Adhesion to human neurons and astrocytes of monocytes: the role of interaction of CR3 and ICAM-1 and modulation by cytokines.

Monocytes but not unstimulated lymphocytes adhered to human neurons and astrocytes in primary culture, as demonstrated by double labeling. The expression of VCAM-1 was higher on neurons than on astrocytes, whereas that of beta 1, alpha 1, alpha 2, alpha 4 and alpha 5 chains from the integrins and of ICAM-1 was identical on both types of cells. The expression on neurons of ICAM-1, but not of integrins, was up-regulated by exogenous tumor necrosis factor (TNF) alpha, interleukin (IL)-1 alpha and interferon (IFN)-gamma. The same was observed on astrocytes associated with a sharp increase in the expression of VCAM-1. Adhesion between monocytes and neurons or astrocytes was 80% inhibited by mAbs directed against the CR3 determinant on monocytes or against ICAM-1 on neural cells but not by any of the other mAbs against adhesion proteins that were tested. Finally, the level of endogenous production of IL-1 alpha and TNF alpha was greatly increased after the adhesion of monocytes to CNS cells.