<h3>To the Editor:—</h3> The Journal(<b>201</b>: 562, 1967) published "Isohemagglutinins in Pooled Plasma" by K. B. McCall, PhD, who expressed surprise at the high titers reported by Oberman et al,<sup>1</sup>and stated that he had never observed a high titer (saline) plasma pool prepared by the Michigan Department of Health between 1943 and 1957 from outdated blood. He suggested that the higher titers noted by other workers may be the result of the newer methods of blood collection and plasma separation and that these gentler methods protect the red cells from disintegration, which presumably would liberate isohemagglutinogenic neutralizing substances A and B. However, Rutzky et al<sup>2</sup>reported high anti-A titers in commercially pooled plasma and stated "neither dilution in the pool nor neutralization by natural A substance in the component A plasmas can be relied upon." We have recently completed a study under National Institutes of Health Contract
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