THE EFFECT OF STEROIDS ON THE CIRCULATING LYMPHOCYTE POPULATION II. STUDIES OF THE THORACIC DUCT LYMPHOCYTE POPULATION OF THE GUINEA PIG AFTER NEONATAL THYMECTOMY -AND PREDNISOLONE TREATMENT.

L Hedman, P Lundin

Abstract


The effect of corticosteroids on the lymphatic tissue
and circulating lymphocyte pool in the guinea pig
has been studied. No signs of increased lympho·
cytolysis was seen and only after 1-2 weeks u eat·
ment with a long acting corticosteroid was the
thymic cortex reduced and thymic weight decreased.
Three ho urs after inject ing a short acting steroid a
30- 40 per cent reduction in the thoracic duct cell
count was seen in both control and thymectomized
animals. Res titution to pretreatment cell level was
completed in 17 hours. Mono nuclear celJs in the
blood were markedly depressed up to 40 hours.
The changes in the circulating lymphocyte pool in
the resistant guinea pig seem to be in principle the
same as in the sensitive rat but Jess pronounced.
It can be concluded that the lymphocyte level in the
circulating pool is thymus dependent but restoration
of the cell count after steroid treatment is independent
of intact thymic functio n. This data
supports the hypothesis of lymphocyte trapping and
redistr ibution after a single steroid ueatment.
Key-words: Lymphocyte - Thoracic duct -
Lymphoid tissue - Blood - Corticosteroid -
Thymectomy - Guinea pig


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