Tubal factor infertility is associated with antibodies against Chlamydia trachomatis heat shock protein 60 (HSP60) but not human HSP60.

BACKGROUND Serum antibodies against major outer membrane protein (MOMP) and heat shock protein 60 (HSP60) from Chlamydia trachomatis are correlated with sequelae following infection. Since bacterial and human HSP60 share considerable sequence homology, cross-reactivity to human HSP60 is suggested as being involved in tubal factor infertility (TFI). The aim was to investigate whether antibodies to human HSP60 are associated with TFI, and to evaluate antibody testing in TFI diagnosis. METHODS Serum levels of antibodies against chlamydial MOMP and HSP60 from C. trachomatis, Salmonella enterica Enteritidis, Campylobacter jejuni and human HSP60 were analysed by enzyme-linked immunosorbent assay in three groups of infertile women: women with TFI (n = 70), controls with normal fallopian tubes (control group 1, n = 92) and a subgroup of women with normal fallopian tubes and sero-positive for either chlamydial MOMP or chlamydial HSP60 (control group 2, n = 28). RESULTS Serum levels of immunoglobulin (Ig)G1 and IgG3 antibodies against MOMP and HSP60 from C. trachomatis were elevated in patients with TFI compared with non-TFI individuals (group 1; P < 0.001), while levels of IgG3 against MOMP and IgG1 against HSP60 were higher in the TFI group compared with control group 2 (P = 0.04 and P = 0.03, respectively). Levels of antibodies against human HSP60 did not differ between groups. CONCLUSIONS Our findings confirm an association between TFI and antibodies to MOMP and HSP60 from C. trachomatis, suggesting antibody testing as a supplement in TFI diagnosis. No connection was observed between TFI and antibodies to human HSP60, pointing to an infectious rather than an autoimmune inflammation as the cause of TFI.