Determination of rubella virus specific humoral and cell mediated immunity in pregnant women with negative or equivocal rubella specific IgG in routine screening.
BACKGROUND Immunity to rubella virus (RV) is commonly determined by measuring specific IgG (RV IgG) However, RV IgG results may be different and even discordant, depending on the assay used. Cell mediated immunity is not routinely investigated for diagnostic purposes. OBJECTIVES Our aim was to investigate humoral and cellular immunity of women with negative or equivocal RV IgG before, and after post partum vaccination. STUDY DESIGN A total of 186 pregnant women were included in the study. During pregnancy, humoral immunity was investigated with two RV IgG immunoassays, an immunoblot and a T cell mediated immunity test. In the post partum vaccination period, measuring RV IgM and RV IgG avidity allowed us to determine whether women raised a primary or a secondary immune response. RESULTS Before vaccination, 52.2% women, supposed to be susceptible, had positive anti E1 RV IgG indicating strong evidence of previous exposure to RV. All (100% pregant women who had a positive immunoblot before immunization raised a secondary immune response to vaccination, and 96.8% who had a negative immunoblot before immunization, raised a primary immune response to vaccination. All women who raised a primary immune response after vaccination had negative anti E1 RV IgG and negative cell mediated immunity. DISCUSSION These results indicate that individuals can have evidence of protective immunity against rubella despite negative RV IgG.
Journal of clinical virology the official publication of the Pan American Society for Clinical Virology