Abstract: Synthetic immunomodulatory molecules having a .gamma.-L-glutamyl-, a .gamma.-D-glutamyl, a .beta.-L-aspartyl, or a .beta.-D-aspartyl moiety at the amino terminus are provided as illustrated by Formula A. In Formula A, "n" is 1 or 2, R is hydrogen, acyl or alkyl, and X is an aromatic or heterocyclic amino acid or its derivative. A particularly preferred embodiment is .gamma.-D-glutamyl-L-tryptophan, which has immunomodulatory activity.

Abstract: The new class of synthetic immunomodulatory molecules having a .gamma.-L-glutamyl- moiety at the amino terminus are provided as illustrated by Formula 1. ##STR1## In Formula 1, the Greek symbols designate the noted carbon atoms, R is hydrogen, acyl or alkyl, and X is an aromatic or heterocyclic amino acid or its derivative. Included as members of the new class (in addition to Bestim, .gamma.-L-glutamyl-L-tryptophan) are those compounds where R=hydrogen and X=L-tryptophan, such as .gamma.-L-glutamyl-N.sub.in -formyl-L-tryptophan, N-methyl-.gamma.-L-glutamyl-L-tryptophan, N-acetyl-.gamma.-L-glutamyl-L-tryptophan, and .gamma.-L-glutamyl-.beta.-thienyl-D-alanylamide. A preferred embodiment, termed "BESTIM," has the chemical structure of .gamma.-L-glutamyl-L-tryptophan.