DECIDUA AS A SITE OF EXTRATHYMIC V-GAMMA-I T-CELL DIFFERENTIATION

PROBLEM: Decidual tissue is an interface between the host and fetus, w hich is regarded as a natural allograft. We have reported the possible presence of extrathymic T cells in human decidua through the expressi on of recombinase-activating genes in the decidual CD16(-) CD56(bright ) large granular lymphocytes. METHODS: In this study we analyzed expre ssion of TCR V gamma delta gene segments in peripheral lymphocytes and decidual and nonpregnant endometrial samples using RT-PCR and oligonu cleotide hybridization. RESULTS: Interestingly, a limited repertoire o f V gamma gene segments were discovered in decidual lymphocytes of nor mal pregnancy when compared with peripheral lymphocytes, whereas usage of V delta gene segments were ubiquitous in peripheral and decidual l ymphocytes. Strong expression of V gamma I gene segment, often exceedi ng 50% of total V gamma, were noted in all (13/13) pregnant decidual t issues obtained at different gestational stages. Interestingly, this p redominance of V gamma I gene is also noted in nonpregnant endometrial samples and the decidua of patients with ectopic pregnancies. CONCLUS IONS: Our results suggest the nature of decidual V gamma I T cells as possible suppressors of rejective maternal cytotoxic T cells during th e maintenance of normal pregnancies.