers allowed us to construct and to order four YAC contigs at the AT region. One of the contigs which consists of the 10 YAC clones, covers about 2 Mb of DNA at the boundary between Giemsa-positive band 11q22.3 and Giemsa-negative band 11q23.1 and includes the entire region of the major AT locus between D11S1819 and D11S1818. Thus, the YAC contigs will facilitate the positional cloning approach for searching transcribed sequences from the defined genomic region.

Ataxia Telangiectasia↗
PubMed2001

Associations of subclinical cardiovascular disease with frailty.

BACKGROUND: Frail health in old age has been conceptualized as a loss of physiologic reserve associated with loss of lean mass, neuroendocrine dysregulation, and immune dysfunction. Little work has been done to define frailty and describe the underlying pathophysiology. METHODS: Frailty status was defined in participants of the Cardiovascular Health Study (CHS), a cohort of 5,201 community-dwelling older adults, based on the presence of three out of five clinical criteria. The five criteria included self-reported weight loss, low grip strength, low energy, slow gait speed, and low physical activity. We examined the spectrum of clinical and subclinical cardiovascular disease in those who were frail (3/5 criteria) or of intermediate frailty status (1 or 2/5 criteria), compared to those who were not frail (0/5). We hypothesized that the severity of frailty would be related to a higher prevalence of reported cardiovascular disease (CVD), as well as to a greater extent of CVD, measured by noninvasive testing. RESULTS: Of 4,735 eligible participants, 2,289 (48%) were not frail, 299 (6%) were frail, and 2.147 (45%) were of intermediate frailty status. Those who were frail were older (77.2 yrs) compared to those who were not frail (71.5 yrs) or intermediate (73.4 yrs) (p < .001). Frailty status was associated with clinical CVD and most strongly with congestive heart failure (odds ratio [OR] = 7.51 (95% confidence interval [CI] = 4.66-12.12). In those without a history of a CVD event (n = 1.259), frailty was associated with many noninvasive measures of CVD. Those with carotid stenosis >75% (adjusted OR = 3.41), ankle-arm index <0.8 (adjusted OR = 3.17) or 0.8-0.9 (adjusted OR = 2.01), major electrocardiography (ECG) abnormalities (adjusted OR = 1.58), greater left ventricular (LV) mass by echocardiography (adjusted OR = 1.16), and higher degree of infarct-like lesions in the brain (adjusted OR = 1.71), were more likely to be frail compared to those who were not frail. The overall associations of each of these noninvasive measures of CVD with frailty level were significant (all p < .05). CONCLUSIONS: Cardiovascular disease was associated with an increased likelihood of frail health. In those with no history of CVD, the extent of underlying cardiovascular disease measured by carotid ultrasound and ankle-arm index, LV hypertrophy by ECG and echocardiography, was related to frailty. Infarct-like lesions in the brain on magnet resonance imaging were related to frailty as well.

Black or African American↗
PubMedDate not supplied

Phenotypic and functional studies of leukocytes in human endometrium and endometriosis.

The aetiology of endometriosis, a common and disabling disorder, is presently unknown, although immune dysfunction could allow ectopic endometrial fragments to survive outside the uterine cavity. These studies investigate the relationship between leukocyte populations, steroid hormone receptor expression, proliferative activity, bcl-2 expression and apoptosis in eutopic and ectopic endometrium from women with endometriosis or adenomyosis at different phases of the menstrual cycle. Significantly increased oestrogen receptor expression, bcl-2 expression and numbers of CD8+ leukocytes were found in ectopic compared with eutopic endometrium in endometriosis, and CD56+ endometrial granulated lymphocytes (eGLs) were significantly reduced in ectopic endometrium. Apoptotic cells were rarely found in control and subject endometria. In contrast with endometriosis, adenomyotic lesions showed identical steroid hormone receptor expression, proliferative activity, bcl-2 expression and leukocyte subpopulations to eutopic endometrium, indicating different aetiologies for these disorders. The unusual CD56+ CD16- eGLs present in large numbers in late secretory phase eutopic endometrium were highly purified (>98%) by immunomagnetic separation. Except for a negligible cytotoxic activity of eGLs from early proliferative samples, cytotoxic activity of eGLs from non-pregnant endometrium during the menstrual cycle was comparable with those in peripheral blood, predominantly CD56+ CD16+ natural killer cells. eGLs from non-pregnant endometrium and early pregnancy showed a variable proliferative response to 5 and 100 U/ml interleukin-2 over 48-h and 120-h time courses. eGLs are evidently functionally important in the eutopic endometrium. Their absence in endometriotic lesions together with increased CD+8 T-cell numbers and increased oestrogen receptor and bcl-2 expression may have significant effects on the development and progression of endometriosis.

Antigens, CD↗
PubMed1986

Association of symptomatic human infection with Toxoplasma gondii with imbalance of monocytes and antigen-specific T cell subsets.

During recent symptomatic toxoplasmosis, alterations in quantity and function of mononuclear cells in peripheral blood were observed. Flow cytofluorometric analysis and differential leukocyte counts revealed increased absolute numbers of T8+ cells, Leu 7+ (natural killer/killer) cells, and monocytes. T4+ cells and HLA-DR+ cells were not significantly changed. T4/T8 cell ratios were reversed in symptomatic toxoplasmosis (0.7 +/- 0.3) and normal in chronic infection (1.7 +/- 0.5). Toxoplasma antigen induced higher numbers of T8+ and TQ1+ cells in four T cell lines from two individuals with symptomatic infection than in five T cell lines from three individuals with asymptomatic infection. Eight cloned T cell lines produced gamma interferon in an antigen-specific fashion and in higher amounts when they originated from an asymptomatic subject than from a symptomatic subject. These results indicate that marked alterations in properties of immunoregulatory cells are characteristic of recent symptomatic toxoplasmosis. The transient immune dysfunction may be a major part of the observed disease and/or a feature of successful parasitism.

