Enhancement of a delayed hypersensitivity reaction to a contact allergen, by the systemic administration of interleukin-2.

The immunopharmacological effects of interleukin-2 (IL-2) on the sensitization and effector phases of the delayed-type hypersensitivity (DTH) reaction were studied using contact sensitivity to the haptenizing agent dinitrochlorobenzene (DNCB). When administered at the time of priming to DNCB, IL-2 had no effect on the subsequent magnitude of the response. Interleukin-2 was, however, able to increase the magnitude of the response when given at the time of secondary challenge; the degree of change was directly related to the dose of IL-2. The proportions of T cells in the draining lymph node and spleen of IL-2-treated animals decreased by approximately one-third, but there was no alteration to the balance between CD4+ and CD8+ T cells. The results suggest that the increase in DTH observed was due to a pharmacological effect rather than to an increase in T-cell number.