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M D Cooper

Publications and source records attributed to M D Cooper.

At least 19 recordsLinked to original sources
PubMed1992

Heterogeneity of immunoglobulin-associated molecules on human B cells identified by monoclonal antibodies.

Two covalently linked transmembrane molecules, encoded in mice by the mb-1 and B29 genes, have been defined as integral components of the antibody receptor units expressed on B cells. We have produced monoclonal antibodies against an exposed extracellular epitope on the putative human equivalent of the mouse B29 product. These antibodies, CB3-1 and -2, were used to show that cytoplasmic expression of this molecule begins in human pro-B cells (terminal deoxynucleotidyltransferase-positive, mu chain-negative), whereas surface expression coincides strictly with surface immunoglobulin expression of all isotypes. Immunochemical analysis of the human immunoglobulin-associated molecules revealed greater molecular heterogeneity than has been noted for the murine analogues. This molecular heterogeneity of immunoglobulin-associated molecules varied as a function of differentiation stage and the immunoglobulin isotypes expressed by B-lineage cells. Our data support the hypothesis that biochemical heterogeneity of the surface immunoglobulin-associated molecules may contribute to the variability in biological effects of antigen receptor crosslinkage on B cells of different maturational stages. Because the CB3 antibodies are capable of down-modulating the antigen receptors on all B cells, they may prove therapeutically useful as universal B-cell suppressants.

Antibodies, Monoclonal↗
PubMed1992

Molecular heterogeneity of Fc alpha receptors detected by receptor-specific monoclonal antibodies.

Fc alpha receptors (Fc alpha R) were isolated from a human monocytic cell line and used to raise four mAb with receptor specificity. The antibodies were used to identify the types of white blood cells that express Fc alpha R and the molecular heterogeneity of the receptor molecules. Nonpolymorphic epitopes, outside of the Fc alpha-binding site, were recognized only on blood cells of granulocyte and monocyte/macrophage lineages. The molecules identified, both by the antibodies and by the IgA ligand, were glycoproteins ranging in relative molecular mass from 55 to 75 kDa. However, one antibody detected a subpopulation of Fc alpha R molecules characterized by relatively restricted size heterogeneity. A complex glycosylation pattern was revealed by the resolution of discrete 32- and 36-kDa molecular species after removal of N-linked oligosaccharides and by evidence for O-linked carbohydrate moieties on at least a portion of the Fc alpha R molecules. In biosynthetic studies, all four anti-Fc alpha R antibodies and the IgA ligand bound a single 32-kDa core protein present in tunicamycin-treated cells, and the exceptional antibody again recognized molecules with relatively restricted glycosylation in the nontreated cells. These antibodies and native IgA ligands thus provide complementary reagents for definition of the complex structure and function of Fc alpha R in systemic IgA antibody responses.

Antibodies, Monoclonal↗
PubMed1992

Genetic and immunologic analysis of a family containing five patients with common-variable immune deficiency or selective IgA deficiency.

A family with 13 members included 2 subjects with selective IgA deficiency (IgA-D) and 3 subjects with common-variable immune deficiency (CVID), diseases which usually occur sporadically. Reciprocal combinations of B and T cells in vitro between one normal and two immune-deficient family members and normal subjects revealed that defective Ig synthesis was determined by the B cells, while the patient T cells functioned normally. Normal T helper and suppressor function was demonstrated even in one patient with CVID who developed a T-cell lymphoproliferative disorder associated with elevated IgM; this patient's B cells made only IgM in vitro. Immune deficiencies were inherited in this family in a pattern consistent with an autosomal dominant trait with incomplete penetrance. All the immune-deficient patients in this family possessed at least one copy of an MHC haplotype previously shown to be abnormally frequent in IgA-D and CVID: HLA-DQB1*0201, HLA-DR3, C4B-Sf, C4A-deleted, G11-15, Bf-0.4, C2-a, HSP70-7.5, TNF alpha-5, HLA-B8, and HLA-A1. The patient who developed the lymphoproliferative disorder was homozygous for this haplotype. Four immunologically normal members, one of whom was 80 years old, also possessed this MHC haplotype, indicating that its presence is not sufficient for disease expression. A small segment of another MHC haplotype associated with Ig deficiency in the population also occurred in this family, but it was not associated with immune deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Immunization-induced decrease of the CD4+:CD8+ ratio in cats experimentally infected with feline immunodeficiency virus.

