Decreased insulitis and blood glucose levels after injection of GAD-transduced lymphocytes into NOD mice.

Abstract

We used NOD mice to investigate the effects of injecting transduced lymphocytes on insulitis, nonfasting blood glucose levels, and immune responses. Syngeneic splenocytes were transduced with retroviral particles carrying a cDNA construct encoding the beta cell antigen glutamic acid decarboxylase (GAD65), a secreted form of GAD65 (SGAD55), or secreted alkaline phosphatase (SEAP) as a control antigen. Different multiplicities of infection (m.o.i.) were used with different constructs. Four-week-old NOD mice received intravenous injection of CD4(+) cells isolated from transduced splenocytes, and insulitis and blood glucose levels were determined at 10 weeks of age. No significant effects were observed with lymphocytes transduced with gad65 and sgad55 constructs at low m.o.i. By contrast, at high m.o.i., lymphocytes transduced with the sgad55 and seap constructs caused a decrease in insulitis and blood glucose levels and in insulitis alone, respectively. ELISA of anti-GAD antibody isotypes indicated that GAD-transduced lymphocytes induced similar Th2-like responses at all m.o.i. These results suggest that retroviral particles carrying sgad55 can be used for engineering cell vaccines for type 1 diabetes and provide further evidence that Th2-like responses induced by immunization may not always be a primary cause of diabetes suppression in NOD mice.