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T Crepaldi

Publications and source records attributed to T Crepaldi.

At least 37 records · Page 2Linked to original sources
PubMed1986

Equine T lymphocytes express MHC class II antigens.

Six anti-HLA class II mouse monoclonal antibodies (mAbs) were used in conjunction with a rat monoclonal antibody raised against horse lymphocytes to define class II major histocompatibility complex (MHC) molecules in the horse. By utilizing an ELISA assay and complement dependent lymphocytotoxicity assay, five out of the six anti-HLA class II antibodies and the rat anti-horse monoclonal antibody were found to react with a high percentage of peripheral blood lymphocytes. Flow cytometry demonstrated a variable antigen density on peripheral blood lymphocytes and clear evidence for expression by lymphocytes that carried no detectable surface immunoglobulin. None of the antibodies reacted with equine platelets. The mAbs immunoprecipitated an antigenic complex of Mr 29,000-33,000 from horse lymphocytes. It appears that the distribution of MHC class II antigens in the horse is different from that in man but is similar to that in the dog, since MHC class II antigens are expressed on resting peripheral blood lymphocytes which lack membrane-bound immunoglobulins. Correlations between the distribution of MHC class II antigens on lymphocyte subpopulations and their role in immunological phenomena may contribute to our understanding of the functional properties of these molecules.

Animals↗
PubMed1985

Further antigenic determinants on HLA-A molecules.

Monoclonal antibodies detect a new polymorphic antigenic determinant shared by HLA-A2, 3, 28, 29, 30, 31 and w33. This was demonstrated by population and family studies, including an HLA-A,B recombinant family, and by lysostrip experiments. Competition experiments, measuring the binding of 125I labelled MoAbs to B lymphoblastoid cell lines coated with anti-HLA conventional alloantisera and MoAbs showed that this new epitope is spatially distant from other known epitopes of A3 molecules and from monomorphic and polymorphic determinants of A2 molecules detected by monoclonal antibodies. On the other hand, anti-HLA-A2 polyclonal alloantisera are able to inhibit binding.

Antibodies, Monoclonal↗
PubMed1985

The monoclonal antibody AC1.59 defines a new polymorphic determinant on HLA-DR molecules.

2-dimensional gel electrophoresis analysis and sequential immunoprecipitation studies have shown that the monoclonal antibody (MoAb) AC1.59 recognizes a gene product of the HLA-DR locus. The determinant defined by the MoAb AC-1.59 has an unusual distribution on HLA-DR allospecificities, since it is expressed by HLA-DR1, DRw8, DRw9 antigens and by subtypes of HLA-DRw6 and HLA-DR4 antigens. In the latter allospecificity the expression of the MoAb AC1.59 defined determinant correlates with the cellularly defined HLA-Dw4 alloantigen. The present investigation provides evidence of serological heterogeneity within HLA-DR alloantigens. Furthermore these results suggest that monoclonal antibodies can sharpen the discriminatory power of serological assays to dissect the heterogeneity and complexity of HLA-DR alloantigens.

Antibodies, Monoclonal↗
PubMed1985

Identification of anti-DQ alloantisera correlated with DR5.

Using classical serological methods, we have been able to distinguish anti-HLA-DR from anti-DQ antibodies. The specificity of alloantisera for DQ could be identified on the basis of differential reactivity against B cell and monocyte-enriched leucocyte suspensions and lack of inhibition of cytotoxicity by anti-DR monoclonal antibodies. Some alloantisera, whose reactivity was significantly correlated with DR5, were found to exhibit these characteristics. The suggestion that they recognize DQ specificities in linkage disequilibrium with DR5 was supported by immunochemical analysis.

Antibodies, Monoclonal↗
PubMed1982

Characterization by monoclonal antibodies of lymphocyte subsets present in B-enriched suspensions.

B lymphocyte enriched suspensions isolated by E rosette depletion (E-cells) or by nylon fiber adherence (adherent cells) were identified by their cellular composition using different T and B cell markers (SIg,E receptor, T3, T4, T8 and Ia-like antigens). The cells were isolated from peripheral blood both of healthy donors and uremic dialysis patients. A variable proportion of non-B cells was found in some preparations. This contaminant was represented mainly by Null cells in E-lymphocyte suspensions and by T cells in the adherent population. Contaminating T lymphocytes were most frequently found in adherent cell preparations from uremic individuals and appeared to be an heterogeneous population including variable proportions of T4, T8 and Ia positive T cells. A significant increase of T8+ cells and a decrease of the ratio T4/T8 was seen among adherent T cells as compared to the normal distribution among T peripheral lymphocytes.

Antibodies, Monoclonal↗
PubMed1982

Inhibition of DNA replication and growth of several human and murine neoplastic cells by aphidicolin without detectable effect upon synthesis of immunoglobulins and HLA antigens.

