Spontaneous and lectin-dependent cellular cytotoxicity by lymphocyte subpopulations against cell lines susceptible or resistant to spontaneous cytotoxicity.

In the present study we have investigated whether cell lines, which are resistant to spontaneous cytotoxicity, can be killed by lectin-dependent cellular cytotoxicity (LDCC), the expression of EAC (7S) receptors on LDCC effector cells, and the relationship between spontaneous cytotoxicity and LDCC when EAC (7S) receptor-positive or -negative subpopulations are tested against different target cell lines. We found that target cells which are resistant to spontaneous cytotoxicity can, indeed, be killed by LDCC, and that there is an inverse relationship between spontaneous cytotoxicity and LDCC, both when unfractionated lymphocytes were tested against different target cells and when fractionated cells were tested against cell lines highly susceptible to spontaneous cytotoxicity. The implications of these findings, in relation to the relative specificity of the spontaneous cytotoxicity system, are discussed.