In a previous experiment a group of 15 specified pathogen free (SPF) cats were experimentally infected with a Swiss isolate of feline immunodeficiency virus (FIV). A group of 15 SPF cats served as FIV negative controls. Nine cats of each group were vaccinated with a recombinant feline leukemia virus (FeLV) vaccine, six cats in each group with a placebo vaccine. All vaccinated cats developed high antibody titers to FeLV and were protected against subsequent FeLV challenge infection. In both control groups five of six cats became persistently infected with FeLV. Unexpectedly, the primary immune response to the vaccine antigen was significantly higher in the FIV positive group than in the FIV negative. The secondary response was stronger in the FIV negative cats. The goal of the present investigation was to further study the immune response in these 30 cats. They were immunized twice with the synthetic peptide L-tyrosine-L-glutamic acid-poly(DL-alanine)-poly(L-lysine) (TGAL) 21 days apart. Blood samples were collected on four occasions during the immunization process. They were tested for antibodies to TGAL, complete blood cell counts and CD4+, CD8+ and pan-T-lymphocyte counts. The following observations were made: (1) in contrast to the FeLV vaccine experiment, the primary immune response to TGAL was not significantly stronger in the FIV positive cats when tested by enzyme-linked immunosorbent assay (2). The absolute size of the CD4+ lymphocyte population was distinctly smaller in the FIV positive than in the FIV negative cats. The lowest CD4+ values were found in the dually FIV/FeLV infected cats. (3) A population of CD8+ lymphocytes was identified that was characterized by a distinctly weaker fluorescence. The size of this population increased in FIV positive and decreased in FIV negative cats during the TGAL immunization experiment. (4) The CD4+:CD8+ ratio increased in FIV negative cats during TGAL immunization from 1.9 to 2.3. In contrast, in FIV positive animals the CD4+:CD8+ ratio decreased significantly from 1.9 to 1.3 during the same period. From these and earlier data it was concluded that in short-term FIV infection the immune response to T-cell dependent antigens may be increased over that of the controls. Immune suppression develops gradually with duration of the infection. The significant drop of the CD4+:CD8+ ratio over a 5 week immunization period suggests that antigenic stimulation may accelerate the development of immune suppression in FIV positive cats. If this is a general feature, FIV infection may provide a particularly interesting model for studying the pathogenesis of AIDS.

Amino Acid Sequence↗
PubMed1992

Major histocompatibility complex class III genes and susceptibility to immunoglobulin A deficiency and common variable immunodeficiency.

We have proposed that significant subsets of individuals with IgA deficiency (IgA-D) and common variable immunodeficiency (CVID) may represent polar ends of a clinical spectrum reflecting a single underlying genetic defect. This proposal was supported by our finding that individuals with these immunodeficiencies have in common a high incidence of C4A gene deletions and C2 rare gene alleles. Here we present our analysis of the MHC haplotypes of 12 IgA-D and 19 CVID individuals from 21 families and of 79 of their immediate relatives. MHC haplotypes were defined by analyzing polymorphic markers for 11 genes or their products between the HLA-DQB1 and the HLA-A genes. Five of the families investigated contained more than one immunodeficient individual and all of these included both IgA-D and CVID members. Analysis of the data indicated that a small number of MHC haplotypes were shared by the majority of immunodeficient individuals. At least one of two of these haplotypes was present in 24 of the 31 (77%) immunodeficient individuals. No differences in the distribution of these haplotypes were observed between IgA-D and CVID individuals. Detailed analysis of these haplotypes suggests that a susceptibility gene or genes for both immunodeficiencies are located within the class III region of the MHC, possibly between the C4B and C2 genes.

Agammaglobulinemia↗
PubMed1992

Characterization of a feline T-cell-specific monoclonal antibody reactive with a CD5-like molecule.

The 43 monoclonal antibody raised against feline T cells was found to react with a single-chain glycoprotein of Mr 72,000 that is present on most thymocytes, 60% of lymph node cells, 20% of splenocytes, and 45% of blood mononuclear cells. All CD4+ and CD8+ T cells were found to express the 43-reactive determinant, as did a small subpopulation of CD4-/CD8-/IgM- lymphocytes in the periphery. The 43-reactive determinant was not detected on B cells, macrophages, or other types of blood cells. The 43 antigen was phosphorylated in resting and activated T cells. Its expression was upregulated by stimulation with phorbol myristate acetate and with phytohemagglutinin. When added to concanavalin A-stimulated T-cell cultures in low concentrations, the 43 antibody was found to augment mitogenesis. The data indicate that this antibody may identify a CD5 homologue on feline T cells.

Animals↗
PubMed1991

T cells expressing the V beta 1 T-cell receptor are required for IgA production in the chicken.

