Cutting edge:: Protein kinase Cβ expression is critical for export of IL-2 from T cells

Protein kinase C (PKC) plays an integral part in T cell activation and IL-2 secretion. We investigated the role of a particular PKC isoform, PKC beta, in IL-2 production and secretion. The T cell lymphoma line HuT 78 secretes IL-2 in response to the phorbol ester PMA. A PKC beta -deficlent clone of HuT 78, K-4, did not secrete IL-2 in response to PMA stimulation. As assessed by RT-PCR, K-4 expressed mRNA for IL-2 following PMA activation, and intracellular IL-2 protein was detected by immunofluorescence. An enhanced green fluorescent protein-linked PKC beta construct was microinjected into K-4 cells, which,were then stimulated with PMA; those cells that expressed PKC beta could secrete IL-2, as determined by an in situ immunofluorescent assay. This study demonstrates that PKC beta is not necessary for transcription of the IL-2 gene or translation of mRNA to protein, but that expression of this PKC isoform is critical to the export of IL-2 molecules from T cells.