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

Primary humoral immunodeficiency comprises a number of syndromes which in a descriptive manner indicate the nature and extent of the defect in the synthesis of specific antibodies and likewise of immunoglobulins. The understanding of humoral immunodeficiency has greatly advanced with the increase in knowledge about the cellular and molecular mechanisms of the development of B lymphocytes, which are the precursors of antibody-secreting plasma cells. This article reviews the advances made in the almost forty years that have passed since the first patient with agammaglobulinaemia was described. As far as X-linked agammaglobulinaemia is concerned, it is now clear that this is a disease of B lymphocytes, and that expression of the XLA gene prevents B cell development beyond the pre-B cell stage. Recent studies in patients with late-onset hypogammaglobulinaemia and selective IgA deficiency showed that there may be a common denominator for these two syndromes, since there is a close association with polymorphic antigens of the MHC class III region. Furthermore deletions or mutations of immunoglobulin genes can be the basis of selective deficiencies of one or several immunoglobulin isotypes. However, most of the humoral immunodeficiencies are based on defects in other non-immunoglobulin regulatory genes affecting or engaged in immunoglobulin-isotype synthesis. More recently patients have been described who have normal immunoglobulin isotype and complement levels and who show a selective defect in the antibody production to polysaccharide antigens. These patients most probably form a new disease entity in the spectrum of humoral immunodeficiency syndromes.
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PMID:Humoral immunodeficiency: from description to the cellular and molecular basis of the defect. 179 82

Carrier detection in X-linked immunodeficiencies (X-SCID, WAS, XLA) relies on the demonstration of non-random X inactivation patterns in blood cell lineages. Only a limited number of cells are available after cell separation methods. PCR-based techniques are therefore necessary to analyze active and inactive X chromosomes. Amplifying a polymorphic CAG repeat in the first exon of the androgen receptor gene after selective digestion of the active X chromosome with a methylation-sensitive restriction enzyme allows to distinguish between the paternal and maternal alleles and to identify their methylation status. DNA from B-, T-lymphocytes and total peripheral leukocytes of normal males, females and obligate carriers of X-linked immunodeficiencies were analyzed. The results of this PCR-based X inactivation assay are concordant with the standard methylation studies at the DXS255 locus using Southern blotting. This PCR assay provides a rapid and informative (heterozygosity > 90%) method in carrier detection of X-linked immunodeficiencies and other X-linked disorders, which show non-random X inactivation in cell lineages from the affected tissues.
Immunodeficiency 1995
PMID:A PCR based X-chromosome inactivation assay for carrier detection in X-linked immunodeficiencies using differential methylation of the androgen receptor gene. 774 38

In order to better understand the genomic diversity and molecular phylogeny of the human retroviruses, the plasmas from 250 Zairean patients collected in 1969 were tested for antibodies to human T-cell lymphoma and human immunodeficiency viruses (HTLV or HIV) using ELISA and confirmatory Western blots and for viral nucleic acids by reverse transcriptase-directed PCR (RT-PCR). Interestingly, none of the patients was confirmed positive for HIV, even though this region is now endemic for HIV-1. However, 74 (30%) and 3 (1%) of the samples were positive for antibodies to HTLV-I and II, respectively. Forty-four of 74 (59%) Western blot-positive Zairean samples were RT-PCR positive for HTLV-I, while 1 of 3 (33%) of HTLV-II-seropositive samples was RT-PCR positive. On the contrary, none of the Western blot-negative or indeterminate samples were RT-PCR positive for either HTLV-I or HTLV-II. We have cloned and sequenced 140 bp of the pol gene flanked by SK110/SK111 from 8 HTLV-I- and 1 HTLV-II-positive archival samples from Zaire. The HTLV-I isolates from Zaire cluster together as a phylogenetic group, diverging from the prototype Japanese HTLV-I (ATK) by a range of 1.4 to 3.6%. Their close homology to some African STLV-I isolates suggests relatively recent interspecies transmission. The Zairean HTLV-II isolate is closely grouped with the HTLV-II substrain of isolates found in Paleo-Amerindians of the New World, making it unlikely that it represents an endemic African strain.
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PMID:Serological and nucleic acid analyses for HIV and HTLV infection on archival human plasma samples from Zaire. 791 21

