IMPORTANCE OF ICAM-1 FOR ACCESSORY CELL-FUNCTION OF MONOCYTIC CELLS

We investigated to what extent the adherence molecule ICAM-1 is important for the accessory cell function of cells of the monocyte lineage. A monoclonal antibody to ICAM-1, 7F7, inhibited the accessory cell function of human peripheral blood monocytes cultured in the presence of serum for 1–3 days. Monocyte, cultured for 4–7 days still expressed ICAM-1 but their accessory cell function was no longer inhibited by the antibody 7F7. Dendritiform accessory cells, obtained by culture of peripheral blood monocytes in serum free medium for 1–2 days also expressed ICAM-1 and their capacity to stimulate T-cells was also abrogated by antibody 7F7. These findings suggest that ICAM-1 on the surface of accessory cells of a certain differentiation stage seems to contribute to the capacity of these cells to stimulate T-cells but, that in some situations accessory cell function can occur normally without requiring ICAM-1 dependent cell to cell interactions. © 1990, Gustav Fischer Verlag · Stuttgart · New York. All rights reserved.