Heterogeneity of Monoclonal Antibodies against Pancreatic Beta Cells

Summary

Sixteen murine hybridoma-secreting monoclonal antibodies against pancreatic islet cell surface antigens (mc-ICSA) have been produced by the cell fusion technique using Splenocytes from xenogeneic islet cell- or RIN cell-immunized Balb/c mice. In addition, some mice were auto-immunized by subdiabetogenic doses of the beta cell toxin streptozotocin in combination with complete Freund's adjuvant. Isotyping of the mc-ICSA revealed that 13 of the antibodies belong to the class IgM, and 3 to the subclass IgG1.

The specificity of these mc-ICSA has been detected by means of the indirect immunofluorescent technique using primary rat islet cells suspensions, following a procedure of double immunostaining for pancreatic insulin and glucagon. Furthermore, the cross reactivity of these mc-ICSA was studied using endothelial, neuroblastoma and fibroblast cell lines and primary rat splenocytes. One out of the 10 mc-ICSA tested was alpha cell-specific, 2 were beta cell-specific and 7 out of 10 were reactive with both alpha and beta cells. Eleven mc-ICSA showed no cross-reactivity with the 5 other cell types tested.

The binding of one mc-ICSA was blocked by 6 of the ICSA-positive human sera which were tested, suggesting that this monoclonal recognizes the same antigenic determinant. The same mc-ICSA diminished the glucose- and arginine-stimulated insulin secretion of isolated rat islets.

Key words

Murine monoclonal antibodies - Pancreatic islet cells - Cross reactivity - Cell lines - Pancreatic islets - Insulin secretion