Intramuscular 17α-hydroxyprogesterone caproate administration attenuates immunoresponsiveness of maternal peripheral blood mononuclear cells

OBJECTIVE: 17 alpha-hydroxyprogesterone caproate (17P) may decrease risk of prematurity by suppressing maternal immunity. We hypothesized that in vivo 17P treatment attenuates immunoresponsiveness of peripheral blood mononuclear cells (PBMCs). STUDY DESIGN: Study subjects were gravidas receiving weekly prophylactic intramuscular 17P injections. Peripheral blood samples were obtained at 21-27 weeks' gestation. Gestational age-matched, drug-naive gravidas served as controls. To simulate infection, isolated PBMCs were stimulated with lipoteichoic acid (LTA) or lipopolysaccharide (LPS). Extracellular interleukin-6 (IL-6) concentrations were quantified by an enzyme-linked immunosorbent assay. RESULTS: Unstimulated IL-6 levels were comparable in PBMCs derived from drug-naive and 17P-treated subjects. LPS and LTA induced a dose-dependent elevation of IL-6 in control PBMCs. In patients who received exogenous 17P, LPS, and LTA stimulated induction of IL-6 was significantly decreased compared with controls (P = .005 and P = .02). CONCLUSION: In vivo 17P attenuated immunoreactivity of PBMCs in our in vitro model of Gram-positive and Gram-negative bacterial infection.