UMLS:C0021051 - FACTA Search

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

In this study, we examined the potential role of the human immunodeficiency virus (HIV) tat protein in causing the hematopoietic abnormalities frequently observed in HIV-infected individuals. Recombinant tat (r-tat) protein, at concentrations up to 10 micrograms/mL, did not display any stimulatory or inhibitory effect on the survival/proliferative capacity of CD34+ hematopoietic progenitor cells, purified from normal bone marrow (BM). However, exposure of r-tat protein (at concentrations between 10 ng/mL and 10 micrograms/mL) to enriched normal BM macrophages induced the production of a factor(s) in conditioned media that inhibited the in vitro growth of CD34+ cells in liquid cultures and of immature hematopoietic progenitors (day 14 colony-forming unit-granulocyte-macrophage, burst-forming unit-erythroid, and colony-forming unit-megakaryocyte) in semisolid assays. Pre-exposure of r-tat protein with a monoclonal neutralizing anti-tat antibody completely abrogated the inhibitory activity present in BM macrophage culture supernatants. The main factor responsible for this suppressive activity was transforming growth factor-beta 1 (TGF-beta 1), as shown by the ability of a polyclonal anti-TGF-beta 1 neutralizing antibody to almost completely reverse the suppressive effect of BM macrophage supernatants on CD34+ cells. TGF-beta 1 bioassays showed that exposure of r-tat protein to BM macrophages significantly increased the levels of both active and latent forms of TGF-beta 1. These results indicate that the production of TGF-beta 1, one of the most potent negative regulator of hematopoiesis, is increased by HIV tat protein and that such increase could contribute to the derangement of the hematopoietic system in HIV-infected individuals.
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PMID:tat protein stimulates production of transforming growth factor-beta 1 by marrow macrophages: a potential mechanism for human immunodeficiency virus-1-induced hematopoietic suppression. 128 86

Parasitic infection is frequently accompanied by a downregulation in host cell-mediated immunity. Recent studies suggest that this modulation of helper T cells and effector cell function can at least in part be attributed to the action of a set of inhibitory cytokines produced by T lymphocytes as well as by a number of other cell types. The best characterized of these inhibitory lymphokines are IL-4, IL-10 and TGF-beta. Interestingly, both IL-4 and IL-10 are produced by the Th2 but not the Th1 subset of CD4+ helper cells. The former subset dominates in many situations of chronic or exacerbated parasitic infection and is thought to suppress Th1 function as a consequence of the cross-regulatory activity of these two cytokines. The latter hypothesis is supported by recent experiments demonstrating that mAb-mediated neutralization of IL-10 reverses suppressed IFN-gamma responses and/or disease susceptibility in mice with parasitic infections. In vivo neutralization of TGF-beta has also been reported to increase host resistance to parasite challenge. In addition to suppressing T-cell differentiation, function or proliferation, IL-4, IL-10 and TGF-beta each inhibit the ability of IFN-gamma to activate macrophages for killing of both intracellular and extracellular parasites. Moreover, the three cytokines are able to synergize with each other in downregulating these parasiticidal effects. Interestingly, each of the cytokines inhibits the production of reactive nitrogen oxides, an effector mechanism previously demonstrated to play a major role in parasite killing by activated macrophages. In the case of IL-10, this suppression of nitrogen oxide production appears to result from an inhibition of TNF-alpha synthesis leading to defective macrophage stimulation. While distant from parasites in their biology and phylogeny, some retroviruses also appear to induce an over-production in downregulatory cytokines which is closely associated with the onset of immunodeficiency. Thus, in an animal model involving infection of mice with LP-BM5 MuLV and in human HIV infection, Th2 (IL-10 and/or IL-4) cytokine synthesis is increased while Th1 (IFN-gamma and/or IL-2) cytokine production is suppressed. These observations suggest that cytokine-mediated cross-regulation may play a role in the pathogenesis of acquired immune deficiency disease, contributing both to the progression of retroviral infection and the increase in susceptibility to opportunistic infections and malignancy. Observations of similar cytokine cross-regulatory activities in organisms as diverse as helminths, protozoa and retroviruses predict that comparable mechanisms may operate in a wide variety of infectious diseases.
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PMID:Role of T-cell derived cytokines in the downregulation of immune responses in parasitic and retroviral infection. 135 51

