Analysis of cytokine immune response profile in response to inflammatory stimuli in mice with genetic defects in fetal and adult hemoglobin chain expression.

Injections of a crude fetal sheep liver extract (FSLE) containing fetal hemoglobin, MPLA, and glutathione (GSSH) reversed cytokine changes in aged mice. To investigate the role of fetal hemoglobin we derived mice with homzygous deletions for either of the two major ßchains, HgbßmaKO or HgbßmiKO. Hgbßmi is the most prominent fetal Hgbß chain, with Hgbßma more prominent in adult mice. Mice lacking another fetal Hgb chain, HgbεKO, died in utero. CHO cells transfected with cloned Hgb chains were used to produce proteins for preparation of rabbit heteroantibodes. Splenocytes from HgbßmaKO mice stimulated in vitro with Conconavalin A showed a higher IL-2:IL-4 ratio than cells from HgbßmiKO mice. Following immunization in vivo with ovalbumin in alum, HgbßmaKO mice produced less IgE than HgbßmiKO mice, suggesting that in the absence of HgbßmiKO mice had a predeliction to heightened allergic-type responses. Using CHO cells transfected with cloned Hgb chains, we found that only the fetal Hgb chain, Hgbε, was secreted at high levels. Secretion of Hgbßma or Hgbßmi chains was seen only after genetic mutation to introduce the two N-linked glycosylation sites present in Hgbε, but absent in the Hgbß chains. We speculated that a previously unanticipated biological function of a naturally secreted fetal Hgb chain may be partly responsible for the effects reported following injection of animals with fetal, not adult, Hgb. Mice receiving injections of rabbit anti-Hgbε but not either anti-Hgbßma or anti-Hgbßmi from day 14 gestation also showed a bias towards the higher IL-2:IL-4 ratios seen in HgbßmiKO mice.