>>Is alpha d found on immature eosinophils or on basophils?
>>What interaction is there between IL-5R and alpha d expression? Presumably IL-5 would induce alpha d by IL-5R-mediated events.
>We did not study the expression of alpha-d on immature cell types; however, it seems reasonable to assume that alpha-d expression is present as these cell types mature, much like CD11b/CD18. Indeed, Van der Vieren, et. al. have shown that the promyelomonocytic cell line HL60 expresses alpha-d and this expression is not affected by DMSO treatment (Immunity. 1995 Dec;3(6):683-90.).
>In our initial studies we did not characterize further the induction of alpha-d expression by IL-5. Most likely this effect is mediated through the IL-5R; however, we cannot rule out a more indirect pathway.
Thanks for the reply. We have found that one of the earliest events in eosinophil/basophil differentiation is the appearance of beta-7 integrin. This occurs during butyrate-induced HL-60 cell eosinophil-basophil lineage commitment, in cord blood CD34 cells differentiating to this pathway (after CD34-hi is lost), and in peripheral blood eo-baso colony cells in methylcellulose cultures (Lundahl et al, submitted). Whether IL-5, a cytokine involved in inducing some of these differentiation events (cord blood and methylcellulose), is a trigger for acquisition of beta-7, was not directly addressed.