CD40LG and erythema multiforme: The aims of the study were (i) to identify the antigens which are reactive in patients with persistent anti-Borrelia IgM and in EM patients; (ii) to study cross-reactions to Borrelia-unrelated antigens; (iii) to examine whether the number and the improvement of reported symptoms are associated with enzyme-linked immunosorbent assay (ELISA) values; and (iv) to determine the frequency of antibiotic prescriptions in patients with persistent anti-Borrelia IgM.