Progesterone regulates IL12 expression in pregnancy lymphocytes by inhibiting phospholipase A2.
OBJECTIVE
Progesterone-induced blocking factor (PIBF) is one of the pathways that mediate the immunological effects of progesterone. PIBF inhibits natural killer (NK) cytotoxic activity. Recently we showed that neutralization of PIBF results in an increased interleukin (IL)-12 expression, which is corrected by cyclooxygenase inhibitors. As exogenous arachidonic acid (AA) voids the NK blocking effect of PIBF, it is likely that PIBF acts before the level of the cyclooxygenase enzyme. Therefore in this study we investigated the effect of PIBF neutralizing antibody and simultaneous phospholipase A2 inhibitor quinacrine (Q) treatment on IL-12 production.


METHODS
Pregnancy lymphocytes were treated with anti-PIBF antibody or lipopolysaccharide (LPS) as a positive control, in the presence or absence of Q. IL-12 expression by PBMC was detected by immunocytochemistry.


RESULTS
Neutralization of PIBF as well as LPS treatment resulted in an increased IL-12 expression, which was corrected by simultaneous Q treatment. Pre-treatment of lymphocytes with progesterone prevented the stimulating effect of LPS on IL-12 production.


CONCLUSIONS
Progesterone binding of the lymphocytes is followed by the release of PIBF that inhibits AA release. The subsequent block of prostaglandin synthesis reduces IL-12 production and results in a lowered cytotoxic NK activity, which may contribute to a normal pregnancy outcome.
Department of Medical Microbiology and Immunology, Medical School, Pecs University, Pecs, Hungary.
G
G
Par
J
J
Geli
N
N
Kozma
P
P
Varga
J
J
Szekeres-Bartho
D000906:Antibodies / Q000276:immunology; D016718:Arachidonic Acid / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D018664:Interleukin-12 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D010741:Phospholipases A / Q000037:antagonists & inhibitors*; D054467:Phospholipases A2; D011247:Pregnancy / Q000378:metabolism*; D011257:Pregnancy Proteins / Q000276:immunology; D011374:Progesterone / Q000378:metabolism*; D011796:Quinacrine / Q000494:pharmacology; D013491:Suppressor Factors, Immunologic
D000906:Antibodies; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; C110058:PIBF1 protein, human; D011257:Pregnancy Proteins; D013491:Suppressor Factors, Immunologic; D018664:Interleukin-12; D016718:Arachidonic Acid; D011374:Progesterone; D010741:Phospholipases A; D054467:Phospholipases A2; D011796:Quinacrine