Con A-induced suppressor cells in children with acute lymphoblastic leukaemia.

The function of Con A stimulation was investigated in patients with ALL in remission and in patients with ALL in the acute phase of the disease as compared to healthy controls. Suppression of the Con A response brought about by autologous Con A-activated cells was significantly lower in ALL patients in remission (mean value 29.33%) and in the acute phase (mean value 10%) than in the controls (mean value 64.86%). Suppression of the Con A stimulation of control lymphocytes by Con A-activated homologous cells of ALL patients had a mean value of 51.65%. This was significantly higher than the suppression obtained by the same ALL cells in the autologous system and of the same order of magnitude as the suppression obtained by control Con A-activated cells on control Con A stimulation (57.67%). Suppression of the Con a response of ALL lymphocytes produced by control Con A-activated cells was 23.17% and comparable to healthy controls. These results demonstrate that the function of Con A-induced suppression is significantly lower in ALL patients. They further indicate that at least two cell types are involved in this kind of suppression in humans.