Lymphocytotoxic and phagocytotoxic activity in progressive systemic sclerosis.

Sera of 66 patients with progressive systemic sclerosis (PSS) were tested for cold and warm reacting lymphocytotoxins (LCT). Cold LCT were found in 30 (45%) patients, 18 of whom also had warm LCT. Warm LCT alone were found in 14 patients. Twenty-nine sera with cold LCT were tested and reacted with both peripheral B and T lymphocytes. There was predominant killing of B cells in 52% and of T cells in 14%. Ten cold LCT were absorbed to and eluted from peripheral blood lymphocytes. All eluates were cytotoxic to B and T cells; 1 killed predominantly T cells and 2 killed predominantly B cells. Clinical-laboratory and HLA correlations with cold LCT showed no significant differences between the LCT-positive group and the LCT-negative group. Granulocytotoxins were rare in PSS, but warm reacting monocytotoxins were found in 33 cases (57%). Crossreactivity of cytotoxins was tested using eluates from various cells. The majority of eluates from lymphocytes were cytotoxic against polymorphonuclears (PMN) and monocytes. Some eluates from PMN and from monocytes had lymphocytotoxic activity. This suggests existence of common antigenic determinants on various cells against which cytotoxins are directed.