Figure 6.

Postulated interpretation of results. Normal islets are populated by three beta cell types displaying variations in PC1/3 expression. Alterations in PC1/3 expression occur in a subset of islets of autoantibody positive donors; the expression of the convertase in beta cells of these abnormal islets is homogeneous, is either high or low, and is characteristic for a pancreatic region. It is hypothesized that there is a gradual change in islet type during progression to type 1 diabetes from one containing three beta cell types with heterogeneous PC1/3 expression to a monotype with either high or low levels of the proconvertase. It is also proposed that the alteration in the expression of the enzyme results in a reduction of its enzymatic activity. Large circle: islet; small circles, beta cells. Shades of green in small circles indicate level of PC1/3 expression. Abbreviation: PC1/3, proprotein convertase 1/3.