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Biomedical subjects

B E Chechik

Publications and source records attributed to B E Chechik.

At least 37 records · Page 2Linked to original sources
PubMed1980

Identification of human thymus-leukemia-associated antigen as a low-molecular-weight form of adenosine deaminase.

In the determination of whether human thymus-leukemia-associated antigen (HThy-L) is a low-molecular-weight form of adenosine deaminase (ADA), both HThy-L and ADA were found to have the same molecular weight of 45,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antigen and enzyme displayed a phenomenon of complete identity in immunodiffusion and a high degree of cross-reaction in a competitive radioimmunoassay for HThy-L or ADA. When tested for adenosine-deaminating activity, HThy-L was nearly as active as purified low-molecular-weight ADA from erythrocytes. However, HThy-L and ADA differed in their capacity to combine with the complexing protein isolated from human kidney. Apparently, HThy-L represents a thymic isoenzyme of ADA and is the first antigen to be associated with differentiation of hematopoietic cells for which a functional activity is established.

Adenosine Deaminase↗
PubMed1979

Radioimmunoassay for human thymus-leukemia-associated antigen.

A competitive radioimmunoprecipitation method was developed for the quantitation of human thymus-leukemia-associated antigen (HThy-L) isolated from human thymus tissue. Antisera to the antigen were raised by immunization of rabbits with purified fractions of HThy-L. The antigen was labeled with 125l by means of a modification of the lactoperoxidase technique and subjected to Sephadex G-100 gel filtration. Analysis of fractions eluted from this column by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two labeled components with apparent molecular weights of 45,000 and 25,000 daltons, respectively. Immunoprecipitation with anti-HThy-L antiserum demonstrated directly that the 45,000-dalton component carried HThy-L antigenicity. This fraction served as the source of labeled antigen in a competitive radioimmunoassay that permitted the detection of approximately 1 ng HThy-L. With the use of this assay, we confirmed quantitatively that the highest amounts of HThy-L were found in extracts of thymocytes, normal thymus tissues, and lymphoblasts for T-cell lines.

Animals↗
PubMed1979

Quantitation of human thymus-leukemia-associated antigen in established hematopoietic cell lines by radioimmunoassay.

A competitive radioimmunoassay for a saline-soluble human thymus-leukemia-associated antigen (HThy-L) was applied for quantitation of this antigen in leukemia and normal hematopoietic cell lines. Highly increased quantities of HThy-L were detected in all T-cell leukemia lines tested, regardless of the presence or absence of receptors for sheep erythrocytes. This elevated level of HThy-L in combination with high terminal deoxynucleotidyl transferase and adenosine deaminase activities and the presence of a T-lymphocyte-specific surface antigen appear to represent stable phenotypic characteristics of T-cell lines. Most normal B-cell lines had low quantities of HTy-L. The level of HThy-L was slightly elevated in a considerable number of lymphoma B-cell lines and in all non-T, non-B leukemia cell lines tested. No relationship existed between quantities of HThy-L and an expression of different surface immunoglobulin isotypes in B-cell lines. Low quantities of HThy-L were detected in leukemia myeloid and myeloma cell lines as well as in B-cell leukemia lines originating from patients with B-cells acute lymphoblastic leukemia. Apparently, the increased quantities of HThy-L in T-cell leukemia lines may be related to certain stages of T-cell differentiation at which leukemia cell transformation occurs.

Antigens, Neoplasm↗
PubMed1979

Quantitation of human thymus/leukemia-associated antigen by radioimmunoassay in different forms of leukemia.

Using a radioimmunoassay, increased levels of a human thymus/leukemia-associated antigen (HThy-L) have been detected in leukemic cells and plasma from most patients with E-rosette-positive acute lymphoblastic leukemia (ALL) and a number of patients with E-rosette-negative ALL, acute myeloblastic leukemia (AML), acute monomyelocytic leukemia (AMML), and acute undifferentiated leukemia (AVL). Low levels of HThy-L have been demonstrated in white cells from patients with chronic myelocytic leukemia (stable phase) and in mononuclear cells from patients with chronic lymphatic leukemia. The relationship between HThy-L and differentiation of hematopoietic cells is discussed.

Acute Disease↗
PubMed1978

Human thymus-leukemia-associated antigen: isolation and partial characterization.

Human thymus-leukemia-associated antigen (HThy-L), a saline-soluble antigen, was previously detected by immunodiffusion (but not on the cell surface) in significant quantity in extracts of normal thymocytes, cells from cultured T-cell lines, and erythrocyte-rosette-positive leukemia blasts. Two species of HThy-L were identified and isolated from normal human thymus tissue after extraction in tris buffer, ammonium sulfate fractionation, acid precipitation of inactive fractions, DEAE-cellulose (DE-52) chromatography, Sephadex G-100 gel filtration, and carboxymethyl-cellulose (CM-52) chromatography; On Sephadex G-100, both HThy-L species had a similar molecular weight (40,000--50,000), but they eluted in different positions on DE-52 and CM-52. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that each of the 2 HThy-L species contained 2 components with molecular weights of approximately 43,000 and 23,000. Further purification of HThy-L on Sephadex G-50 showed that the 43,000-dalton component possessed HThy-L activity.

Antibodies, Neoplasm↗
PubMed1976

Human thymus/leukemia-associated antigen in normal and leukemic cells.

A saline extractable human thymus/leukemia-associated antigen (HThy-L) has been detected in immunodiffusion using rabbit antisera raised to human thymus extracts. HThy-L was demonstrated in extracts of normal thymocytes, lymphocytes from E-rosetting T-cell lines and from the blast cells of patients with E-rosetting acute lymphoblastic leukemia. Extracts of leukemic cells from patients with acute myeloblastic leukemia and E-rosette-negative acute lymphoblastic leukemia contained significantly lower quantities of HThy-L. Only trace amounts of the antigen were detected in normal spleen tonsil, peripheral blood, bone marrow and PHA-induced lymphoblasts. HThy-L appears to be an antigen associated with the intrathymic differentiation of human T cells and a marker of leukemic cells in certain forms of acute leukemia.

Antigens, Neoplasm↗
PubMed1976

Leukaemia-associated antigen in serum of patients with acute lymphoblastic leukaemia.

A antigen (HThy-L) previously found in extracts of human thymocytes and leukalphaemic cells was detected in sera from four patients with E-rosette-positive untreated acute lymphoblastic leukalphaemia (A.L.L.) and one patient with previously treated acute myelogenous leukaemia (A.M.L.) The disappearance HYth-L angignaplhaemia with treatment was coindent with a decrease in the number of leukaemic blast cells in the peripheral blood. HThy-L antigen was not detected in the sera of the remaining twenty-one patients with E-rosette-negative A.L.L. and seven patients with A.M.L..

Adolescent↗