IgM antibody to Treponema pallidum in cerebrospinal fluid of infants with congenital syphilis

* Objectives.--To characterize the neonatal IgG and IgM response to specific Treponema pallidum antigens in the cerebrospinal fluid (CSF) of infants with congenital syphilis. Design.--Cross-sectional survey. Setting.--Newborn nursery and neonatal intensive care unit of a county hospital in Dallas, Tex. Participants.--Twenty-one infants born to mothers with reactive serologic tests for syphilis were enrolled. Group 1 consisted of six infants with clinical and laboratory evidence of congenital syphilis; group 2, six asymptomatic infants born to mothers with untreated syphilis; and group 3, nine asymptomatic infants whose mothers were treated for syphilis before delivery. Selection Procedures.--Random sample. Measurements and Results.--Immunoblotting was used to examine the IgM and IgG reactivities of neonatal serum and CSF against T pallidum antigens. Among serum samples of all group 1 infants, a specific IgM response to T pallidum antigens with apparent molecular masses of 47, 45, and 17 kd was observed. Cerebrospinal fluid IgM reactivity to a 47-kd antigen of T pallidum was seen in four group 1 infants. Serum samples from two group 2 and three group 3 infants demonstrated IgM reactivity against the 47-kd antigen and, in some cases, against the 45-kd antigen of T pallidum. None of 15 group 2 and 3 infants had a positive CSF IgM immunoblot result. The IgG reactivity in CSF was similar in the three groups and was directed against T pallidum antigens with apparent molecular masses of 72, 59, 47, 45, 42, 37, 34, 17, and 15 kd. Conclusions.--A specific IgM response to T pallidum antigens, particularly the 47-kd antigen, was detected in the CSF of some infants with clinical and laboratory evidence of congenital syphilis. The potential usefulness of this test for the diagnosis of congenital neurosyphilis merits further study. (AJDC. 1992;146:1171-1175)