Alteration in lymphocyte population and humoral immune response in type 2 diabetic Goto-Kakizaki rats

AimsProinflammatory cytokine production by a skewed T cell compartment has been shown to be elevated in patients with type 2 diabetes (T2D). However, it is unknown whether humoral immune response controlled by lymphocytes is altered in T2D.Main methodsLymphocyte populations and immunoglobulin production were investigated in Goto–Kakizaki (G–K) rat, which is a genetic experimental model for T2D, and Wistar rat as a control. Each lymphocyte population was analyzed using flow cytometry. Immunoglobulin in plasma was measured before and after immunization with ovalbumin. The immunoglobulin subclasses and ovalbumin-specific immunoglobulins were measured by enzyme-immunoassay. Effects of improvement in hyperglycemia of G–K rats by chronic diet restriction on lymphocyte populations were also investigated.Key findingsT/B lymphocyte ratios in blood and spleen from the G–K rats were significantly higher than those from the Wistar rats. The difference in the T/B cell ratio in blood of the G–K and Wistar rats was not affected by the diet restriction and the immunization. The ability of immunoglobulin production in G–K rats was comparable to that in Wistar rats, while the levels of natural IgM and ovalbumin-specific IgG2a were higher in plasma from the G–K rats than in plasma from the Wistar rats.SignificanceSince helper T cell type 2 (Th2) is known to regulate the class switch to IgG2a in rats, the results of this study suggest that G–K rats are characterized as immunologically Th2 dominant, resulting in increases in natural IgM and T/B cell ratio.