Modelling of type 1 diabetes with monoclonal antibody ICA-1

In order to investigate the possible role of pancreatic beta-cell p(64-69) antigens in the development of diabetes type 1, a monoclonal antibody (ICA-1) to the 64-69 kDa antigen family was produced and characterized. Short-term (0.25 mg per rat, intraperitoneally, daily for 9 days) and prolonged (0.125 mg per rat, intraperitoneally, three times a week for 8 weeks) administration of ICA-1 to Wistar rats caused the development of a diabetes-like reaction characterized by moderate hyperglycaemia, markedly reduced pancreatic insulin content, and depressed insulin secretion. After 9 days, histological changes in the pancreas indicative of early insulitis were also observed. Continued ICA-1 treatment increased mononuclear infiltration of the islets and progressive beta-cell damage became evident. In order to confirm the insulin-dependent character of this early-stage diabetes induced by ICA-1, rats were injected with insulin in liposomes, whereupon normalization of serum insulin levels was observed together with a decrease in mononuclear infiltration. These results indicate that the 64-69 kDa antigen family is closely related to the hypothetical primary target protein that may play a role in the development of autoimmune beta-cell destruction.

Immunoreactivity of cultured pancreatic islet cells with monoclonal antibody ICA-1

The aim of the present study was to characterize the expression of the pancreatic beta cell antigen family with molecular masses of 64 to 69 kDa [p(64-69)]. This antigen family was detected by immunoreactivity with biotinylated monoclonal antibody (Mab) ICA-1, and Mab against insulin. The molecular masses of the antigens affinity-purified from islet cell lysates by ICA-1 were 64, 67, and 69 kDa. Detailed analysis of p(64-69) expression was carried out on cultured islet cells reassociated into clusters of islet-like structures. Cell-fluorescence image processing by computerized image analysis, combined with transmission and scanning electron microscopy, of cells labelled with Mab ICA-1 and immunogold revealed the localization of the 64-65 kDa antigen family on the beta cell surface and its grouping on microvilli and near areas of fusion of the insulin-containing beta granules with the plasma membrane. In view of the effect of ICA-1 on insulin release and its localization on the beta cell surface in immunoreactions it is proposed that the p(64-69) antigen family is involved in insulin secretion.