Serum levels of the soluble form of the low-affinity receptor for IgE (FcERII, CD23) (sCD23) are elevated in autoimmune conditions associated with hypergammaglobulinaemia and B cell hyperactivity. Very high levels of sCD23 are found in patients with B-chronic lymphatic leukaemia (B-CLL) who are, however, frequently hypogammaglobulinaemic. We therefore compared the serum levels of sCD23 in healthy controls (n = 33) with three conditions associated with hypogammaglobulinaemia (HGG) and varying B cell numbers: X-linked agammaglobulinaemia (XLA, n = 12), common variable immunodeficiency (CVI, n = 20) and B-chronic lymphatic leukaemia (n = 33). Serum levels of sCD23 showed a significant correlation with the CD19+ B cell count in both normals and patients with CVI (r = 0.65, P < 0.0001). Amongst the different clinical groups, serum levels of sCD23 were increased in the order XLA < CVI < normals < CLL (medians 2.5, 7.7, 11.1 and 540, respectively; P < 0.001 for all comparisons except CVI versus normals P < 0.03 in a one-tailed test). In the CVI group, serum sCD23 was lowest amongst four patients with low B cell numbers. There was no overlap in sCD23 between patients with XLA and this subgroup of CVI patients. Serum sCD23 is, therefore, derived predominantly from B cells, and is significantly related to the peripheral blood B cell count.
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PMID:Serum soluble CD23 in patients with hypogammaglobulinaemia. 805 Jan 71

X chromosome-linked agammaglobulinemia is a life-threatening disease that involves a failure in normal development of B lymphocytes and is associated with missense mutations in BTK, a gene encoding a cytoplasmic tyrosine kinase (Bruton agammaglobulinemia tyrosine kinase, EC 2.7.1.112), a member of the Tec family of protein-tyrosine kinases. The genomic organization has been determined by using conventional restriction fragment mapping, extended DNA sequencing, and PCR fragment-sizing approaches. The DNA sequences of the 18 coding exons composing BTK and their flanking-region sequences are reported; an additional exon(s) encodes a 5' untranslated segment. Single-base-pair substitutions and 4-nt deletions resulted in amino acid replacement, premature termination, frameshift, and exon deletion in a group of X chromosome-linked agammaglobulinemia patients exhibiting different clinical presentations and courses. The nature of the mutations is interpreted in terms of the genomic organization of the BTK gene and the disease course in individual patients. Several examples are found in which the same mutation occurs in unrelated patients, and one of these mutations occurs at the same codon that is substituted in the murine form of BTK, resulting in X chromosome-linked immunodeficiency disease. Considerable variation in presentation and disease course in X chromosome-linked agammaglobulinemia appears associated with the nature and position of different missense mutations.
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PMID:Genomic organization and structure of Bruton agammaglobulinemia tyrosine kinase: localization of mutations associated with varied clinical presentations and course in X chromosome-linked agammaglobulinemia. 809 Jul 69

We describe a novel cytoplasmic tyrosine kinase, termed BPK (B cell progenitor kinase), which is expressed in all stages of the B lineage and in myeloid cells. BPK has classic SH1, SH2, and SH3 domains, but lacks myristylation signals and a regulatory phosphorylation site corresponding to tyrosine 527 of c-src. BPK has a long, basic amino-terminal region upstream of the SH3 domain. BPK was evaluated as a candidate for human X-linked agammaglobulinemia (XLA), an inherited immunodeficiency characterized by a severe deficit of B and plasma cells and profound hypogammaglobulinemia. BPK mapped to within 100 kb of a probe defining the polymorphism most closely linked to XLA at DXS178. Reduction in or the absence of BPK mRNA, protein expression, and kinase activity was observed in XLA pre-B and B cell lines. BPK is likely the XLA gene and functions in pathways critical to B cell expansion.
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PMID:Deficient expression of a B cell cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia. 842 21