Acute Disease↗
PubMed1994

Infection of human bone marrow stromal cells by hepatitis B virus: implications for viral persistence and the suppression of hematopoiesis.

Suspension cultures of bone marrow cells (BMC) were challenged with hepatitis B virus (HBV) to study interactions between the virus and the nonadherent and adherent BMC populations. Virus-challenged BMC developed an adherent stromal layer that differed in cellular composition from that of mock-infected cultures, showing a threefold increase in cells of the monocyte-macrophage lineage with an accompanying decrease in cells of the granulocytic lineage. Both viral envelope hepatitis B surface and core antigen expression was detected in adherent and nonadherent cell populations up to 10 days after virus challenge, which decreased thereafter. HBV DNA was still detectable in adherent cells 3 weeks after virus challenge, as shown by polymerase chain reaction analysis. These data indicate that HBV can infect not only bone marrow colony-forming cells but also the stromal cell populations involved with the regulation of hematopoiesis in vivo. Such virus-cell interactions could contribute to the immune dysfunction and bone marrow failure occasionally reported for patients with HBV infection as well as acting as an important site for HBV latency and persistence.

Bone Marrow↗
PubMed1996

Human immunodeficiency virus type 1 (HIV-1)--and Epstein-Barr virus--specific cytotoxic T lymphocyte precursors exhibit different kinetics in HIV-1--infected persons.

The frequencies of human immunodeficiency virus type 1 (HIV-1) Gag- and Epstein-Barr virus (EBV)-specific cytotoxic T lymphocyte precursors (CTLp) were studied longitudinally in peripheral blood mononuclear cells from 9 HIV-1-infected persons. By antigen-specific stimulation, HIV-1 Gag-specific CTLp were detected in vitro throughout the course of HIV-1 infection, even after the onset of overt disease. In 4 patients, however, HIV-1 Gag-specific CTLp frequencies declined over time in the presence of maintained EBV-specific CTLp. This decline was correlated with decreasing CD4 (r = .38; P < .05) and CD8 (r = .75; P < .001) cell numbers. The maintenance of EBV-specific CTLp in patients with low CD4 cell numbers indicated that EBV-specific CTL-mediated immunity may remain longer unaffected by HIV-1-induced immune dysfunction. Consistent with this observation, the growth of EBV-specific CTL could be supported in vitro by EBV-infected lymphoblastoid B cell lines, independent of both CD4 cells and exogenous cytokines.

Acquired Immunodeficiency Syndrome↗
PubMed1990

CD4 and CD8 T cells from SIV-infected macaques have defective signaling responses after perturbation of either CD3 or CD2 receptors.

Single-cell clones, designated E11S, C11R, and A1S, were obtained from the HuT-78 T cell line persistently infected with an isolate of Simian immunodeficiency virus (SIV), SIV/Mne. The infected clones, unlike uncloned uninfected HuT-78 cells, no longer expressed the CD4 marker and, after their CD3 receptors were cross-linked, had dramatically reduced intracellular free calcium ([Ca2+]i) responses. In one clone, E11S, the unresponsiveness was not limited to the inositol phospholipid pathway of signaling since a reduction in CD3-mediated activation of protein tyrosine kinase-dependent phosphorylation also was evident in this SIV-infected clone. These results led us to test whether T lymphocytes from animals infected with SIV had defective [Ca2+]i responses prior to detectable changes in CD4 levels or lymphadenopathy. The [Ca2+]i responses to both CD3 mAb and CD2 mAb were 10-50% less in T cells from Walter Reed stage 2 animals than in healthy controls. This anergy was more pronounced in chronically infected animals progressing to Walter Reed stage 3/4. The responses of these animals could not be augmented even when combinations of CD3 and CD4 mAb were used. Both CD4+CD44lo T cells, which are not infected with SIV, and the CD4+CD44hi T cell subset, previously shown to be the reservoir of SIV infection in blood, had pronounced defective responses to CD3 mAb. Similarly, both CD4+ and CD8+ T cells were consistently unresponsive in chronically infected animals, again implying that an indirect mechanism, rather than SIV infection per se, may be responsible for this immune dysfunction.

Animals↗
PubMed2006

The uremic solute p-cresol decreases leukocyte transendothelial migration in vitro.

Chronic renal failure (CRF) patients display an immunodeficiency state, and uremic solutes that accumulate during CRF may be involved in this immunodeficiency. In this study, we examined whether the uremic solute para-cresol (p-cresol), at concentrations similar to those found in patients, alters leukocyte transmigration in vitro. We found that p-cresol significantly inhibited monocyte THP-1 cell line and PBMCs transmigration across IL-1beta-stimulated human umbilical vein endothelial cell (HUVEC) in a static two-compartment model. This inhibitory effect of p-cresol persisted in the presence of a physiologic concentration of human serum albumin. In order to investigate the mechanism involved, expression of endothelial chemokines, fractalkine, monocyte chemoattractant protein 1 (MCP-1) and IL-8 and membrane expression of junctional adhesion molecule A (JAM-A or JAM-1) were studied. We found that p-cresol decreased mRNA expression of the chemokine fractalkine in IL-1beta-stimulated HUVEC, without modifying mRNA expression of MCP-1 and IL-8. In addition, p-cresol decreased IL-1beta-induced expression of membrane-bound and soluble forms of fractalkine and impaired the membrane expression of JAM-A. Taken together, these results suggest that p-cresol, by impairing leukocyte transendothelial migration, plays a role in the immune dysfunction of uremic patients.

Cells, Cultured↗