Passive Antifibrinolytic Immunity. ∗

Abstract

As a preliminary to a study of passive antifibrinolytic immunity in laboratory animals, 5% high-titer commercial antistreptococcus serum† was added to freshly-drawn rabbit and rhesus bloods. The resulting passively immunized bloods were allowed to coagulate and serums separate. It was found that within the limits of the experimental error, the specific commercial antibody (“horse globulins”) could be demonstrated quantitatively 1 in the resulting passively immunized serums, even after 30 days storage in the ice-chest.

Seven rabbits were then injected intravenously with 5% of their calculated blood volumes of the same antistreptococcus serum. Blood samples were withdrawn at the end of 15 minutes, 90 minutes and at stated intervals during the next 30 days. The serums from these samples were titrated for antihuman antistreptofibrinolysin, a scarlatinal strain of streptococcus and purified human fibrin being used in the technic. Ten percent of the same commercial antiserum plus 90% normal rabbit serum was used as the control. Composite data thus obtained are recorded in A, Fig. 1.

From this figure it is seen that the maximum humoral titer of the passively immunized rabbits never exceeded 60% of that of the test-tube control. Forty percent of the “horse globulin” was apparently bound, denatured or otherwise inactivated within 15 minutes after intravenous injection. This passive titer fell to 4076 by the 11th hour, 10% by the 48th hour, and 5% by the 6th day.

The antistreptococcus serum selected for the above tests contains approximately equal amounts of 2 antifibrinolytic agents. One of these specifically neutralizes antihuman-rhesus streptofibrinolysin. The other is equally specific for antihorse streptolysin. 2 Passive immunization of 3 monkeys was studied with both of these simultaneously injected antibodies, “horse-strangles” streptococci and purified horse fibrin being used in the veterinary titration. Composite data thus obtained are recorded in B and B′, Fig. 1.