T-lymphocyte subpopulation in untreated SLE. Variations with disease activity.

An active subpopulation of T lymphocytes characterized by their ability to form early rosettes with sheep erythrocytes (active E-RBL) was studied in the blood of 50 patients with untreated systemic lupus erythematosus (SLE) and in 50 normal controls. The findings were related to the absolute number of circulating lymphocytes and total E-receptor-bearing lymphocytes (total E-RBL). Lupus patients with active disease had markedly decreased absolute lymphocyte counts, but the decrease of both the total and the active E-RBL surpassed what would be expected from the lymphopenia. Patients with inactive disease had moderately decreased absolute lymphocyte counts with a marked and disproportionate decrease in total E-RBL and a moderate decrease in active E-RBL, which seemed to reflect only the absolute lymphopenia. Patients with active disease had significantly lower active E-RBL than those with inactive disease. The changes of these and other lymphocyte subpopulations in relation to disease activity in SLE may reflect the influence of factors leading to T-cell depletion and immaturity. Circulating thymic products may be one of those factors.