Comparison of adult and fetal cytokine secretion during mixed lymphocyte reactions

Umbilical cord blood transplants are associated with a lower incidence of graft-versus-host disease (GVHD) than adult marrow or peripheral blood stem cell transplants, and this could be related to a difference in cytokine production between fetal and adult mononuclear cells after allogeneic stimulation. Mixed lymphocyte reactions (MLRs) involving adult cells were associated with greater interferon-gamma (IFNgamma) secretion than MLRs between cord blood cells, although IL-2 secretion was similar. Experiments in which T cells were separated from accessory cells then recombined in artificial combinations indicated that differences in T cells were primarily responsible for the greater [IFNgamma]:[IL-2] ratios generally found after MLRs involving adult cells compared to fetal cells, but accessory cells also influenced this ratio. The cellular basis for the observed difference was not established, but mononuclear cell preparations from cord blood contained significantly higher proportions of CD16(+)56(-) NK-type cells and a CD19(+)1c(+) B cell subset, as well as more CD45 RA-expressing nai;ve T cells.