In vitro, as hemolysis proceeds, the total amount of amboceptor is constant but the stroma of the laked red cells increasing in amount, they become less and less saturated with amboceptor, and so split off less of it by dissociation, thus causing the velocity of hemolysis to decrease.
In vivo the stroma produce specific hemolytic and agglutinative bodies of high titer. Since little protein is injected the toxicity seems to be nil.
Alcohol and ether extracts, as well as 0.85 and 5 per cent salt solution extracts, of the stroma do not bind amboceptor in vitro.
The extract of stroma with alkaline physiological salt solution, as described above, does bind amboceptor in vitro and on injection causes the development of specific hemolysins but not of agglutinins.
This alkaline extract contains nucleo-protein, but not simple albumin or globulin. It also contains lipoids but these probably are not essential to its antigenic function.
The presence or absence of the anaphylactic reaction is not a certain criterion for specificity when nucleo-protei nsare used as antigens. In our work, hemolysins, showing species specificity, were present in the absence of anaphylaxis.