In the present study we have evaluated the expression of different beta-cell markers, islet molecules and auto-
antigens relevant in diabetes autoimmunity by a human
insulinoma cell line (CM) in order to define its similarities with native beta cells and to discover whether it could be considered as a model for studies on immunological aspects of
Type 1 diabetes. First, the positivity of the CM cell line for known markers of neuroendocrine derivation was determined by means of immunocytochemical analysis using different anti-islet
monoclonal antibodies including A2B5 and 3G5 reacting with islet
gangliosides, and HISL19 binding to an islet
glycoprotein. Secondly, the expression and characteristics of
glutamic acid decarboxylase (GAD) and of
GM2-1 ganglioside, both known to be islet
autoantigens in diabetes autoimmunity and expressed by human native beta cells, were investigated in the CM cell line. The pattern of
ganglioside expression in comparison to that of native beta cells was also evaluated. Thirdly, the binding of diabetic sera to CM cells reacting with islet cytoplasmic
antigens (ICA) was studied by immunohistochemistry. The results of this study showed that beta cell markers identified by anti-islet
monoclonal antibodies A2B5, 3G5 and HISL-19 are expressed by CM cells; similarly, islet molecules such as GAD and
GM2-1 ganglioside are present and possess similar characteristics to those found in native beta cells; the pattern of expression of other
gangliosides by CM cells is also identical to human pancreatic islets; beta cell
autoantigen(s) reacting with
antibodies present in islet cell
antibodies (ICA) positive diabetic sera identified by ICA binding are also detectable in this
insulinoma cell line. We conclude that CM cells show close similarities to native beta cells with respect to the expression of neuro-endocrine markers, relevant beta cell
autoantigens in
Type 1 diabetes (GAD, GM2-1, ICA
antigen), and other
gangliosides. Therefore, this
insulinoma cell line may be considered as an ideal model for studies aimed at investigating autoimmune phenomena occurring in
Type 1 diabetes.