The ability of the human immunodeficiency virus (HIV) to replicate in CD+ T lymphocytes and mononuclear phagocytes(MP) is strongly influenced by immunoregulatory cytokines. In the T cell system, interleukin-2 (IL-2) provides a mitogenic signal leading to both cell proliferation and virus replication. Among other HIV-inductive cytokines, only tumor necrosis factor-alpha or -beta (TNF-alpha/-beta) have been shown thus far to trigger virus expression both in T cells and MP. The mechanism of action of TNF involves the activation of the cellular transcription factor NF-kB which binds to specific consensus sequences present in the enhancer region of the HIV proviral LTR. In addition, several other cytokines (including colony stimulating factors, IL-1, IL-3, and IL-6) have demonstrated upregulatory effects on HIV production in MP, whereas nonimmune interferons (INF-alpha/-beta) have been shown to suppress HIV replication in T cells and MP by acting at different phases in the virus life cycle. Finally, cytokines such as TGF-beta, IFN-gamma, and IL-4 have demonstrated either upregulatory or suppressive effects on virus expression depending on the experimental conditions. This scenario indicates that HIV expression is under the control of a complex network of immunoregulatory cytokines, in addition to its own endogenous regulatory proteins, suggesting that new pharmacologic strategies may be aimed at either mimicking or interrupting cytokine-dependent virus expression. In this regard, a number of different physiologic and pharmacologic agents capable of interfering with cytokine-mediated events, including glucocorticoids, anti-oxidants, such as N-Acetyl-L-Cysteine (NAC), and retinoic acid (RA) have already been shown to profoundly affect HIV replication in vitro.
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PMID:The effect of cytokines and pharmacologic agents on chronic HIV infection. 154 Apr 7

Induction of lymphokine-activated killer (LAK) activity by IL-2 has been described and characterized as broadly cytolytic activity against both fresh and cultured tumors. rIL-7 in the absence of IL-2 also induces LAK activity in human cells. This activity is unique for IL-7, because it is not shared by other cytokines including IL-1, IL-4, IL-6, and TNF-alpha. IL-7 also induces either de novo or increased expression of the surface markers CD25 (Tac, IL-2R alpha-chain), CD54 (ICAM-1), Mic beta 1 (IL-2R beta-chain) and CD69 (early T cell activation Ag). IL-7-induced LAK activity is independent of IL-2 secretion, because it is not abrogated by IL-2 antisera. The LAK precursor responding to IL-7 stimulation is enriched in the null cell fraction as has been demonstrated for IL-2-induced LAK cells. TGF-beta and IL-4 interfere with generation of LAK activity by IL-7. Anti-IL-4 antiserum enhances IL-7-induced LAK activity and augments induction of surface marker expression by IL-7. This may be indirect evidence that IL-7 stimulation leads to induction of IL-4 activity. Our results describe the activation of mature lymphoid cells by IL-7. This and the previously described role of IL-7 in lymphohemopoiesis makes it a cytokine of potential therapeutic value for treatment of immunodeficiency states and possibly the immunotherapy of cancer.
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PMID:IL-7 induces human lymphokine-activated killer cell activity and is regulated by IL-4. 167 Jun 2

Plasmacytoma-bearing mice (PC-mice) develop a polyclonal B cell immunodeficiency syndrome characterized by marked impairment of: a) primary antibody responses and b) proliferative responses to B cell mitogens. The present investigations used two-color flow cytometry to examine B lymphocytes from the spleens and lymph nodes of PC-mice and found decreased surface membrane expression of surface IgM (sIgM), transferrin receptors (TfR) and IgE FcR (CD23), increased expression of class II MHC, but normal expression of B220, Mel-14, Fc gamma RII, and Fc mu R. These changes were not related to the H chain class or the amount of Ig produced by the plasmacytoma. When cultured with IL-4, B lymphocytes from PC-mice increased their expression of sIgM and class II MHC, but not of CD23. Several findings implicate transforming growth factor-beta 1 (TGF-beta 1) in the mechanism that modulates receptor expression on B lymphocytes in PC-mice: a) ascites fluid from PC-mice contains large quantities of TGF-beta 1; b) supernatants of cultured spleen cells from PC mice contain up to eightfold more TGF-beta than is found with normal spleen cells; c) cloned plasmacytoma cells produce TGF-beta in vitro; and d) the abnormal phenotype of B cells from PC-mice, i.e., decreased CD23, sIgM, and TfR, and increased class II MHC, is induced on normal B cells cultured in the presence of TGF-beta 1. Because sIgM, TfR, class II MHC, and CD23 are molecules that play fundamental roles in the activation of normal B cells, their modulation by TGF-beta 1: a) identifies molecular mechanisms that could account for some of the known immunosuppressive properties of TGF-beta 1 and b) implicates TGF-beta in the pathogenesis of the polyclonal B cell immunodeficiency that is characteristic of plasma cell tumors.
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PMID:Immune dysfunction in mice with plasmacytomas. I. Evidence that transforming growth factor-beta contributes to the altered expression of activation receptors on host B lymphocytes. 182 99

