"If you're not into receptors, you may as well pack up and go home." The whispered remark, overheard at an assembly of endocrinologists, could have just as easily been passed at a gathering of immunologists, oncologists or—as the preceding editorial by Bell and Malick clearly illustrates—of clinical pharmacologists. Receptors are the "in" thing in medicine of the 1970's.
It is not too long since "receptors" were hypothetical constructs in Ehrlich "side-chain" theory of immunity (1885). They were conceived as a part of a cell that combines with and anchors a haptophore group of a toxin, which is neutralized when the receptor-containing side-chain is cast off into the circulation.
No longer linked to the outdated theory and no longer hypothetical—many have been characterized, identified, and isolated —receptors have been frequently shown to be more than mere passive recipients of exogenous or endogenous substances. The process is often that of interaction with