THE ROLE OF COMPLEMENT IN THE PASSIVE CUTANEOUS REACTION OF MICE

Intradermal injection of mice with ribonuclease antibody, followed by intravenous injection with ribonuclease, resulted in permeability increase, demonstrable by "blueing." The size of the blued area depends on the quantity of antibody injected and on the interval between the two injections. If antigen was injected first and antibody was injected subsequently, a similar increase in permeability was observed in animals having a complete complement system (MuB1-positive) and in animals which have a deficient complement system (MuB1-negative). Marked differences in response were observed between these two types of mice if antigen was injected some hours after the antibody. In MuB1-negative mice, a blueing reaction was not observed at intervals between injections (2½ hours if 3 µg N antibody and 15 hours if 25 µg N antibody were injected intradermally) at which MuB1-positive animals showed a marked permeability increase. At these intervals, blueing did occur in MuB1-negative animals if they were injected with the serum of MuB1-positive mice or with fresh guinea pig serum. Blueing was not induced if the serum of MuB1-negative mice or heated guinea pig serum was injected. The occurrence of two distinct phases of the cutaneous reaction, of which only one involves the complete hemolytic complement system, was deduced from these observations

IMMUNOSUPPRESSIVE AND GRAFT-REJECTING ANTIBODIES IN HETEROLOGOUS ANTI-LYMPHOCYTIC SERUM

Skin allografts survived longer on ALS-treated, complement-deficient (C5 negative) recipients than on ALS-treated, complement-competent (C5 positive) recipients. Administration of C5-positive serum to C5-negative, ALS-treated recipients resulted in reduced graft survival. A percentage of grafts from ALS-treated, C5-positive donors was rejected when transferred to untreated syngeneic recipients; this was not observed when C5-negative, syngeneic animals served as ALS-treated donors and untreated recipients. It was concluded that ALS has graft-rejecting properties which are promoted by late acting complement components. Unlike ALS-mediated graft rejection, ALS-mediated immunosuppression appeared to be independent of the late acting complement components. The effect of ALS on the humoral response to sheep erythrocytes was examined in complement-deficient and complement-competent mice. Immune-suppression was determined by ALS treatment of C5-competent and C5-deficient mice and also by transfer of in vitro ALS-treated spleen cells from C5-negative and C5-positive donors to cyclophosphamide-treated recipients. The ability of ALS to depress the humoral response to sheep cells and to decrease immunological competence of spleen cells was the same in the presence as in the absence of C5