MECHANISMS OF CORTICOSTEROID ACTION ON LYMPHOCYTE SUB-POPULATIONS .4. EFFECTS OF INVITRO HYDROCORTISONE ON NATURALLY OCCURRING AND MITOGEN-INDUCED SUPPRESSOR CELLS IN MAN

The effects of in vitro hydrocortisone (OHC) on human peripheral blood (PB) suppressor cell function were investigated. Two types of suppressor cells were studied: (i) the naturally occurring PB suppressor cell seen in 10% of normal people whose lymphocytes do not respond to in vitro PWM stimulation with direct anti-SRBC PFC responses, and (ii) Con A-generated suppressor cells. The addition of OHC to PWM-stimulated cultures from nonresponders reconstituted the PFC response in two of three individuals. The addition of OHC to allogenic cocultures of nonresponder and responder lymphocytes completely inhibited the ability of the naturally occurring suppressor cell of the nonresponder cultures to inhibit the PFC responses of normal responders. Preincubating the nonresponder cultures in 10-5 M OHC for 30 min followed by washing did not inhibit suppressor function, whereas readdition of OHC to cocultures did inhibit nonresponder suppressor cell function. The addition of up to 10-4 M OHC to previously generated Con A-activated suppressor cell-fresh cell cocultures in vitro did not prevent or inhibit mitogen-activated suppressor cell function. However, preincubation of PB cells for 6 hr prior to the addition of Con A prevented the generation of suppressor cells and in two of eight experiments generated a population of cells which were in and of themselves mitogenic for autologous fresh PB. Thus, the function of naturally occurring suppressor cells as well as the induction but not the function of Con A-activated suppressor cells is sensitive to pharmacologic levels of OHC. The effect of OHC on naturally occurring suppressor cell function or on the generation of suppressor cells by Con A did not involve cell lysis, but rather was a reversible phenomenon requiring the continued presence of OHC in culture. © 1979.