It is well known that when plasmas obtained from individuals belonging to the different blood groups are pooled there is evident neutralization of the agglutinins in the pooled plasma. This neutralization of the agglutinins occurs between A and B agglutinogens present in solution in the plasma from groups A, B and AB and the anti-A and anti-B agglutinins from groups O, A and B.
The agglutinin titers in pooled plasma are believed to be sufficiently low so that pooled plasma can be administered intravenously in large amounts to individuals of any blood type without fear of causing serious reactions from possibly incompatible agglutinins. This is borne out by an extensive, worldwide experience by a great number of physicians in the therapeutic intravenous use of pooled plasma.
However, when this investigation was started there were no publications of the determination of the agglutinin titers in large numbers of pools of plasma
THALHIMER W, TAYLOR ES, Shaub TS. THE LOW AGGLUTININ TITER OF BOTH SMALL AND LARGE POOLS OF PLASMA. JAMA. 1945;128(4):277-279. doi:10.1001/jama.1945.02860210033008