Cytokine production by cord blood mononuclear cells stimulated with cows milk proteins in vitro: interleukin‐4 and transforming growth factor β‐secreting cells detected in the CD45RO T cell population in children of atopic mothers

Summary Background Food antigens from the maternal circulation may sensitize fetal T cells in utero and be an important determinant in the development of food allergy. Methods Here we have examined the spontaneous and recall response to cow's milk proteins of cord blood mononuclear cells (CBMC) of newborn children, using single cell ELISPOT assays. Results In term newborns, confirming previous studies, the spontaneous cytokine response of CBMC is dominated by IL-4, IL-5, IL-10, and as shown here for the first time, TGF-β. For TGF-β only, the response of samples from infants of atopic mothers was significantly lower than samples from infants of non-atopic mothers. In vitro stimulation of CBMC with bovine serum albumin, casein and β-lactoglobulin resulted in a significant increase of all cytokine-secreting cells, again dominated by T helper type 2 (Th2) cytokines. There was a clear tendency for samples from infants of atopic mothers to have lower Th2 responses than samples from infants of non-atopic mothers, which was particularly significant for both IL-4 and TGF-β. Spontaneous cytokine secreting cells were virtually absent in cord blood from infants  34 weeks. To explore whether the cytokine secreting cells were in the naive CD4+ CD45RA population or memory CD4+ CD45RO T cells, these subsets were purified by positive and negative selection and tested for spontaneous and cows milk protein-induced cytokine responses. Strikingly, although the responses were small, the CD45RO+ cells from children of atopic mothers showed significant spontaneous and antigen-specific IL-4 and TGF-β responses, whereas the same population from infants of non-atopic mothers showed virtually no response. In addition CD45RA+ cells from infants of mothers with maternal atopy showed decreased IL-4 and TGF-β responses, especially the latter. Conclusions The cows milk antigen-specific IL-4 and TGF-β responses preferentially seen in the memory cell subset of infants with a maternal history of atopy strongly suggests Th2 skewing to dietary antigens in utero.