Alteration of T-lymphocyte subpopulations in sarcoidosis

The present study characterized subpopulations of T lymphocytes from patients with sarcoidosis by the presence of Fc receptors for either IgG or IgM. There was a consistent reduction in the total number of circulating T cells. The percentage of T lymphocytes with receptors for the Fc portion of IgG (T_G) was significantly increased and the percentage of T cells bearing receptors for IgM (T_M) was significantly decreased when compared to control values. There was no change in the proportion of cells which lacked either receptor (T_{NON-G NON-M}). The absolute numbers of each T-lymphocyte subpopulation were diminished but T_G cells were less severely reduced than either T_M or T_{NON-G NON-M}. Thus, there is a disproportionate reduction in distinct subpopulations of T lymphocytes in patients with sarcoidosis which results in a relative increase in T_G lymphocytes and a relative decrease in T_M lymphocytes. Such alterations in lymphocyte subpopulations may explain some of the immunological aberrancies characteristic of sarcoidosis.