Low expression of the interleukin (IL)‐4 receptor alpha chain and reduced signalling via the IL‐4 receptor complex in human neonatal B cells

Summary Diminished neonatal antibody responses following infection or immunization may stem in part from intrinsic characteristics of neonatal B cells. In this study, we used B‐cell subset sorting combined with gene expression assays to investigate major differences in the expression of host genes in neonatal and adult naïve B cells. We discovered significantly reduced expression of the interleukin (IL)‐4 receptor alpha chain and reduced IL‐4‐induced signalling in neonatal B cells. Neonatal naïve B cells were susceptible to more rapid and more profound levels of apoptosis when cultured in vitro . They also exhibited a limited response to IL‐4 treatment compared with adult cells. The expression level of the IL‐13 receptor alpha 1 chain, a key component of the IL‐13 receptor/IL‐4 type II receptor, and the response to IL‐13 treatment for protection against apoptosis in neonatal B cells were similar to those of the adult B cells. These studies suggest a possible mechanism underlying the limited magnitude and durability of neonatal antibody responses.