EXPRESSION OF HUMAN IL-2-RECEPTOR ALPHA-CHAIN AND BETA-CHAIN USING THE BACULOVIRUS EXPRESSION SYSTEM

The genes encoding the alpha- and beta-chains of the human interleukin -2 receptor were expressed in lepidopteran insect cells using the bacu lovirus expression vector system. The corresponding genes were inserte d under the polyhedrin promoter of the Autographa california nuclear p olyhedrosis virus and expressed in the Spodoptera frugiperda insect ce ll line during viral infection. The recombinant receptor proteins were identified in the insect cell lysates by using protein dot blot and E LISA techniques. At 36 h post infection the corresponding proteins wer e clearly detected using anti-IL-2 alpha- and beta-receptor-specific a ntibodies. A large amount of the alpha-chain was also found in the sup ernatant culture media at 72 h post infection and metabolic labelling with [S-35]-methionine indicated that it was proteolytically cleaved i nto a 32 kDa soluble form. A similar soluble or secreted form of the b eta-chain was, however, not observed. Both receptor proteins were expr essed on the surface of the insect cells as determined by flow cytomet ry analysis. Studies performed with the different IL-2 receptor forms (alpha- and beta-chains alone or in combination) in the presence or ab sence of rIL-2 suggest that the receptor proteins when expressed in in fected insect cells are non-functional with respect to tyrosine phosph orylation.