The excerpt on Wired magazine of The Breakthrough by Charles Graeber has the following description of how James Allison found the T-cell receptor.
Suddenly it seemed so obvious: If Allision could rig up a way to compare B cells and T cells, devise a lab experiment that put one against the other and let their redundant surface proteins cancel each other out, the receptor should be the molecule that didn’t cancel out. Essentially, he was looking for a needle in a haystack, and his idea was to set fire to the haystack and sift the ashes—or as Allison puts it, “pick it out of the weeds.” Whatever was left would be the needle he was looking for.
It is a vivid metaphor. But the author does describe in more specific detail how the cancellation actually works. Can someone give such a description?