Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bruton's tyrosine kinase (Btk) plays a critical role in B cell Ag receptor (BCR) signaling, as indicated by the X-linked immunodeficiency and X-linked agammaglobulinemia phenotypes of mice and men that express mutant forms of the kinase. Although Btk activity can be regulated by Src-family and Syk tyrosine kinases, and perhaps by phosphatidylinositol 3,4,5-trisphosphate, BCR-coupled signaling pathways leading to Btk activation are poorly understood. In view of previous findings that CD19 is involved in BCR-mediated phosphatidylinositol 3-kinase (PI3-K) activation, we assessed its role in Btk activation. Using a CD19 reconstituted myeloma model and CD19 gene-ablated animals we found that BCR-mediated Btk activation and phosphorylation are dependent on the expression of CD19, while BCR-mediated activation of Lyn and Syk is not. Wortmannin preincubation inhibited the BCR-mediated activation and phosphorylation of Btk. Btk activation was not rescued in the myeloma by expression of a CD19 mutant in which tyrosine residues previously shown to mediate CD19 interaction with PI3-K, Y484 and Y515, were changed to phenylalanine. Taken together, the data presented indicate that BCR aggregation-driven CD19 phosphorylation functions to promote Btk activation via recruitment and activation of PI3-K. Resultant phosphatidylinositol 3,4,5-trisphosphate probably functions to localize Btk for subsequent phosphorylation and activation by Src and Syk family kinases.
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PMID:Phosphorylation of CD19 Y484 and Y515, and linked activation of phosphatidylinositol 3-kinase, are required for B cell antigen receptor-mediated activation of Bruton's tyrosine kinase. 1020 80

Bruton's tyrosine kinase (Btk) is a nonreceptor protein kinase that is defective in X-linked agammaglobulinemia in humans and in X-linked immunodeficiency in mice. To study the effect of Btk activation in early B cell development in vivo, we have created transgenic mouse strains expressing Btk under the control of the human CD19 promoter region. The transgenic expression of wild-type human Btk corrected all X-linked immunodeficiency features in mice carrying a targeted disruption of the Btk gene. In contrast, expression of an activated form of Btk, the E41K mutant, resulted in an almost complete arrest of B cell development in the immature IgM+IgD- B cell stage in the bone marrow, irrespective of the presence of the endogenous intact Btk gene. Immature B cells were arrested at the progression from IgMlow into IgMhigh cells, which reflects the first immune tolerance checkpoint at which autoreactive B cells become susceptible to apoptosis. As the constitutive activation of Btk is likely to mimic B cell receptor occupancy by autoantigens in the bone marrow, our findings are consistent with a role for Btk as a mediator of B cell receptor-induced apoptotic signals in the immature B cell stage. Whereas the peripheral mature B cell pool was reduced to <1% of the normal size, significant numbers of IgM-secreting plasma cells were present in the spleen. Serum IgM levels were substantial and increased with age, but specific Ab responses in vivo were lacking. We conclude that the residual peripheral B cells were efficiently driven into IgM+ plasma cell differentiation, apparently without functional selection.
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PMID:Early arrest in B cell development in transgenic mice that express the E41K Bruton's tyrosine kinase mutant under the control of the CD19 promoter region. 1035 68

Human thymoma is a neoplasm of thymic epithelial cells associated with several clinical syndromes ranging from autoimmune disease to immunodeficiency. The aim of our research was to investigate T cell-mediated immune response in patients with thymoma. Initially eight patients were enrolled in this study. Four patients underwent surgical removal of the thymus, while four were submitted to diagnostic procedures only. Inversion of the CD4:CD8 ratio was found in three patients. Only one subject displayed a normal CD19 count in peripheral blood. The mean value (+/-SD) of the CD19 percentage in the patient group was 2 +/- 2.2. Notably, the patients with thymoma had fewer mature B lymphocytes than the thymectomized patients. The T-cell receptor (TCR) repertoire was investigated in three individuals affected by thymoma: one underwent thymectomy, while the two others, one of which presented with lymphocytosis, were submitted to diagnostic biopsies only. The preliminary results showed a marked alteration in the CD8 repertoire of the thymectomized patient but not in that of the lymphocytotic patient. However, alterations in the TCR repertoire were also found in one patient with thymoma. Altogether, these preliminary findings reveal that loss of CD19+ lymphocytes in peripheral blood is a frequent phenomena in thymoma patients. In this article we discuss this aspect in the context of alterations of the TCR repertoire.
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PMID:Immunological findings in thymoma and thymoma-related syndromes. 1057 62

