Denis M. Callewaert

Spontaneous cytotoxicity of human lymphoblast cell lines mediated by normal peripheral blood lymphocytes. I. Differential susceptibility of T-versus B-cell lines.

Abstract Human lymphoblast cell lines of B- and T-cell origin have been tested for their ability to serve as targets in a 4-hr 51Cr release microcytotoxicity assay using normal human peripheral blood lymphocytes as effector cells. Cell lines of T-cell origin were susceptible to lysis in this assay by effector lymphocytes from all normal donors tested. Cell lines of B-cell origin were repeatably lysed by normal lymphocytes from some, but not all donors. Spontaneous cytotoxicity of B-cell lines, when observed, was also quantitatively less than was obtained using T-cell lines as targets. One cell line (RPMI-7666), of B-cell origin, was not susceptible to spontaneous cytotoxicity by almost all of the normal lymphocyte effectors tested. Lymphocytes from patients with acute lymphoblastic leukemia in remission were less capable of effecting lysis in this assay.

Spontaneous cytotoxicity of cultured human cell lines mediated by normal peripheral blood lymphocytes: II. Specificity for target antigens

Abstract The specificity of human spontaneous cell-mediated cytotoxicity (SCMC) of cultured cell lines has been investigated using both direct cytotoxicity and inhibition of cytotoxicity in large “checkerboard” type experiments. By direct cytotoxicity significant positive correlations of lysis were found between two autologous T and B lymphoblast cell lines as well as between allogeneic T and B cell lines. These results indicate the expression by these cell lines of either common or universally recognized sets of SCMC target antigens. Cross-inhibition studies confirmed the existence of SCMC antigens common to different cell lines. However, SCMC inhibition by unlabeled cells homologous to the 51Cr-labeled target cells was generally equal to or greater than that produced by other cell lines. This suggests that although some SCMC target antigens are common to many different cell types, each cell line expresses a characteristic set of these antigens.

Stimulation in the mixed leukocyte culture and generation of effector cells in cell mediated lympholysis by a human T lymphoblast cell line

Abstract The lymphoblast cell lines CCRF-SB possessing B cell surface markers and CCRF-HSB-2 possessing T cell surface markers, both derived from the same individual, were tested for their ability to stimulate in the mixed leukocyte culture (MLC) and their ability to generate effector cells in cell mediated lympholysis (CML). Both the T and B cell lines were capable of stimulating human peripheral blood lymphocytes, however, the T cell line required four times as many cells for an equivalent response. Generation of effector cells in CML was achieved when both the T and B cell lines were used as stimulator cells but the T cell line was capable of generating a greater degree of 51 Cr release.