How can a viral infection produce a chronic auto-immune disorder?

In ITP it is believed that the antibodies (IgG) that are produced in response to certain infections may become attached to a region of the platelet surface called glycoprotein IIb-IIIa or perhaps glycoprotein Ib-IX.

Under certain conditions that are poorly understood the IgG antibodies or the immune complex (antibody-virus complex or antibody-platelet complex) generated by an infection may activate certain cells of the Immune system (CD4 cells).

These activated CD4 cells will clone themselves and the clones will also express anti-IIb/IIIa or anti-Ib/IX glycoprotein.

These CD4 clones may thereby stimulate B cells to produce additional anti-IIb/IIIa or anti-Ib/IX IgG antibodies.