FIRST REPORT: male child with repeated pulmonary infections from the age of 4 months. He was diagnosed as IgA deficiency (undetectable IgA levels) at the age of 3 years, when he presented repeated bouts of pneumonia and tonsillitis. Several immunologic evaluations were made between the ages of 4 months and 8 years. At 8 years and 9 months, the diagnosis of IgA deficiency was confirmed, and associated IgG2 and IgG4 deficiency (29.0 mg/dl y 0.01 mg/dl) with normal total IgG serum level was found. With the administration of intravenous gammaglobulin, the lung infections remitted and the subsequent clinical course has been uneventful up to now. SECOND REPORT: a boy with repeated infections since the age of 2 months. IgA deficiency was diagnosed at 1 year 7 months (undetectable serum IgA levels). At age 51/2 years, his clinical course worsened and more serious infections appeared. A new immunologic study revealed IgA deficiency associated with CD4 cell deficiency (432 cells/mm3) and normal CD3, CD19, and CD8 levels. Despite intensive antibiotic treatment and care, the child died. The findings suggest an association of IgA deficiency and common variable immunodeficiency.
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PMID:Evolution of IgA deficiency to IgG subclass deficiency and common variable immunodeficiency. 1075 54

The molecular mechanism of pneumococcal vaccine failure in human immunodeficiency virus (HIV)-infected persons is not fully understood. A polymerase chain reaction ELISA was used to determine the proportion of peripheral IgG, IgA, and IgM CD19-positive B cells expressing 6 immunoglobulin heavy-chain variable region (VH) subgroups before and 7 days after pneumococcal vaccination of 12 HIV-infected and 12 HIV-uninfected subjects. Significant postvaccination increases in the expression of the VH3 subgroup by IgG and IgA and a greater serologic response to vaccination were observed in the HIV-uninfected group. In contrast, the HIV-infected group had reduced prevaccination IgG VH3 and a postvaccination increase in IgG VH5. These results demonstrate that pneumococcal vaccination changes the pattern of B cell VH gene expression and support the concept that aberrant VH3 expression may translate into a poor antipneumococcal response in the setting of HIV infection.
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PMID:A pneumococcal capsular polysaccharide vaccine induces a repertoire shift with increased VH3 expression in peripheral B cells from human immunodeficiency virus (HIV)-uninfected but not HIV-infected persons. 1076 63

CCR5 and CXCR4 are the major coreceptors that mediate human immunodeficiency virus 1 (HIV-1) infection, while most simian immunodeficiency virus (SIV) isolates use CCR5. A number of alternative coreceptors can also mediate infection of some virus strains in vitro, although little is known about their in vivo relevance. Therefore, we characterized the expression pattern and coreceptor activity of one of these alternative coreceptors, STRL33/Bonzo, using a newly developed monoclonal antibody. In addition to being highly expressed (approximately 1000-7000 STRL33 ABS [antibody binding sites]) on specific subsets of natural killer cells (CD3(-)/CD16(-/low)/CD56(+) and CD3(-)/CD16(low)/CD56(-)) and CD19(+) B lymphocytes (approximately 300-5000 STRL33 ABS), STRL33 was expressed at levels sufficient to support virus infection on freshly isolated, truly naive CD4(+)/CD45RA(+)/CD62L(+) cells (6000-11 000 ABS). STRL33 expression on peripheral blood mononuclear cells (PBMCs) was increased by mitogenic stimulation (OKT3/IL-2 [interleukin-2] had a greater effect than phytohemaglutinin (PHA)/IL-2), but it was dramatically decreased upon Ficoll purification. Infection of CCR5(-) human peripheral blood lymphocytes (PBLs) showed that 2 different SIV envelope (Env) proteins mediated entry into STRL33(+) cells. More importantly, the preferential infection of STRL33(+) cells in CCR5(-) PBLs by an R5/X4/STRL33 HIV-1 maternal isolate in the presence of a potent CXCR4 antagonist (AMD3100) suggests that STRL33 can be used as a coreceptor by HIV-1 on primary cells. Rhesus macaque (rh) STRL33 was used less efficiently than human STRL33 by the majority of SIV Env proteins tested despite similar levels of expression, thereby making it less likely that STRL33 is a relevant coreceptor in the rhesus macaque system. In summary, the expression pattern and coreceptor activity of STRL33 suggest its involvement in trafficking of tumor-infiltrating lymphocytes and indicate that STRL33 may be a relevant coreceptor in vivo.
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PMID:Expression and coreceptor activity of STRL33/Bonzo on primary peripheral blood lymphocytes. 1089 28

