Membrane and intracellular processing of the LFA-1 macromolecular complex, known to be involved in cytolytic function of T lymphocytes, was investigated in a child with recurrent bacterial infections, impaired natural killer activity, T cell-mediated lymphocytolysis and absent adhesion and migration of phagocytic cells. Monoclonal antibodies to the LFA-1 alpha and beta subunits, able to precipitate the LFA-1 alpha, 180-kDa chain, the p151 chain and beta 94-kDa chain (shared by both alpha chains), were used in immunoprecipitation studies of patient and control phytohemagglutinin-blasts. Neither of the alpha chains nor the beta chain were found in precipitates obtained from 125I-surface-labeled patient cells in contrast to controls. However, the precursor of the LFA-1 alpha chain, a 170-kDa polypeptide, was identified in lysates of biosynthetically labeled patients' cells. These results suggest that the defective membrane expression of the LFA-1 complex may be secondary to the absence of the mature beta chain.