Cytokines of the human reproductive tract.

Problem: How is it possible that the female genital tract immunologically does not reject spermatooa not the preimplantation and nidating embryo?
Methods: Four fluids of the human reproductive tract, i.e., human oviductal fluid (hOF), follicular fluid (FF), amniotic fluid (AF), and seminal plasma (SP) were investigated by specific ELISA for 18 cytokines. The concentrations, presence or absence of these compounds were evaluated for their possible role in the immunology of the reproductive process.
Results: Stem cell factor and IL-11 were detected in all reproductive tract fluids examined whereas large amounts of IL-1 beta and IL-1RA was found in AF and hOF. Follicular fluid revealed IL-2. HOF contained IL 2, IL-6, IL-8, TNF-alpha, MIP-1 alpha, IFN-gamma, and high levels of IL-1 beta, IL-10, IL-1RA, and sIL-2R. Amniotic fluid contained sIL-2R, IL-8, IL-1 beta, IL-1RA, IL-6, TNF-alpha, and MIP-1 alpha. No IL-12 or IL-13 was detected in hOF follicular fluid or amniotic fluid. Almost no free TGF-beta 1 or TGF-beta 2 was found in any reproductive tract fluid except seminal plasma. Seminal plasma contained large quantities of free TGF-beta 1 (9,220 +/- 3,635 pg/mL) in addition to large quantities of latent TGF-beta 2 (2,933 +/- 2,169 pg/mL) and TGF-beta 1 (71,000 +/- 3,240 pg/mL). Furthermore, considerable concentrations of IL-8 (1900 +/- 374 pg/mL) and sIL-2R (350 mu/mL) exist in seminal plasma.
Conclusions: HOF contains a high level of IL-10 (588 +/- 304 pg/mL), a powerful immune suppressor which probably plays a role in regulating immune responses in the fallopian tube and possibly in the endometrial cavity. Our observations suggest that seminal plasma with its huge content of TGF beta provides immune protection for sperm. Unfortunately, such high concentrations of TGF beta may also inhibit an immune defense in any organ in which semen is deposited.