Dr. Zoltan demonstrating one of his key contributions to immunology, the Passive Cutaneous Anaphylaxis (PCA) reaction, in the 1960's. While at NYU, working with Baruj Benacerraf and others, he discovered the "carrier-effect," i.e., the same carrier protein for the foreign substance must be used in subsequent immunications to produce the maximum amount of antibodies; and the once controversial, but for now fundamental concept that there are different classes of antibodies with different biological properties. <p>Gil Quito, Colleague of Dr. Ovary