Host immune response in chlamydial cervicitis

In order to study host immune responses to Chlamydia trachomatis infection in patients with chlamydial cervicitis, lymphoproliferative responses to purified protein derivative (PPD) and Chlamydia trachomatis antigen (elementary bodies) were studied in 15 patients and 10 normal control subjects. A significant lymphoproliferation of peripheral blood mononuclear cells (PBMC) was obtained with PPD and C. trachomatis antigen (P < 0.001) as compared to unstimulated PBMC showing that antigen-reactive T-cells are present in patients. There was no significant difference in the lymphoproliferation response to C. trachomatis in patients as compared to control subjects suggesting that the cell-mediated immune (CMI) response in peripheral blood is not altered in chlamydial cervicitis. Inhibition of IL-2 production in cervical secretions ranged from 44 to 84% in patients with chlamydial cervicitis while supernatants derived from PBMC stimulated with PPD failed to show inhibition. However, there was no inhibition of IL-2 production in secretion or supernatants stimulated with PPD in control subjects, thereby showing that local cell-mediated immunity is impaired in patients. Significant C. trachomatis specific IgA antibodies, in cervical secretions, were present in only three of 15 patients. C. trachomatis specific IgG, IgM and IgA were detected in the serum of most patients, suggesting that serum antibodies do not confer immunity at the local site. We conclude that although circulating antigen-reactive T-cells are present in chlamydial cervicitis patients, absence of protective antibody as well as impairment of local cell-mediated immunity may be responsible for alteration of the mucosal defence mechanism against chlamydial infection.