Biological effect of transferrin on mast cell mediator release during the passive cutaneous anaphylaxis reaction: a possible inhibition mechanism involving iron.

A purification procedure for passive cutaneous anaphylaxis inhibitory factor from BALB/c mouse serum has been previously described. In the present work, this inhibitory activity was found to be related to transferrin. No activity was obtained using iron-unsaturated transferrin, whereas iron-saturated transferrin appeared to be potent. The in vivo inhibition of IgE-dependent mediator release from rat mast cells was also obtained using free iron. This effect was observed when iron was injected prior to or simultaneously with mouse IgE in rat skin. Iron and iron-saturated transferrin could play a role in the mechanism of desensitization by modulating the responsiveness of mast cells.