Cellular and molecular properties of an antigen-specific cytotoxic T lymphocyte line.

Two cytotoxic T cell lines of CBA/J mouse origin have been generated, cloned, and characterized. One of these, MTL2, is cytotoxic for cells carrying the H-2(d) haplotype, the other MTL3, for H-2(b). Two clones of MTL2 differ significantly from each other in the morphology of the cells, although not in cytotoxicity. One has a higher number of intracellular vacuoles, or vesicles, and shows more of the typical attaching structures to the growth surface ("spikes") compared with the other. Cross-reactivity with a third-party alloantigen is enhanced by adding Con A to the cytotoxicity assay, but there is no self-killing either with or without Con A. The T cell lines show no rearrangement in their immunoglobulin heavy chain J and C(mu) genes. Normal T cells are also not rearranged, apparently, but normal B lymphocytes have both of their heavy chain alleles altered. Finally, cloned MTL2 cells contain less than five molecules of mu (IgM heavy chain constant region) mRNA per cell.