Fig. 5.
(a–c) Surface IgG on the autoreactive B cell clones is responsible for binding and internalization of GAD65 and (d) efficient presentation of the endocytosed antigen to TCLs. Inhibition of binding of Alexa Fluor-GAD65 (1 µg/ml) with polyclonal anti-human IgG antibody in (a) DPA cells, (b) DPC cells and (c) DPD cells. The results are expressed as percentage mean fluorescence intensity (MFI), with 100% being represented by the binding of the Alexa Fluor-GAD65 in the absence of any competitor. (d) Inhibition by DPA cells as APC for presentation of GAD65 to TCL 6/7 by antihuman IgG F(ab′)2, demonstrating the crucial importance of surface IgG in binding the antigen for internalization and processing. The data represent the results of three experiments. The error bars show the standard error mean (s.e.m.) of triplicate cultures.