IgM rheumatoid factor in congenital syphilis: associations with clinical and laboratory findings.

IgM rheumatoid factor (RF), measured by means of an ELISA, was detected in 92% of infants with congenital syphilis. Elevated levels were found to correlate with liver and renal involvement as well as the extent of the disease (P less than 0.05). In addition, levels of circulating immune complexes were closely related to the RF concentration (P less than 0.001). Following treatment of the infants both RF levels and VDRL titres declined at a similar rate (P less than 0.001). These findings indicated a close relationship between the disease process and IgM RF levels. It is postulated that IgM RF may add to immune complex deposition and exacerbate tissue damage in congenital syphilis.