We showed that an extract (PC6) from cones of Pinus parviflora Sieb et Zucc induced the human T-cell line CEM to produce a pepsin-sensitive soluble factor(s) that could inhibit the replication of the type 1 human immunodeficiency virus (HIV-1) in CEM T cells, in U-937 histocytes, in THP-1 monocytes, and in mitogen-activated human tonsillar mononuclear cells. Indirect immunofluorescence staining and polymerase chain reaction analysis of the PC6-induced CEM cells revealed the absence of known lymphokines/cytokines except granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), transforming growth factor beta 1 (TGF-beta 1), and tumor necrosis factor alpha (TNF-alpha). However, functional studies with recombinant IL-3, TNF-alpha, and TGF-beta 1 showed that these three factors did not inhibit HIV-1 replication in CEM cells. Neutralization of the PC6-induced HIV-1-inhibiting factor(s) with commercially available neutralizing antibodies to GM-CSF and TNF-alpha also did not abrogate the anti-HIV-1 impact. Thus, the anti-HIV-1 factor induced by PC6 may be novel. Molecular sieve separation showed that the anti-HIV-1 factor(s) is smaller than 30 kDa. Affinity chromatography using a DEAE-cellulose column enriched the factor that inhibited HIV-1.
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PMID:A soluble factor induced by an extract from Pinus parviflora Sieb et Zucc can inhibit the replication of human immunodeficiency virus in vitro. 200 64

As an attempt to elucidate the pathogenesis of human immunodeficiency virus type 1 (HIV-1)-related cytopenia, the effects of infection of long-term primary bone marrow culture (LTBMC)-derived adherent cells on hematopoiesis were investigated. Productive infection could then be established only when using monocytotropic strains HIV-1Ba-L, HIV-1Ada, and HIV-1JR-FL but not with lymphocytotropic strain HIV-1LAI. Culture supernatants were tested for major cytokines involved in the regulation of hematopoiesis: neither IL-3 nor GM-CSF were detectable in the infected or noninfected cultures; in contrast, TGF-beta, TNF-alpha, MIP-1 alpha, Steel Factor, and IL-6 were detected at all times in established LTBMCs, but their levels were not consistently altered by virus replication. In vitro functional analysis by colony and long-term culture assays showed that HIV-1 infection failed to alter either the kinetics or the number of hematopoietic progenitors produced by the stromal layers; it did not interfere with the clonogenicity of exogeneous CD34+ cells in semisolid assays, and no difference was observed relative to the controls when HIV-1-infected stromal layers were tested for their ability to sustain long-term hematopoiesis. These results show that productive and sustained virus replication in the macrophage component of LTBMCs does not significantly alter the profile of major cytokines involved in regulating hematopoiesis, nor is it sufficient by itself for altering in vitro hematopoiesis under the baseline conditions used.
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PMID:In vitro infection of bone marrow-adherent cells by human immunodeficiency virus type 1 (HIV-1) does not alter their ability to support hematopoiesis. 748 69

