Abnormal lymphocyte function precedes hyperglycaemia in mice treated with multiple low doses of streptozotocin

To investigate early immunological disturbances at the onset of diabetes, lymphocyte function and islet cell surface antibodies were studied in streptozotocin-treated C57BL/10 and B10.BR mice. In C57BL/10 mice, streptozotocin given in multiple low doses depressed lymphoblastic transformation to phytohaemagglutinin and pokeweed mitogen, but not to concanavalin A on day 6 after the first administration. On day 20, the transformation remained suppressed with phytohaemagglutinin, but recovered to the control level with pokeweed mitogen. In the early phase after treatment, the islet cell surface antibodies were elevated and then declined. Single high dose administration depressed responses to phytohaemagglutinin with no detectable islet cell surface antibodies. In B10.BR mice transformations to pokeweed mitogen and concanavalin A were suppressed in the early phase. The strain of mice may be a factor to be considered. Thus, it was suggested that the deterioration of immunological function with the formation of islet cell surface antibodies preceded the onset of hyperglycaemia in mice treated with multiple low doses of streptozotocin.