In the process of developing a decision support system based on flow cytometric data for the diagnosis of immunodeficiency, assessment of lymphocyte subpopulations in human peripheral blood provides the key for further analysis. Samples from 273 'healthy' Hungarian subjects were measured between 1998 and 1999. Immunophenotypic data are compared here (unadjusted for gender) by different age groups: I 0-6 years (n=45); II 7-18 years (n=71); III 19-35 years (n=72); IV 36-55 years (n=48); and V 56-99 years (n=37). Two-color flow cytometric analysis was performed using the Becton Dickinson Simultest IMK Plus kit (CD45/CD14, isotype control, CD3/CD19, CD4/CD8, CD3/HLA-DR, CD3/CD16+56). All lymphocyte subpopulations were measured in all blood samples identically. The quality criteria involved at least 95% of total lymphocytes in the analysis gate, homogenous CD45+ lymphocyte population (minimum of 2000 events in the gate, CD45+ >95%). The frequency of B lymphocytes was the highest, significantly, in the youngest Hungarian subjects, but there were no significant changes with age comparing the data of other II-V age groups. On the other hand, some T subpopulations changed with aging; both CD4 and CD8 subsets varied over time including the elevation of the fraction of activated T cells as well as LGL-NK cells. Some of these changes were significant by statistical tests. Interpretation of flow cytometric data is time-consuming and requires human knowledge of an expert laboratory staff. To facilitate the diagnosis of immunodeficiency, a pilot study aiming at the development of a diagnostic algorithm has been initiated. Algorithm nodes compare the frequency of each lymphocyte subpopulations to the generated reference values. This knowledge-based system describes a short summary report as a result of the comparison, and points to some values requiring further human examination to reach a final conclusion. These reference values and the expert system appear to be a recommended basis for comparing and combining results from different laboratories.
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PMID:Developing an expert system for immunophenotypical diagnosis in immunodeficiency. Age-related reference values of peripheral blood lymphocyte subpopulations in Hungary. 1134 69

The B-cell lineage in a patient with B-cell-negative severe combined immunodeficiency (SCID) was analysed by using antisurrogate light chain (SL) MoAbs. Peripheral CD3(+) T cells and CD19(+) B cells were absent in the patient. The common gamma (gamma c) chain was expressed normally on the patient's peripheral NK cells and his peripheral mononuclear cells did not possess any mutations in recombinase activating gene (RAG)-1, 2. Normal levels of expression of Ku70 and Ku80 protein were found by Western blot analysis. The patient did, however, display an increase in fibroblast sensitivity to irradiation. Furthermore, flow cytometric analyses of bone marrow cells showed that surface IgM and cytoplasmic mu positive cells were absent and that CD19(+) B cells were composed of only CD34(+) terminal deoxynucleotidyl transferase (TdT)(+) SL(+) pro-B cells. The complete arrest of pro- to pre-B cell development in the SCID patient's bone marrow suggests that some genes involved in V(D)J recombination, excepting the RAG gene, may play a causative role in the immunodeficiency.
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PMID:Complete arrest from pro- to pre-B cells in a case of B cell-negative severe combined immunodeficiency (SCID) without recombinase activating gene (RAG) mutations. 1147 8

Careful longitudinal studies of the lymphoid cell recovery after stem cell transplantation with other than HLA-identical sibling donors illustrated the prolonged T- and B-cellular immunodeficiency post-SCT, whereas NK-cell recovery was fast. Only low numbers of CD45RO memory T-cells, with a restricted TCR-repertoire, are present in the first 6 months post-SCT. The consequence is an increased risk of viral infections and possibly of leukemia relapse. The latter complication can be prevented by enhancing the anti-leukemic immune reactivity shortly after SCT. Different technical approaches were presented, the majority of them still being in the pre-clinical phase. NK-cell reactivity based on KIR-epitope mismatches between donor and recipient are promising for AML- and CML-, not for ALL-patients. The ALL-blasts may be killed by an antibody-dependent cellular cytotoxicity, using anti-CD19 antibodies, as was shown to be effective in vitro. Also the generation of leukemia-specific CTL's, making use of differences in minor histocompatibility antigens between donor and recipient, is now operational and may be a highly effective approach in a number of leukemic graft recipients.
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PMID:Immune recovery and immunotherapy after stem cell transplantation in children. 1157 27

Flow cytometry is an important tool for the diagnosis and follow-up of immunodeficiency patients, as well as for patients with leukemia and lymphoma. Lymphocytes and their subsets show variations with race. The aim of this study was to establish reference ranges for lymphocytes and their subsets in an Saudi adult population by using flow cytometry. Blood samples obtained from 209 healthy Saudi men were used for this study. All blood donors were between 18 and 44 years old. Lymphocytes and their subsets were analyzed by flow cytometry, and the absolute and percentage values were calculated. We investigated the expression of T-cell markers (CD3, CD4, and CD8), B cells (CD19), and natural killer cells (CD16 and CD56). The absolute and percent values of each cell subset were compared with published data from different populations by using the Student t test. Reference ranges, each expressed as the mean +/- the standard deviation, were as follows: leukocytes (6,335 +/- 1759), total lymphocytes (2,224 +/- 717), CD3 cells (1,618 +/- 547), CD4 cells (869 +/- 310), CD8 cells (615 +/- 278), CD19 cells (230 +/- 130), and CD3-CD16(+)/CD56+ cells (262 +/- 178). The CD4/CD8 ratio was 1.6 +/- 0.7. Our results for B cells, CD4 cells, and CD8 cells and for the CD4/CD8 ratio fell in between the reported results for Ethiopian and Dutch subjects. Our results were also different from previously reported findings in an Saudi adult population that showed no increase in CD8 T cells. We thus establish here the reference ranges for lymphocytes and their subsets in a large cohort of Saudi men. The CD8 cell count was not abnormally high, as previously reported, and fell in between previous results obtained for African and European populations.
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PMID:Immunophenotyping of peripheral blood lymphocytes in Saudi men. 1187 63


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