Establishment of apoptosis‐inducing monoclonal antibody 2D1 and 2D1‐resistant variants of human T cell lines

Abstract

A monoclonal antibody (mAb), 2D1(IgM), was identified for its anti‐proliferative effect on human T leukemia cell line, SUP‐T13. The cells bound with 2D1 showed DNA ladder patterns of oligonucleosomes, demonstrating apoptosis. Peripheral mononuclear cells activated by phytohemagglutinin or OKT3 induced expression of 2D1 antigen and were growth‐inhibited by the antibodies. Amsong the cell lines tested, T cell lines tended to be growth‐inhibited by the antibodies. Epstein‐Barr virus‐transformed B cells were reactive with 2D1, but were not growth‐inhibited by the antibodies. We established stable 2D1‐resistant variants LAC2D1R and JKT2D1R from the original SUP‐T13 and Jurkat T cell lines, respectively. These variant cells demonstrated phenotypes identical to the original cells, including reactivity to 2D1 and expression of cytoplasmic Bc1‐2 protein. The 2D1‐resistant cells were as sensitive as the original cells to the other apoptosis‐inducing stimuli, such as γ‐irradiation or calcium ionophore A23187. However, the 2D1‐resistant variants were also insensitive to anti‐Fas, another apoptosis‐inducing mAb. Binding of 2D1 was blocked by anti‐Fas mAb, suggesting that 2D1 reacts with an epitope of human Fas molecules. The present results demonstrate that a 2D1‐reactive, but not 2D 1‐sensitive, population may exist in highly 2D1‐sensitive human leukemia T cells and that pairs of 2D 1‐sensitive and 2D1‐resistant cells are useful in the biochemical analysis of Fas‐mediated apoptosis in human T cells.