Regulation of CD31 expression and interleukin-4 production by human cord blood CD4⁺ t cells with interleukin-4 and interleukin-7

Background: T helper 2 cell type cytokines, such as interleukin (IL)-4 and IL-5, play pivotal roles in the development of allergic diseases. However, the mechanism by which naive CD4⁺ T cells acquire the ability to produce these cytokines remains unclear. Recently, it was reported that IL-7 induces the ability to produce IL-4 as well as interferon (IFN)-γ and IL-5 in naive CD4⁺ T cells without TCR stimulation. To further analyze the mechanism of acquiring IL-4-producing ability by naive CD4⁺ T cells, the effects of IL-7 on human cord blood CD4⁺ T cells were compared with those of IL-4, which induced the ability to produce IFN-γ but not IL-4. Results: Interleukin-7 preserved the population of CD4⁺ CD31- T cells in cord blood and induced their IL-4 producing ability without T cell receptor (TCR) stimulation, while IL-4 induced CD31 on CD31- T dells and could not induce their IL-4-producing ability. Both the CD31-inducing effect and the inhibitory ; priming effect for IL-4-production by IL-4 were also observed after cord blood CD4⁺ T cells had been primed with IL-7 and acquired the IL- 4-producing ability. Conclusions: Interleukin-7 induced the IL-4-producing ability in naive CD4⁺CD31^- T cells without TCR stimulation, suggesting that the signal transduction via CD31 may have an inhibitory effect on the acquisition of the IL-4-producing ability by cord blood CD4⁺ T cells in the absence of TCR stimulation.