LYMPHOCYTE-MEDIATED CYTOTOXICITY
II. Effect of Prednisolone on Cytotoxicity of Lymphocytes from Normal Persons
1979 Volume 70 Issue 7 Pages 756-764
Details
1979 Volume 70 Issue 7 Pages 756-764
Cytotoxicity of lymphocytes from normal persons against 3 established cell lines was determined by the 14C-leucine incorporation method. The cytotoxicity expressed by MRT (Mean Reduction per Titer) was 37.9±3.7% against HeLa cells, 21.3±4.8% against T24 cells and 10.6±4.8% against MGH-Ul cells. The percent target cell reduction was correlated well with the number of the effector cells, when T24 cells were used as the target cells.
Prednisolone was demonstrated to inhibit the cytotoxicity of lymphocytes from normal persons against T24 cells and HeLa cells. Prednisolone at a concentration of 10-4M remarkably inhibited the cytotoxicity against T24 cells in 91.7±6.2% and yet at a concentration as low as 10-7M produced a significant inhibition of the cytotoxicity in 39.7±11.9%, as compared with the prednisolone-untreated control. The result indicated that the inhibitory effect was closely dose-dependent. A lower concentration (10-7M) of prednisolone exerted a significant inhibition of the cytotoxicity against HeLa cells as well as T24 cells, but the dose-dependant effect of prednisolone was not so clearly demonstrated in HeLa cells as in T24 cells.
The effect of adding 10-5M of prednisolone during the 72hr cytotoxicity test using T24 cells as the target cells was as follows. Prednisolone added immediately after the cytotoxicity test (0h) almost completely abolished the subsequent development of cytotoxicity (94.6%). Prednisolone added after 12 and 24hr of the culture also exerted the inhibitory effect (93.2 and 83.7%, respectively). Considerable inhibitions occurred on adding prednisolone after 36 and 48hr (48.0 and 46.6%), while prednisolone added after 60hr was without significant effect on the cytotoxicity.
The present data indicated that the immune responses of lymphocytes from normal persons may be inhibited by the immunosuppressive effect of prednisolone. Such an inhibitory effect of prednisolone suggests the presence of an antigen recognition phase in the cytotoxic reaction of normal persons. Moreover it may be ruled out that the suppresive effect of Prednisolone occurred predominantly on an early step of immune response, since the inhibitory effect decreased progressively 36hr after the initiation of the cytotoxic reaction and no significant effect was seen during the last 24hr.
