Lyme IgG Band 18 details

This is one of the individual protein bands checked on a Lyme disease confirmatory Western blot (immunoblot) test, IgG class, run after an initial antibody screen comes back positive or unclear. Each band represents antibodies against a different protein from the Lyme-causing bacterium, and labs use an established scoring system (a minimum number of positive bands out of a defined panel) to determine whether the overall IgG Western blot counts as positive. IgG bands like this one tend to develop later in the course of infection and, once present, can persist for years — even after successful treatment — so results are always interpreted alongside your symptoms and history of possible tick exposure.