Comparison of normalization methods for measuring immune markers in cervical secretion specimens

Ophthalmic sponges are used to collect undiluted cervical secretions for assessment of markers of genital tract immunity. Heterogeneity in absorbed and extracted sample volumes requires normalization in order to make valid inter-individual comparisons. We evaluated the performance of adjustment by weight and total protein on normalizing inter-individual variability of immune marker measurement due to differences in volume collection. Normalization to total protein resulted in a minimal loss of usable specimens and a significant reduction in the correlation of immune marker concentration to specimen weight compared to weight adjustment. Total protein normalization appeared to be more effective than weight adjustment in reducing the dependence of cervical immune marker concentrations on differences in specimen volume.