Diagnostic use of very sensitive early-phase antigens, such as VlsE, which enable the detection of a specific IgG response very early on in the course of the infection, means specific IgM antibody findings as part of Lyme borreliosis diagnostics are playing an increasingly limited role, especially since the IgM detection exhibits a poorer overall specificity than the IgG detection [97], [98]. Here, CD40LG is linked to Lyme disease.