[Quantitative determination of FTA abs IgM in different stages of syphilis before and after treatment].

The titres of treponemal specific IgM and IgG antibodies were determined by monospecific immunofluorescence (FTA abs IgM/IgG) on 191 sera from 107 patients with treated or untreated syphilis, at various stages and from 10 neonates born from seropositive mothers. IgM antitreponemal antibody was found in all cases of untreated syphilis but two neurosyphilis. After treatment the antibody usually disappeared within one year. However it persisted in three patients treated two years ago or more. When sera from these patients were fractionated by density gradient ultracentrifugation and examined for antitreponemal antibodies of the IgM classe (FTA abs IgM 19S) they never showed detectable concentrations of IgM. False reactive results as false non reactivity due to competitive inhibition, observed with FTA abs IgM can be eliminated after separation of immunoglobulins.