Immunostaining for glycoproteins of the LFA-1 family (leucocyte function-associated antigens) was demonstrated on cells in the corona around senile plaques in Alzheimer's disease (AD) and in small glial cells in the subcortex of patients with AD and controls. These cells, which are usually referred to as microglial cells, showed positive immunohistochemical staining with monoclonal antibodies directed against the α-chains of all 3 LFA-1 family members, i.e. LFA-1, iC3b-receptor and P150,95, as well as with a monoclonal antibody against the common β-chain. In the corona a diffuse staining for a ligand of LFA-1, intercellular adhesion molecule (ICAM)-1, was found as well. It is suggested that these molecules of the LFA-1 family may have a function in the dynamics of neuritic degeneration and sprouting.