Oxisuran and immune reactions: mediation of oxisuran action by the adrenal glands.

Oxisuran was tested in a TAR system and for the DH on SRBC. Besides immunosuppressive properties in the TAR and DH also mentioned by other authors, stimulation was found after prolonged administration. No effect of oxisuran on the humoral response was observed. The action of oxisuran was suggested to be indirect, effected by stimulation of the PAG system. Adrenalectomy of mice made animals non-liable for oxisuran action measured in the TAR assay. Oxisuran caused an increase of the corticosterone plasma level with a peak after four daily injections. This was paralleled by a peak in adrenal gland weight and a minimum in thymus size. The reduction in these effects after five injections (tachyphylaxis) suggest that a feedback mechanism is involved. Comparison of thymus weights after oxisuran and corticosterone administration indicates that a daily dose of 100 mg oxisuran/kg corresponds with 1.5 mg corticosterone/kg. The effects of oxisuran in the TAR and on the DH and the feedback phenomenon could be imitated with 1.5 mg corticosterone/kg. The mononuclear phagocyte has been proposed as the main target cell of oxisuran action, mediated by the PAG system.