Molecular cloning and expression of equine interleukin 2

We have cloned equine IL-2 cDNA in vitro using the polymerase chain reaction (PCR) and primers based on the human IL-2 sequence. The cloned product appears to contain the entire coding region for equine IL-2 based on homology with other known sequences. When expressed in COS cells, the recombinant product augmented the proliferative response of equine peripheral blood mononuclear cells to concanavalin A, however, it failed to support the continued proliferation of murine CTLL-2 cells. Specific substitutions in those regions associated with p55 and p75 binding appear to account for this species-specifity.