MECHANISMS OF TOTAL LYMPHOID IRRADIATION-INDUCED IMMUNOSUPPRESSION .2. FAILURE OF CON A-STIMULATED SPLENOCYTES FROM TLI-TREATED MICE TO EXPRESS IL-2 AND IL-2 RECEPTOR RNA

Total lymphoid irradiation is a radiotherapy procedure used as an alternative immunosuppressive regimen in organ transplantation. Following TLI mature lymphocytes are depleted, and splenocytes do not proliferate to mitogens, produce IL-2, or express IL-2 receptors. We now show that mitogen stimulated splenocytes from TLI-treated mice do not secrete IL-2 protein by an IL-2 ELISA assay. Northern blot analysis and RNase protection assays reveal that TLI splenocytes do not make IL-2 RNA or IL-2 receptor RNA following mitogen stimulation. TLI splenocytes produce at least 1000 times less IL-2 RNA after Con A stimulation than normal splenocytes. TLI therapy resembles anti-CD4 therapy and CsA in that each results in an IL-2-“depleted” state. © 1990 by Williams & Wilkins.