Immunotherapeutic agents

A compound of the formula:

• ##STR5## in which:
• (a) X is --O-- or --(C.sub.n H.sub.2n)-- in which n has a value of 0, 1, 2, or 3, and R.sup.1 is alkyl of one to 10 carbon atoms, monocycloalkyl of up to 10 carbon atoms, polycycloalkyl of up to 10 carbon atoms, or benzocyclic alkyl of up to 10 carbon atoms, or
• (b) X is --CH.dbd. and R.sup.1 is alkylidene of up to 10 carbon atoms, monocycloalkylidene of up to 10 carbon atoms, or bicycloalkylidene of up to 10 carbon atoms;
• R.sup.2 is hydrogen, nitro, cyano, trifluoromethyl, carbethoxy, carbomethoxy, carbopropoxy, acetyl, carbamoyl, acetoxy, carboxy, hydroxy, amino, lower alkyl, lower alkylidenemethyl, lower alkoxy, or halo;
• R.sup.3 is pyridyl, unsubstituted or substituted with 1 or more substituents each selected independently from the group consisting of nitro, cyano, halo, trifluoromethyl, carbethoxy, carbomethoxy, carbopropoxy, acetyl, carbamoyl, acetoxy, carboxy, hydroxy, amino, substituted amino, alkyl of 1 to 10 carbon atoms, alkoxy of 1 to 10 carbon atoms, or phenyl;
• each of R.sup.4 and R.sup.5 taken individually is hydrogen or R.sup.4 and R.sup.5 taken together are a carbon-carbon bond;
• Y is --COZ, --C.tbd.N, or lower alkyl of 1 to 5 carbon atoms;
• Z is --OH, --NR.sup.6 R.sup.6, --R.sup.7, or --OR.sup.7 ;
• R.sup.6 is hydrogen or lower alkyl;
• and
• R.sup.7 is alkyl or benzyl.