Cold-reactive lymphocytotoxic antibodies are present in the serum of most patients with systemic lupus erythematosus (SLE) (Mittal et al., 1970; Terasaki et al., 1970). They appear to be equally cytotoxic for autologous and heterologous lymphocytes (Stastny and Ziff, 1971). Studies of the nature of these antibodies showed that their cytotoxic effect is temperature-dependent and maximal at 15°C,...