Oral Immunoglobulin Levels are Not a Good Surrogate for Cervical Immunoglobulin Levels

Background: We sought to determine whether oral secretions could be used as a surrogate for cervical secretions for monitoring cervical immunoglobulin (Ig) levels. To do so, we examined (1) whether oral IgG and IgA levels correlated with those observed at the cervix, and (2) whether time of menstrual cycle and other factors previously reported to influence cervical Ig levels were associated with oral IgG and IgA levels. Methods: We obtained oral samples from a group of 85 Costa Rican woman 25–35 years of age measured at three time points during one menstrual cycle. Total IgG and IgA levels were measured by ELISA. Generalized estimating equations methods that account for repeated measures were used to evaluate the association between oral and cervical Ig levels and to evaluate the association between various covariates and oral IgA and IgG levels. Results: We did not observe an association between oral and cervical IgG [linear regression coefficient (LRC) 0.01; 95% CI, −0.05 to 0.07] and IgA levels (LRC 0.02; 95% CI, −0.04 to 0.08). Oral IgG and IgA levels were not influenced by phase of menstrual cycle, in contrast to what has previously been observed for cervical Ig levels. Conclusion: Our data suggest that oral IgG and IgA measures are not a good surrogate for cervical IgG and IgA levels. Future studies should examine whether antigen-specific antibody responses induced by vaccination correlate across mucosal sites.