Is interleukin-3 important in antiphospholipid antibody-mediated pregnancy failure?

OBJECTIVE: To investigate the effect of interleukin-3 (IL-3) on trophoblast proliferation and expression of beta2-glycoprotein I.
DESIGN: In vitro cell culture using primary trophoblasts and the cell lines Jeg-3, Jar, and BeWo.
SETTING: Department of Obstetrics and Gynaecology, University of Auckland. PATIENT(S): Women with normal pregnancies. INTERVENTION(S): Increasing amounts of IL-3 were added to cultures of primary human trophoblasts, cell lines, or cells treated with a proliferation inhibiting antiphospholipid-like antibody. RNA was extracted from primary human trophoblasts or cell lines. MAIN OUTCOME MEASURE(S): We examined basal and IL-3-stimulated cellular proliferation by [3H] thymidine incorporation assay and secretion of beta2-glycoprotein I into culture medium by semiquantitative immunoblot analysis. Reverse transcriptase-polymerase chain reaction analysis was used to demonstrate the presence of IL-3 receptor transcripts. RESULT(S): The IL-3 treatment did not induce proliferation of highly purified primary trophoblast cultures or cell lines but did induce proliferation of contaminating CD45+ cells in trophoblast cultures. The IL-3 did not overcome the antiproliferative effect of an antiphospholipid-like monoclonal antibody on trophoblast. Secretion of beta2-glycoprotein I by trophoblast cultures was time dependent but unaltered by IL-3 treatment. CONCLUSION(S): Our results question the proposed importance of IL-3 in antiphospholipid antibody-mediated fetal death.