Fate of skin allografts in normal mice injected with antigraft strain globulin in relation to the IgG1 and IgG2 class of the antibodies.

A recent study of the effects on skin allografts of alloantibody-containing globulins of the mouse indicated that such globulins can have a variety of effects on the fate of the grafts, ranging from accelerated rejection to prolonged retention. We have also shown evidence of the presence in such globulins of anti-graft strain antibodies of IgG2 class by complement-dependent reactions of such globulin, and of antibodies of IgG1 class by the finding that the titres of these reactions were elevated on treatment of the globulin with anti-mouse IgG1 serum. Further, it was shown that the increasing titre of these antibodies on treatment with increasing amounts of the anti-IgG1 serum reached a plateau level which is the actual titre of an IgG2 anti-graft strain antibody, such as the suppressive antibody, in these preparations. The difference between the plateau level and the original level of suppressive titre was therefore considered to provide a measure of the competing, IgG1-class, antibody. The present study has examined the relation, in anti-graft strain ascitic fluid globulin preparations, between this measure of relative content of anti-graft strain antibody of IgG1 class and the effects of these globulins on the fate of skin allografts. Of globulin preparations which had caused various effects on the skin grafts, portions were treated by adding increasing amounts of anti-mouse IgG1, removing the resulting precipitates, and testing the supernatant fluids for suppressive titre, to determine the plateau level of titre attained. All pools which caused accelerated rejection of BALB/c skin grafts showed increases from original to plateau titres in the lowest range, log 0.1–1.2; all those causing prolonged retention showed such differences in the highest range observed, log 2.1–3.1. Globulins giving partial effects of accelerated rejection, or negative results, showed corresponding intermediate of ranges the increases in titre produced by the anti-IgG1 serum. For a test of this relation, use was made of an earlier observation of a failure to produce accelerated rejection by later-day globulins of mice which had, at 11–13 days, produced rejecting globulins. The failure to cause accelerated rejection by such later-day globulins was confirmed, and these later globulins also showed consistently greater increases of titre from original to plateau level. Similarly, of mice whose 11–13-day globulin pools had caused no significant difference from normal rejection time, later globulins showed, again, greater differences between original and plateau titres than the 11–13-day globulins, and again a difference in effect on skin graft rejection, in this case a significant prolongation of graft retention, in comparison with the negative results given by the 11–13-day pools.