Corticosteroid Therapy in Felty''s Syndrome and its Effect on Hypersplenic Rats

S ummary . A patient with Felty's syndrome was treated with prednisone with resulting improvement in anaemia. This was due to a decrease in an expanded plasma volume; it occurred rapidly and was not associated with any apparent change in the size of the spleen.
A contrasting form of hypersplenism was induced in rats, splenic enlargement being due to storage of methylcellulose in the organ. Corticosteroid treatment of these animals produced haematological changes similar to those in the patient although they occurred much more abruptly. The nature of the changes brought about by steroid therapy was investigated by isotope studies.
It is concluded that corticosteroid therapy can improve the anaemia of hypersplenism by reducing an expanded plasma volume and that this effect may occur without parallel improvement in the other haematological changes of hypersplenism. The decrease in plasma volume does not appear to result from a steroid-induced lymphoid involution and a reduction in splenic size. Instead, it seems likely that this treatment affects an intermediary mechanism by which plasma volume is increased in hypersplenic states. The possible nature of this is discussed.