Does protease inhibitor inhibit complement activation caused by the immune complex associated with islet cell surface antibody?
Sera containing islet cell surface antibody were obtained from seven children with insulin-dependent diabetes mellitus soon after the onset of disease. After incubation of 51Cr-labelled rat islet cells with islet cell surface antibody, human AB-type serum with or without nafamostat mesylate was added before further incubation. Radioactivity in the supernatant was measured to determine complement-dependent antibody-mediated cytotoxicity. Cytotoxicity in untreated sera [mean (+/- SD) 19.4 +/- 4.0%] was significantly (P less than 0.001) inhibited by ethyleneglycoltetraacetic acid (EGTA) (7.1 +/- 4.9%), ethylenediaminetetraacetic acid (EDTA) (2.5 +/- 0.9%) and nafamostat mesylate (2.8 +/- 1.8%). Cytotoxicity of nafamostat mesylate-treated serum was significantly (P less than 0.05) lower than that of EGTA-treated serum but not significantly different from that of EDTA-treated serum. There was no difference in cytotoxicity between nafamostat mesylate-treated and untreated, inactivated human
