MONOKINE-PRODUCING CELLS PREDOMINATE IN THE RECRUITMENT PHASE OF NOD INSULITIS WHILE CELLS PRODUCING TH1-TYPE CYTOKINES CHARACTERIZE THE EFFECTOR PHASE

Cells infiltrating the Langerhans' islets of prediabetic NOD females w ere isolated from 6 weeks to 6 months of age. These cells were assayed at a single-cell level far production of eight different cytokines by intracellular immunofluorescent staining. Quiescent in vivo preactiva ted cells were detected by in vitro stimulation with PMA and ionomycin for 4 h. The cell recruitment phase, between 6 and 12 weeks of age, i s predominated by production of the monokines IL-1 alpha, IL-6, and TN F. After stimulation IFN-gamma and occasional IL-10 and GM-CSF produci ng cells could also be observed. This cytokine pattern occurs simultan eously with increasing insulitis, and we suggest that these cytokines are important in attracting inflammatory cells to the islets and maint aining the inflammatory state. A high frequency of endocrine cells pro ducing IL-6 during this period may denote a stress response caused by initial beta-cell destruction due to cytokines released by the inflamm atory cells. During the effector phase, between 4 and 6 months, there is a characteristic Th1 cytokine profile with lymphocytes producing IL -2, IFN-gamma and TNF, supposedly TNF-beta. No IL-4 production could b e detected and IL-10 was very rarely found, indicating the absence of a Th2 response. Our findings show that the effector phase in NOD insul itis is a Th1 rather than a Th2-mediated event. We also demonstrate th at cytokines that may cause initial tissue destruction are produced du ring the recruitment of inflammatory cells. (C) 1997 Academic Press Li mited.