INFLUENCE OF CORTICOSTEROIDS ON LYMPHOCYTE RECIRCULATION

Abstract

The effect of corticosteroids on cell kinetics and cell

size distribution in the circulating lymphocyte populations

of the steroid sensitive rat and the steroid

resistant guinea pig were studied.

A single high steroid dose (prednisolone) induced a

rapid depression of the lymphocyte level both in

normal and thymectomized animals of both species

and a restitution within one day. The returning cell

population showed the same size distribution and

label index profile as before involution. The main

effect of a single steroid dose seems to be a ,trapping"

of lymphocytes with redistribution from the

circulation to some tissues. The difference between

the two species seems to be quantitative with a more

pronounced trapping mechanism in the sensitive rat

but a certain degree of lymphocytolysis can not be

excluded in this species. The steroid action seems to

be on both T-and B-lymphocytes and the restitution

of cell levels after acute involution is independent of

an intact thymic function. The same course of events

was observed in the normal rat after stress, but not

in the thymectomized rat.