MYCOBACTERIUM-AVIUM REDUCES EXPRESSION OF COSTIMULATORY ADHESION MOLECULES BY HUMAN MONOCYTES/

Organisms of the Mycobacterium avium complex survive the hostile envir onment of their host cells, the macrophages, and evade immune response , in part, by interfering with processing and presentation of antigen. We studied the effect of infection with M. avium on the expression of the costimulatory/adhesion molecules (referred to herein as accessory molecules) because generating an efficient T cell response requires b oth the recognition of processed antigen and the participation of acce ssory molecules. Human peripheral blood monocytes displayed reduced le vels of CD54, CD58, and CD86 molecules 1 day after in vitro infection. The reduction in the expression of accessory molecules was not mediat ed by endogenous IL-10 or prostaglandin because monocytes infected in the presence of either anti-IL-10 neutralizing antibody or indomethaci n diet not express normal levels of surface CD54, CD58, and CD86 molec ules. Consistent with these phenotypic changes, M. avium-infected mono cytes were less effective in supporting Ag-independent proliferation o f autologous CD4(+) T cells. (C) 1997 Academic Press.