THE EFFECT OF STEROIDS ON THE CIRCULATING LYMPHOCYTE POPULATION I. CHANGES IN THE THORACIC DUCT LYMPHOCYTE POPULATION OF THE RAT AFTER NEONATAL THYMECTOMY AND PREDNISOLONE TREATMENT.

L Hedman, P Lundin

Abstract


The influence of prednisolone on the thoracic duct
cells of rats was measured by the cell count in
lymph at different times after a single injection and
correlated with lymphocytolysis in lymphoid tissues.
In both control and neonatally thymectomized
animals there was a marked fall in the cell count
and flow at 3 hours and the percentage reduction
was greater in thymectomized animals. Restitution
was rapid in both groups and pretreatment levels
were regained in 17 hours. The blood mononuclear
cells followed the same pattern. In animals with an
intact thymus adrenalectomy causes a significant
increase in thoracic duct cell counts but in neonat·
ally thymectomized animals thoracic duct lymph is
unchanged after adrenalectomy. It ean be concluded
that in the rat lymphocyte level in the circulating
pool is thymus dependent but restoration of the
circulating cell count after steroid induced invo lut·
ion is independent of intact thymic function.

Our data support the hypothesis of lymphocyte
trapping and redistribution as a major mechanism
after a single cortisone dose.


Key-words: Lymphocyte - Thoracic duct -
Lymphoid tissue - Blood - Corticosteroid -
Thymectomy - Adrenalectomy - Rat


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