CYTOTOXIC ACTIVITY IN CHILDREN WITH INSULIN-DEPENDENT DIABETES-MELLITUS

We determined the percentage of circulating natural killer (NK) cells, using the monoclonal antibodies anti-CD57 and anti-CD16, NK cytotoxic activity (lytic units/10(6)) and lymphokine-activated killer (LAK) ac tivity in 25 IDDM patients aged 3-23 years, 12 with disease for <1 yea r (Group I) and 13 with disease for >3 years (Group II). Nine age-matc hed healthy subjects served as controls. The percentage of CD57+ cells was similar in IDDM patients and controls, while the percentage of CD 16+ cells was lower in IDDM patients (P<0.05) than in controls. NK cel l cytotoxic activity was lower in IDDM patients than in controls (P<0. 01), in Group I and II compared with controls (P<0.005). LAK activity was similar in IDDM patients and in controls. No correlation was found between NK cytotoxic activity and metabolic control, HLA typing, whil e a negative correlation was found between NK cytotoxic activity and i nsulin requirement (P<0.05). The decreased NK cytotoxic activity obser ved in our patients, in particular in long-standing diabetics, with no rmal NK cell number, could be due to a qualitative defect of the NK ce lls, or to a deficient IL-2 and/or TNF-alpha production, or to a immun omodulatory or immunosuppressing effect of insulin.