While alpha beta T cells in mammals may express one of many variable (V) gene families in the beta locus, chickens have only two V beta gene families. The avian V beta 2+ T cells are recognized by the T-cell receptor 3 (TCR3) monoclonal antibody and V beta 1+ T cells are recognized by the TCR2 antibody, which we used to selectively suppress development of V beta 1+ T cells in order to examine their functional role. Suppression was accomplished by multiple injections of anti-TCR2 antibodies beginning in embryonic life and perpetuated by thymectomy 8 days after hatching. Young birds thus depleted of V beta 1+ T cells had greater than normal numbers of V beta 2+ T cells and appeared as healthy as thymectomized and untreated controls. While production of IgM and IgG antibodies was unimpaired, IgA antibody production was severely compromised in the V beta 1-depleted birds. The levels of secretory IgA in bile and lung lavage fluid were reduced 1000- to 10,000-fold and secretory IgA antibodies were not produced in response to mucosal immunization. B-cell production of IgA antibodies thus appears to require T cells expressing the V beta 1 genes, whereas T cells that express the V beta 2 genes lack this capacity.

Animals↗
PubMed1991

Two distinct alpha beta T-cell lineages can be distinguished by the differential usage of T-cell receptor V beta gene segments.

Avian T cells can be divided into three subpopulations based on their expression of distinct T-cell receptors (TCR1, TCR2, and TCR3), ontogeny, and tissue distribution. The TCR1 cells appear to be the equivalent of mammalian gamma delta cells, but the derivation of cells expressing TCR2 and TCR3 has been unclear. Here we report that chickens contain two families of TCR beta variable (V) gene segments, V beta 1 and V beta 2. Furthermore, TCR2 and TCR3 represent subsets of alpha beta cells that are defined by mutually exclusive usage of these two families of V beta gene segments. Sequence comparisons of V beta 1 and V beta 2 with mammalian TCR beta V segments reveal that V beta 1 gene segments encode the conserved amino acids used to define the mammalian V beta consensus subgroup I, while V beta 2 encodes the amino acids used to define the mammalian V beta subgroup II. Although the beta chains of TCR2 and TCR3 cells are encoded by the same diversity (D), joining (J), and constant (C) region segments, V beta 1 gene segments undergo rearrangement before V beta 2 gene segments during T-cell development. This may result from the fact that TCR2 cells undergo V-DJ joining by deletional rearrangement, whereas TCR3 cells undergo V-DJ joining by inversional rearrangement. These data suggest that the TCR alpha beta cells can be divided into two distinct and evolutionarily conserved lineages based on V beta gene segment usage. The clear-cut separation of these lineages in the chicken may help to define their immunologic role.

Aging↗
PubMed1991

Normal pre-B cells express a receptor complex of mu heavy chains and surrogate light-chain proteins.

Precursors of B cells, which constitute a subpopulation of the lymphocytes in bone marrow, can be identified by their surface expression of nonimmunoglobulin markers and the absence of immunoglobulin kappa and lambda light chains. Most pre-B cells synthesize mu heavy chains but, without light-chain partners, these undergo rapid cytoplasmic degradation. In the present study, we demonstrate that late stage pre-B cells, like their neoplastic counterparts, express low levels of a surface receptor composed of mu chains paired with a surrogate light-chain complex formed by Vpre-B and lambda 5-like proteins. The data define a previously suspected but unrecognized stage in normal pre-B-cell differentiation. Expression of a clonally diverse receptor renders this population of immature B-lineage cells potentially vulnerable to clonal selection by antigens and idiotypic interactions.

Antibody Formation↗
PubMed1991

Aminopeptidase A activity of the murine B-lymphocyte differentiation antigen BP-1/6C3.

The predicted amino acid sequence of the cDNA encoding the murine B-lymphocyte differentiation antigen BP-1/6C3 suggested that it is a member of the zinc-dependent metalloprotease family, possibly an aminopeptidase related to aminopeptidase N [microsomal aminopeptidase; alpha-aminoacyl-peptide hydrolase (microsomal), EC 3.4.11.2]. In the present studies, we examined the enzymatic activity of this antigen. From brush border preparations of the small intestine, a rich source of many endopeptidases and exopeptidases, the BP-1 antibody selectively removed aminopeptidase A [APA; L-alpha-aspartyl(L-alpha-glutamyl)-peptide hydrolase, EC 3.4.11.7] activity. The APA activity of a panel of cell lines correlated in linear fashion with cell-surface levels of the BP-1/6C3 antigen. APA activity was demonstrated for the BP-1/6C3 antigen immunopurified from the pre-B-cell membrane. This activity was enhanced by alkaline earth metals such as Ca2+ and was abrogated by amastatin and angiotensin, which are known competitive inhibitors of APA. The data indicate that the murine BP-1/6C3 antigen is active APA, an enzyme that catalyzes specifically the removal of unsubstituted, N-terminal glutamic acid and aspartic acid residues from peptides.

Aminopeptidases↗
PubMed1991

Isotype commitment of human B cells that are transformed by Epstein-Barr virus.

