EFFECT OF CYTOKINES AND ANTIADHESION MOLECULE ANTIBODIES ON THE ADHESION OF LYMPHOCYTIC CELLS TO HUMAN SYNCYTIOTROPHOBLAST

We have previously shown that lymphocytic cells bind to cultured syncy tiotrophoblast and that this may be important in the lymphocyte-mediat ed infection of trophoblast with the human immunodeficiency virus (HIV ). Leukocyte-trophoblast adhesion may also have implications for norma l trophoblast function. The following experiments were designed to cha racterize the adhesion systems that mediate the attachment of lymphocy tic cells to trophoblast. Adhesion was assayed by labelling lymphocyti c MOLT-4 clone 8 cells with the fluorescent marker, calcein-AM, and th en incubating them with primary cultures of human syncytiotrophoblast. Adhesion was stimulated by pretreatment of the trophoblast cultures w ith several cytokines either alone or together. These included tumor n ecrosis factor-alpha (TNF-alpha), granulocyte/macrophage-colony stimul ating factor (GM-CSF), interleukin-1 beta (IL-1 beta) and interferon-g amma (IFN-gamma). Stimulation was time- and dose-dependent. In contras t, preincubation of trophoblast cultures with anti-TNF-alpha antibodie s for 2 days reduced MOLT adhesion by almost 50%. Preincubation with o ther anti-cytokine antibodies had no significant effect on adhesion. I n other experiments, adhesion was measured in the presence of antibodi es to known adhesion molecules. Adhesion was reduced by 50% in the pre sence of antibodies to or, integrin or beta(1) integrin. When present together, these antibodies reduced adhesion by almost 85%. Incubation in the presence of antibodies to the very late activation antigen-4 (V LA-4; alpha(4) beta(1) integrin) counter-receptors, VCAM-1 and CS-1, w as without effect. Adhesion was also unaffected by antibodies to LFA-1 , ICAM-1, ICAM-2 LFA-2, or LFA-3. These results suggest that adhesion is mediated by an adhesion system consisting of lymphocyte VLA-4 (alph a(4) beta(1)) and an as yet unidentified counter receptor on trophobla st.