Mutations in the Bruton's tyrosine kinase (BTK) gene result in XLA. Despite the large numbers of BTK mutations reported, no correlation can be made between the clinical phenotype and the gene defects. Analysis of Btk protein expression and activity in individuals with XLA was performed to characterize the relationship between a particular mutation, the resultant Btk protein and the clinical phenotype. In most patients studied, including those with atypical phenotypes, there was complete absence of protein expression and activity. Furthermore, in two undiagnosed individuals with a clinical phenotype suggestive of XLA, lack of protein expression was used to confirm an abnormality in Btk. These results underline the importance of protein analysis prior to speculating on protein structure and function based on the gene mutation. Lack of Btk expression in atypical phenotypes suggests that there is redundancy in B lymphocyte signalling such that alternative signalling molecules, or mechanisms, can compensate for the lack of Btk. We also suggest that analysis of Btk expression can be used as an indicator of XLA. These rapid assays may be used to screen a wider spectrum of individuals with humoral immunodeficiency in order to characterize fully the extent of Btk deficiency.
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PMID:Bruton's tyrosine kinase expression and activity in X-linked agammaglobulinaemia (XLA): the use of protein analysis as a diagnostic indicator of XLA. 948

We report a case of sporadic X-linked agammaglobulinemia previously diagnosed as variable immunodeficiency (VID). An 39-year-old male had recurrent episodes of respiratory tract infection since his early childhood. At the age of four, he developed partial paresis of the left limbs after polio immunization. After diagnosis of VID based on marked decrease of serum IgG, IgA and IgM levels and no antibody production against antigenetic stimuli at age 22 years old, he received intravenous immunoglobulin supplementation irregularly. We reexamined him and found marked decrease in B cells in the peripheral blood. In addition, we investigated the expression of Bruton-type tyrosine kinase on monocytes by flow cytometry and confirmed its deficiency. His mother was diagnosed as a carrier of XLA. The patient is probably the oldest case with XLA in Japan.
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PMID:[The oldest case with X-linked agammaglobulinemia in Japan lacking Bruton-type tyrosine kinase protein detected by flow cytometry]. 949 52

Bruton's tyrosine kinase, which is encoded by the BTK gene, is a cytoplasmic protein tyrosine kinase (PTK) crucial for B-cell development and differentiation. It belongs to the Tec family of PTKs containing several domains that are characteristic of signalling molecules. In humans, mutations that disrupt the function of this gene lead to the classical XLA syndrome (X-linked agammaglobulinaemia), a primary immunodeficiency mainly characterized by lack of mature B cells as well as low levels of immunoglobulins. In contrast, animal models of this disease such as the xid mice display profoundly milder XLA phenotype. BTK phosphorylation and activation in response to engagement of the B-cell receptor (BCR) by antigen is a dynamic process whereby a variety of proteins interact with each other and recruit signalling molecules resulting in a physiological response such as B-cell proliferation and antibody production. The main players, however, that participate in the intracellular downstream cascade have not yet been identified and are therefore under intense scrutiny in several laboratories. This review discusses certain aspects of BTK activation following receptor stimulation by agonists and how this event is translated into the biochemical signals within the cell that eventually lead to nuclear responses.
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PMID:Signalling of Bruton's tyrosine kinase, Btk. 1007 13

Bruton's tyrosine kinase (Btk) plays crucial roles in B cell differentiation as well as mast cell activation through the high-affinity IgE receptor (FcepsilonRI). Defects in the btk gene lead to agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (xid) in mice. Mast cells from xid and btk null mice exhibit mild defects in degranulation and severe impairments in the production of proinflammatory cytokines upon FcepsilonRI cross-linking. Recent studies demonstrated the role of Btk in a sustained increase in intracellular calcium concentrations in response to antigen receptor stimulation. Btk is also involved in the activation of stress-activated protein kinases, JNK/SAPK1/2, and thereby regulates c-Jun and other transcription factors that are important in cytokine gene activation. Regulation of the JNK/SAPK activation pathway by Btk may be related to the proapoptotic function of Btk in the programmed cell death in these hematopoietic cells.
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PMID:Functions of Bruton's tyrosine kinase in mast and B cells. 1008 May 29


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