It is generally accepted that the homograft reaction is the one of an immune response on the part of the recipient against the graft. The majoriry opinion is that cellular or delayed type immunity is the major effect in graft rejection, although antibodies can also be involved.
Various measures were attempted to supress homograft rejection during half a century. Althouh X-irradiation is one of them, little is known about effect on the fate of skin grafts or on immune response.
As part of a program aimed at prolonging the life of skin grafts, mice were exposed to different doses of X-irradiation. The time permitted to elapse between irradiation and grafting was also varied.
Simultaneously with grafting, the animals were injected with classical antigen, Freund’s complete adjuvant and bovine r-globulin, respectively.
The results was as following:
1. 250r. 400r. and 600r total body irridiation increased homograft rejection time in mice.
Maximum prolongation of skin graft rejection time occurred with 400r, and with 600r, when grafting was done on the same day as irradiation. A 2-fold increase in mean rejection time was observed.
2. No graft advantage appears to be gained by increasing the radiation dose from 400r to 600r, to obtaining prolongation of homograft rejection time, because on increasing of LD? to 50%.
3. The observation that maximal depression of delayed hypersensitivity to PPD (purified protein derivative) occurred when the antigens were presented imediately after irradiation, where as maximal depression of circulating antibodies to BGG occurs when the antigens are given 7days after.
The time between irradiation and antigen appears to be as critical.
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