BIOACTIVITY OF RECOMBINANT FELINE INTERLEUKIN-2 ON HUMAN AND FELINE LEUKOCYTES

Interleukin(IL) -2 is a 16 000 Da protein product of T lymphocytes whi ch is the principle cytokine responsible for clonal expansion of T lym phocytes as a response to antigen exposure, Deficiency of functional I L-2 plays a pivotal role in the pathogenesis of human immunodeficiency syndrome and may be important in the pathogenesis of feline immunodef iciency syndrome as well, Additionally, IL-2 may enhance secretion of interleukin-5 from the TH2 subset of CD4+ T cells, promote peripheral and systemic eosinophilia, and contribute to the eosinophilia which ch aracterizes the inflamed airways of human beings and cats with asthma. We recently reported the sequence of feline IL-2 and the synthesis of recombinant feline IL-2. The purpose of the present study was to eval uate the bioactivity of recombinant feline IL-2 on human and feline le ukocytes. We established dose-response relationships between recombina nt feline IL-2 and radiolabeled proliferating human and feline leukocy tes using thymidine incorporation as a marker of bioactivity. We found that recombinant human IL-2 promotes proliferation of both human and feline leukocytes. However, recombinant feline IL-2 promotes prolifera tion of feline cells, but not human cells.