Epstein-Barr virus (EBV) can transform a subpopulation of preactivated B cells thus promoting their growth and differentiation into plasma cells. In EBV-transformed clones of IgM-producing cells, the heavy chain constant region (CH) genes on the productive allele are fixed in germ-line configuration, whereas in isotype-switched clones the CH genes proximal to the expressed CH gene are deleted. In order to define more precisely the EBV-susceptible B cells, we sorted subpopulations of B cells on the basis of their cell surface Ig (sIg) isotypes, infected them with EBV, and determined which isotypes they could produce following transformation. Most precursors of IgM-producing plasma cells expressed both IgM and IgD on their surface, while a minority expressed IgM alone. Some B cell precursors of IgG- and IgA-producing cells also expressed sIgM, but surprisingly none expressed IgD. Those precursors of IgG and IgA producers, which bore sIgM, expressed it in relatively low levels, whereas B cells expressing high levels of sIgM were incapable of generating IgG and IgA producers. All of the precursors of IgG and IgA plasma cells expressed these isotypes on their cell surface. Interestingly, precursor B cells capable of producing the IgG3 and IgA2 subclasses could be respectively enriched on the basis of the presence or absence of cell sIgM. These results demonstrate the isotype precommitment of EBV-transformable B cells. They further suggest that residual IgM is transiently expressed on the surface of the IgG- and IgA-committed B cell precursors, whereas sIgD expression is extinguished earlier in the process of isotype switching via CH gene deletion.

B-Lymphocyte Subsets↗
PubMed1991

Reticular cells in peripheral lymphoid tissues express the phosphatidylinositol-linked BP-3 antigen.

The murine BP-3 antigen was initially described as a variably glycosylated cell surface protein of Mr 38,000 to 48,000 on lymphoid and myeloid cells. In the present experiments we found that this antigen is released from the surface of pre-B cells and macrophages by treatment with phosphatidylinositol-specific phospholipase C (PI-PLC), suggesting a glycosyl-phosphatidylinositol (GPI) linkage with the plasma membrane. When the tissue distribution of the BP-3-reactive cells was examined by immunohistology, high levels of the antigen were observed on brush borders of the intestinal epithelial cells, within collecting tubules of the kidney and on a subpopulation of reticular cells located on lymph nodes. Peyer's patches and the white pulp areas of the spleen. In contrast, reticular cells located in the thymus, bone marrow and splenic red pulp did not express the BP-3 antigen. Ontogenic studies revealed that BP-3 was expressed by the reticular cells in peripheral lymphoid tissues in the neonatal period near the time of lymphocyte immigration into these organs. BP-3+ reticular cells were observed in the collapsed periarterial lymphatic sheaths of adult mice depleted of T and B cells by cyclophosphamide treatment and in mice with severe combined immunodeficiency (scid), indicating that development of this reticular network is lymphocyte independent. The BP-3 antigen on the splenic reticular cells was also GPI anchored but its glycosylation pattern differed from that of the BP-3 molecules on pre-B cells. A specific subpopulation of reticular cells is thus marked by the BP-3 antigen, and the distribution and biochemical properties of the molecule make it an attractive candidate for a role in lymphocyte-stromal interactions in the peripheral lymphoid tissues.

Aging↗
PubMed1991

The implementation of ab initio quantum chemistry calculations on transporters.

The RHF and geometry optimization sections of the ab initio quantum chemistry code, GAMESS, have been optimized for a network of parallel microprocessors, Inmos T800-20 transputers, using both indirect and direct SCF techniques. The results indicate great scope for implementation of such codes on small parallel computer systems, very high efficiencies having been achieved, particularly in the cases of direct SCF and geometry optimization with large basis sets. The work, although performed upon one particular parallel system, the Meiko Computing Surface, is applicable to a wide range of parallel systems with both shared and distributed memory.

Computers↗
PubMed1991

Flow cytometric analysis of T-lymphocyte subsets in cats.

We report a rapid, reliable method for the immunophenotype analysis of feline lymphocytes. Fluorescein isothiocyanate (FITC) conjugated to murine monoclonal antibodies f43, Fel 7 and fCD8 was used to identify phenotypes corresponding to feline T-cells, CD4+ T cells and CD8+ T cells. For isolation of white blood cells, whole blood lysis was faster, less variable and required much less sample than density gradient separation. To identify feline CD4+ and CD8+ cells simultaneously, directly conjugated FITC-fCD8 and phycoerythrin (PE) fCD4 (Fel 7) were used in two-color analysis. The two T cell sub-populations were non-overlapping. Dual-label and single-label values were not significantly different. Mean lymphocyte subset percentages in conventional and specific-pathogen-free (SPF) cats did not differ significantly. These values were: pan T lymphocytes (f43), 54.8%, CD4+ cells (Fel 7), 33.9%, and CD8+ cells (fCD8), 19.1%. Mean CD4/CD8 ratio was 1.9 in normal cats; the range was 1.2-2.6.

Animals↗