The interleukin 2 secretion defect in vitro in systemic lupus erythematosus is reversible in rested cultured T cells.

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Abstract
Interleukin 2 (IL 2) secretion in response to mitogenic stimulation in vitro is strongly reduced in circulating T lymphocytes from patients with SLE. It is still not clear how this abnormality relates to the B cell hyperactivity in the disease. Some investigators proposed that an intrinsic T helper cell defect could lead to suppressor cell dysfunction and autoimmunity. Others have found that in fact increased suppressor cell activity can cause IL 2 hyposecretion. In the present study we report that the IL 2 secretion in response to PHA plus PMA by T cells from patients with SLE, which initially was decreased by a factor of 10 as compared with the IL 2 secretion in blood donor T cells, was restored when the T cells were rested for 2 to 3 days in culture before stimulation. IL 2 hyposecretion in SLE T cells and the kinetics of normalization in culture were not changed by the addition of normal adherent cells during the stimulation with PHA/PMA, occurred in the absence of significant cell death or proliferation or change of the T4:T8 cell ratio during the resting culture, were not due to a maturation of immature T6-positive cells (less than 1.5% T6 cells in SLE T cells), and also occurred in T8-depleted T4 cells alone. Furthermore, a normalization of IL 2 secretion took place in the presence of either SLE serum or normal serum, and the addition of fresh autologous T cells to 3-day-cultured SLE T cells did not cause suppression of IL 2 secretion. These data show that some rapidly reversible defect occurs in circulating T helper cells in SLE. That this could reflect an exhaustion of T helper cells that have been activated in vivo is discussed.