Several adhesion molecules and CD45RO have been reported to be upregulated on the cell surface of 'memory' T cells. Using triple-color flow cytometry, we compared the levels of typical 'memory' cell markers on peripheral blood T-cell subpopulations in a number of kidney transplant recipients, patients with systemic lupus erythematosus, newborn infants and healthy donors. CD45RO, VLA-beta 1 (CD29), VLA-5 alpha (CD49e), LFA-1 (CD11a/18), and CD2 were found to be closely coregulated on CD4+ T cells, while regulation of VLA-2 alpha (Cd49b), VLA-4 alpha (CD49d) and CD44 was quite discordant. In CD8+ T cells, by contrast, multiple subsets of 'memory'-type cells were distinguished. Unlike TCR alpha/beta T cells, which expressed either high or low levels of LFA-1, TCR gamma/delta cells all expressed high levels of LFA-1 (CD11a/CD18). Examination of T cells from kidney graft fine-needle aspiration biopsies during rejection revealed intragraft accumulation of 'memory'-type T cells expressing high levels of CD2 and LFA-1 (CD11a/CD18). Regarding peripheral blood T-cell subsets, differences between patients and healthy controls were only of a quantitative nature.