Bi-directional calcium signaling between adjacent leukocytes and trophoblast-like cells.

Problem: Trophoblasts are believed to play an important role in mitigating immunological responses against the fetus. To better understand the nature of trophoblast-leukocyte interactions, we have studied signal transduction during intercellular interactions.

Method Of Study: Using a highly sensitive microfluorometric ratioing method and Ca²(+) -sensitive dyes, we measured Ca²(+) signals in trophoblast-like cell lines (JEG-3 and JAR) or in leukocytes (neutrophils and monocytes) during intercellular contact.

Results: Trophoblast cell lines exhibit Ca²(+) signals during leukocyte contact. In contrast, leukocytes cannot elicit Ca²(+) signals in non-opsonized tumour cells, suggesting that Ca²(+) signaling is not a general feature of cell-cell encounters. Similarly, leukocytes demonstrate Ca²(+) signals during contact with trophoblast cell lines. Ca²(+) signals were confirmed using three dyes and with the Ca²(+) buffer BAPTA.

Conclusion: We suggest that leukocyte-to-trophoblast interactions lead to mutual Ca²(+) signaling events in both cell types, which may contribute to immunoregulation at the materno-fetal interface.