Cell Adhesion Molecules CD11a and CD18 in Blood Monocytes in Old Age and the Consequences for Immunological Dysfunction

Adhesion molecules, such as leukocyte-function-associated antigen (LFA-1 or CD11a/CD18), intercellular adhesion molecule 1 (ICAM-1 or CD54) and Hermes antigen (HCAM or CD44), have important roles in many adhesive interactions involving cells of the immune system. Since it has been shown that many immunological alterations were present in aged subjects, we studied the expression and density of these molecules on peripheral blood lymphocytes and monocytes from healthy old subjects. A decrease in monocyte subpopulations bearing CD11a/CD18 and an increase in CD11a/CD18 and and CD44 antigen density on lymphocytes and on monocytes, respectively, were observed. These changes might be an event in the mechanism leading to the decreased lymphocyte proliferative response in vitro and to other immunological dysfunctions reported in old subjects.