Antichlamydial activity of cervical secretion in different phases of the menstrual cycle and influence of hormonal contraceptives.
Cervical secretion from three groups of asymptomatic women, either being oral contraceptive (OC) non-users or users (ethinylestradiol plus desogestrel or levonorgestrel), was tested for its capacity to prevent Chlamydia trachomatis, serotype I, from forming inclusions in cycloheximide-treated McCoy cells. The non-user groups were comprised of 12 women from whom cervical secretion was collected twice weekly during the menstrual cycle and 15 women from whom cervical secretion was collected once or twice weekly. The OC users included 66 women from whom cervical secretion was collected once or twice during their menstrual cycle. Cervical secretion from the non-users produced a decrease in the chlamydial inclusion count by 70%-90% during the first 3 weeks of the menstrual cycle, as compared with the fourth and fifth week when the reduction was 56%-68% (p < 0.001). Secretion from the OC users showed a more effective decrease in the inclusion count during the first 3 weeks of the menstrual cycle, as compared with samples obtained at the fourth and fifth weeks, i.e. 15%-35% vs. 20%-25% (p < 0.001). Cervical secretion of the non-users as compared to the users produced a significant decrease in the inclusion count, viz. 70%-90% vs. 15%-35% (p < 0.001) during the first 3 weeks as compared with 56%-68% vs. 20%-25% (p < 0.001) in the fourth or fifth week. The study suggests that natural resistance to genital chlamydial infection can differ during the menstrual cycle and it may be influenced by oral contraceptive use.