In these studies we show that although purified B cells of patients with common variable immunodeficiency (CVI) have a normal capacity to proliferate, they manifest differentiation defects at multiple levels. Compared with controls, circulating CVI B cell populations contain reduced numbers of sIgG+ and sIgA+ cells with a commensurate increase in sIgM+ B cells, suggesting an in vivo defect in isotype switch. In addition, CVI B cells manifest Ig secretion defects on stimulation with either anti-CD40 and IL-10 or SAC and IL-2 and IL-10, which are of increasing severity for IgM, IgG, and IgA, respectively. These Ig secretion defects are not overcome by addition of a variety of cytokines, including TGF-beta, to anti-CD40-driven cultures. In further studies we show that despite the above abnormalities, CVI B cells are induced to express normal or near-normal levels of C mu, C gamma, and C alpha mRNA after 7 days of stimulation with anti-CD40 and IL-10. That this CH mRNA expression represents a recovery of CVI B cell differentiation is supported by studies of Ig secretion in which CVI B cells that are first stimulated for 7 days with anti-CD40 and IL-10 and then restimulated in coculture with activated normal allogeneic T cells and IL-10, secrete substantial levels of IgM and IgG and increased amounts of IgA. Overall, therefore, CVI B cell function can be significantly improved by maintenance in culture. These data suggest the abnormalities of B cell differentiation in CVI are reversible and that the defect is a form of B cell anergy.
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PMID:B cell differentiation defects in common variable immunodeficiency are ameliorated after stimulation with anti-CD40 antibody and IL-10. 751 19

Immunohistochemical localization of transforming growth factor beta 1 (TGF-beta 1) was studied in Kaposi's sarcoma (KS) tissues obtained from autopsy and biopsy materials of patients with and without acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus (HIV) infection. There was no difference in the localization and distribution of TGF-beta 1 in KS tissues regardless of the HIV-1 status of the patients. Rabbit polyclonal antibodies to synthetic peptides, corresponding to the first 30 amino acids of mature TGF-beta 1, anti-LC(1-30), and anti-CC(1-30), were used for localization of intracellular and extracellular TGF-beta 1. An antibody to a peptide corresponding to amino acids 266 to 278 of the TGF-beta 1 precursor sequence anti-Pre(266 to 278) was used to detect the TGF-beta 1 precursor and the latency-associated peptide. Intracellular mature TGF-beta 1 was demonstrated in mononuclear cells, presumably macrophages, within KS tumors but not in spindle-shaped KS cells. Extracellular mature TGF-beta 1 was localized in the basement membranes of blood vessels and fibrous capsules of KS tumors. Intracellular reactivity to anti-Pre was localized in vascular smooth muscle cells and pericytes within the tumor, in variable proportions of spindle-shaped KS cells, and also in macrophage-like cells. These cells appear to be the production sites of TGF-beta 1, which may exert paracrine as well as autocrine proliferative effects.
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PMID:Immunohistochemical localization of transforming growth factor-beta 1 in Kaposi's sarcoma. 775 Sep 30

Synovial fluid from patients with rheumatoid arthritis (RA-SF) contains in vivo produced cytokines and inflammatory mediators, including a factor that induces IgG2b production of lipopolysaccharide (LPS) preactivated murine B lymphocytes. In order to determine the mechanism by which RA-SF acts on LPS activated mouse B cells, CBA/N mice were used as an experimental model. The X-linked immunodeficiency of these mice is caused by a point mutation in the Bruton's tyrosine kinase (btk) gene. We have earlier shown that RA-SF can reconstitute the CBA/N B cell deficiency in vitro and in vivo, with regard to IgG2b production after LPS stimulation. Since transforming growth factor (TGF)-beta has been suggested to be a switch factor for IgG2b, we aimed at investigating the role of TGF-beta in our experimental system. We found that TGF-beta could not mimic the effect of RA-SF on CBA spleen cells. A small increase of IgG2b secretion was observed with spleen cells from normal CBA mice, whereas Ig secretion of all isotypes was suppressed in CBA/N spleen cells treated with TGF-beta at any concentration. Neutralizing antibodies against TGF-beta suppressed the response of CBA B cells, whereas the response by CBA/N B cells was enhanced by the same antibody preparation. Here we also show that the abnormal B cell responsiveness to TGF-beta, typical of CBA/N, co-segregates with the btk mutation in male (CBA x CBA/N)F2 spleen cells. This was determined by allele specific PCR recognizing the identified base substitutions of the btk gene, typical of the two strains. We propose that RA-SF contains a factor, separate from TGF-beta, that is involved in the differentiation of IgG2b expressing cells.
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PMID:Differential sensitivity to transforming growth factor (TGF)-beta of CBA and of CBA/N B cells demonstrates that the IgG2b inducing factor in synovial fluid from rheumatoid arthritis patients is not identical to TGF-beta. 779 24

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