DEMONSTRATION OF A T-H1 CYTOKINE PROFILE IN THE LATE-PHASE OF NOD INSULITIS

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 for production of eight different cytokines by intracellular immunofluorescent staining, By in vitro stimulation wit h PMA and ionomycin for 4 hours the method is enhanced also to detect in vivo preactivated cells, During the early phase of insulitis from 6 to 12 weeks of age, mainly the monokines IL-1 alpha, IL-6, and TNF we re detected, After stimulation, also IFN-gamma and low numbers of IL-1 0 and GM-CSF producing cells could be observed, but no IL-2 or IL-4 wa s seen, This cytokine pattern correlates with an increasing insulitis, and we suggest that these cytokines are important in attracting infla mmatory cells to the islets, and may cause initial beta-cell destructi on, During a later phase, between 4 and 6 months, there is a character istic T-H1 cytokine profile with production of IL-2 and IFN-gamma occu rring after stimulation, as well as lymphocytes producing TNF, suppose dly TNF-beta. During this period IL-10 was very rarely observed, and n o IL-4 production could be found throughout the study, This indicates the absence of a T-H2 cytokine profile in this lesion, In addition IL- 6 production occurs in high frequencies at all ages, also in endocrine islet cells, We interpret this as a stress response caused by the inf lammatory lesion, Our findings show that the effector phase in NOD ins ulitis is T-H1 rather than T-H2 mediated. We also demonstrate that cyt okines, that may cause initial tissue destruction, are produced during the recruitment of inflammatory cells.