A Skin Reaction in Guinea Pig Homograft Donors with a Cell-free Substance from Recipient Lymph Nodes

IN recent years a material called ‘transfer factor’ has been described which is able to effect the passive transfer of certain delayed hypersensitivities from one human being to another 1 . This substance is obtained from sensitive human leucocytes and can be used to sensitize passively human beings to skin homografts as well 2 . It has been suggested that the homograft reaction is a special case of delayed hypersensitivity 3 . Lawrence's experiences would seem to be compatible with this view. Brent et al. 4 have presented an argument in favour of this interpretation by showing that a delayed type of skin reaction can be elicited in a guinea pig skin graft donor by injection of lymph node tissue taken from the immune recipient. We have used this adaptation of the transfer reaction as an assay method in the isolation of the responsible substances. While this work was in progress, Turk 5 reported the partial purification of a substance apparently very similar to ours, using guinea pigs which had been sensitized to picryl chloride. The comparison of Turk's material with ours may serve to clarify the relationship of the homograft reaction to delayed hypersensitivity.