The enhancement of cultured spontaneous cytotoxic T cells from normal and athymic (nu/nu) mice.

Subsets of natural killer cells may be characterised by the target cell profile, cell surface markers and the effect of growth factors on the production of effector cells. The subset which appears in primary cultures (spontaneous or natural T killer cells) is enhanced by the supernatants of Con A-stimulated rat spleen cultures. The enhancement can be attributed to an increased number of clones rather than an expansion of clone size in 5-day cultures. With semi-purified IL-2 preparations, clones of spontaneous cytotoxic cells are also detectable in nu/nu spleen cultures. These results suggest such spontaneous cytotoxicity is a general phenomenon within cytotoxic responses.