PRODUCTION AND CHARACTERIZATION OF MONOCLONAL-ANTIBODIES TO HUMAN INTERLEUKIN-12

Interleukin-12 is a cytokine that plays a central role in mediating ce ll mediated immunity via enhancement of a T(H)1 cell response. IL-12, unusually for a cytokine, has a heterodimeric structure made up of 35 kDa and 40 kDa subunits. The aim of this study was to produce and char acterize monoclonal antibodies to recombinant human IL-12. Twenty-two monoclonal antibodies to IL-12 were successfully produced and subunit specificity determined using recombinant human IL-12 and chimeric muri ne/human IL-12. All antibodies were shown to react with the p40 subuni t by ELISA and immunoblotting with three of the MAbs being found to cr oss-react with murine IL-12. Using two individual bioassays for IL-12, seven of the MAbs were shown to neutralize biological activity of IL- 12. Ten of the antibodies were found to be of use in immunocytochemist ry, reacting with LPS-stimulated peripheral blood monocytes. The appro aches and difficulties encountered in characterizing antibodies to a h eterodimeric cytokine are discussed together with possible reasons for the failure to generate antibodies to the p35 subunit.