Impaired Mitogen-Induced Expression of High-Affinity Interleukin 2 Receptors on Spleen Cells From NOD/Shi/Kbe Mice

Abstract

The immune abnormalities of NOD mice, a model of human type I (insulin-dependent) diabetes, have been postulated to be T-lymphocyte dependent. We measured responsiveness to exogenous interleukin 2 (IL-2) and IL-2 production in spleen mononuclear cells from female NOD/Shi/Kbe mice after stimulating the cells with concanavalin A (ConA blasts) or phytohemagglutinin (PHA blasts). Exogenous IL-2 produced significantly lower proliferative responses in each blast from 3- and 10-wk-old NOD/Shi/Kbe mice than from control strains. IL-2 production in NOD/Shi/Kbe mice was inclined to decrease but not significantly compared with controls. Even sufficient amounts of recombinant IL-2 (rIL-2) or IL-1 (rIL-1), added with mitogens to the preculture medium, failed to provoke normal proliferative responses from NOD/Shi/Kbe mouse cells. To clarify the reason for this defect, we investigated the expression of IL-2 receptors (IL-2Rs) on mitogen-activated cells with anti-IL-2R monoclonal antibody (PC61) and radiolabeled IL-2. Cytofluorometry showed no significant difference between strains in the number of PC61+ ConA and PHA blasts. However, Scatchard analysis with 125I-labeled IL-2 showed that the number of high-affinity IL-2Rs (H-IL-2Rs), the mediators of the biological activity of IL-2, was decreased in NOD/Shi/Kbe mice compared with controls, whereas the number of low-affinity IL-2Rs (L-IL-2Rs) was not different. Separating the L3T4+ and Lyt-2+ populations of T lymphocytes by cell sorting showed both to be deficient in H-IL-2Rs.(ABSTRACT TRUNCATED AT 250 WORDS)