SELECTIVE INDUCTION OF CD11A,B,C CD18 AND CD54 EXPRESSION AT THE CELL-SURFACE OF HUMAN-LEUKOCYTES BY MURAMYL PEPTIDES/

Muramyl dipeptide (MDP), murametide, and murabutide which belong to th e family of the immunoadjuvant muramyl dipeptides were applied directl y to fresh human whole blood and the expression of some surface marker s involved in cell adherence in distinct leukocyte populations was inv estigated, CD11a,b,c/CD18, CD54, and CD49d were selected for their inv olvement in cell adherence, and transferrin receptor (CD71) and low-af finity IgE receptor (CD23) were selected as markers for activated cell s. Whereas CD11a was increased only on monocytes, CD11b, CD11c, and CD 18 were strongly enhanced on monocytes and polymorphonuclear cells (PM Ns) after treatment with MDPs. This increase in membrane expression of integrins, such as CD11b, was not associated with mRNA synthesis, sug gesting a mobilization of the CD11b,c/CD18 intracellular pools present in these cells. In contrast, treatment with MDP, murametide, or murab utide enhanced ICAM-1 (CD54) expression on monocyte and PMN cell surfa ce in association with ICAM-1 mRNA synthesis. No variation of CD49d ex pression was detected on leukocyte surface after incubation with MDPs, Transferrin receptor (CD71) expression and low-affinity receptor for IgE (CD23) expression were increased on monocyte only after incubation with LPS used as positive control. Moreover, no observable change in the selected markers was detected on lymphocyte after MDPs or LPS trea tment. These results indicate that MDPs seem to act preferentially on monocytes and PMNs in increasing the level of molecules involved in ce llular adhesion process, either in provoking the expression of preform ed molecules or in inducing their synthesis. This contributes to under standing the mechanism of the activities of muramyl peptides on specif ic and nonspecific immunity. (C) 1996 Academic Press, Inc.