Connexin 43 Production by Ex Vivo Incubated NK Cells in the Presence of Relevant Cytokine Combinations.

Mouse spleen natural killer (NK) cells were incubated ex vivo in the presence of interleukins (IL)-15 and -18 with or without IL-12 in order to study NK cell proliferation, cluster formation, and expression of gap junction protein connexin 43 (Cx43). While all applied cytokine combinations stimulated all of these functions in treated cells in comparison with control cells incubated without cytokines, IL-12 was found to increase cluster formation and decrease proliferation. Western blotting studies revealed upregulation of Cx43 expression in NK cells treated with IL-12. These results suggest that Cx43 is a marker of cluster formation of NK cells, forming contacts between them after activation of its expression by IL-12. The observed inhibition of proliferation might also be mediated by Cx43, though another possibility is that it could be an independent effect of IL-12 on NK cells.