Aphidicolin inhibits DNA replication and growth of all tested human and murine neoplastic cells including leukemic T- and B-lymphocytes and melanocarcinoma cells. The concentration of aphidicolin causing 50% inhibition of DNA synthesis in all of the tested neoplastic cell lines is similar to that necessary to inhibit DNA synthesis in HeLa cells by 50%. The mechanism of inhibition of DNA synthesis in neoplastic cells is again due to the inhibition of DNA polymerase alpha by aphidicolin. Aphidicolin at a concentration 100 times higher than that causing 50% inhibition of DNA synthesis and cell growth had no effect on total protein synthesis, on the secretion of immunoglobulins, or on the expression of HLA antigens which are involved in relevant phenomena of the immune response.

Animals↗
PubMed1981

A xenogeneic monoclonal antibody recognizing specificities controlled by HLA-A and B alleles.

In the present paper one reagent among the many prepared has been carefully studied. It is a xenogeneic monoclonal antibody, F10.13/13, obtained by immunizing mice with human peripheral blood lymphocytes. The splenocytes of the immunized mice were fused with a murine were fused with a murine myeloma and the supernatants of the resulting Ig-secreting hybridomas were tested against appropriate targets. --F10.13/13 behaves in a very peculiar manner from the serological point of view and we think that it reacts with maximal affinity with an epitope expressed most strongly on HLA glycoproteins controlled by genes B8, B7, and Aw19.

Alleles↗
PubMedDate not supplied

Expression of HLA class I antigens in human tumors and their involvement in tumor growth.

A decreased expression of major histocompatibility complex (MHC) class I antigens is a common feature of many experimental and human tumors and can often be correlated with malignancy grade. In fact, reduction of class I antigens is associated in most tumors with an enhanced ability to elude immune surveillance. Loss of HLA-A,B,C antigens ranges from a decrease in the percentage of A,B,C-positive cells to selective loss of particular antigens and total loss of class I molecule expression. In man, this has been documented in melanomas, carcinomas, lymphomas, neuroblastoma and acute leukemias. The reduction in membrane antigens is generally associated with a parallel fall in immunoprecipitable intracellular proteins and the corresponding mRNAs in the absence of structural changes in the coding genes. The literature concerning the above mentioned topics is reviewed and discussed.

Genes, MHC Class I↗
PubMedDate not supplied

Alloantisera with apparent HLA-A specificity reacting only against phytohemagglutinin-activated cells.

Seven alloantisera were selected showing the following characteristics: after platelet absorption they were positive with PHA-activated cells and negative with resting T and B lymphocytes from the same donors; this reactivity could be blocked by pretreatment of cells with a turkey anti-human beta 2-microglobulin serum and was not completely removed by further absorption with high doses of pooled platelets or with T or B lymphocytes from the positive donors; the reactivity of some of these antisera correlated with HLA-A antigens in a panel of PHA-activated cells and segregated with HLA haplotypes in families. It is still to be proven if the HLA determinants recognized on PHA-activated cells by these antisera are new epitopes of A,B,C molecules appearing upon activation or if they are carried by products of a new polymorphic locus linked to the HLA system.

B-Lymphocytes↗
PubMedDate not supplied

New HLA class I-like alloantigens expressed on blast cells.

New beta 2-microglobulin (beta 2-m)-associated, HLA-linked alloantigens, selectively expressed on phytohaemagglutinin (PHA)-activated lymphocytes, were identified using human alloantisera. Reactivity of the antisera against activated cells correlated with HLA-A2, A10 and A28 specificities. The new alloantigens were undetectable on peripheral blood mononuclear cells, B lymphocytes and platelets using either the lymphocytotoxicity or the absorption techniques, and appeared on lymphocytes upon PHA activation, with time-dependent kinetics. They were found on some, but not all, acute leukaemias of B, T and myeloid origin, being absent from chronic B lymphocytic leukaemias. The presence of the new beta 2-microglobulin-associated allospecificities was not correlated with the quantity of classical class I antigens present, as analysed on different cell types by flow cytometry. Thus, these antigenic determinants appear to be different from the classical HLA class I antigens and could be the human counterpart of the murine Qa system or of the second H-2K gene.

B-Lymphocytes↗
PubMedDate not supplied

[Preliminary serological analysis for identification of direct monoclonal antibodies against surface structures of HLA typed human lymphocytes].

The following schedule has been applied to the selection and preliminary serological definition of monoclonal antibodies against HLA controlled antigenic structures of human lymphocyte surface: 1) identification of antibodies reactive against the immunizing cells by means of indirect radiobinding technique and complement-dependent lymphocytotoxicity; 2) analysis of the pattern of reaction against a panel of T and B lymphocytes purified from peripheral blood of HLA typed donors. The reaction has been performed also against lymphocytes pretreated with anti-human-beta 2 microglobulin antibodies. Thus monomorphic and polymorphic monoclonal antibodies, directed against beta 2 microglobulin associated or not associated antigens, can be identified. The importance of the complement pool and of antibody avidity in the lymphocytotoxicity reaction mediated by monoclonal antibodies, is evaluated.

Antibodies↗