Abstract: Methods and compositions are provided for modulating the immune response to an antigen based upon the finding that the cell surface protein CD40 is a mammalian heat shock protein (hsp) receptor. Cell surface CD40 mediates the binding, cell signaling, and uptake of hsp and particularly hsp with antigen bound thereto. Methods are provided for modulating hsp-antigen uptake and an immune response to the antigen by altering CD40 expression, as well as utilizing CD40-binding fragments of mammalian hsp and muteins thereof for targeting antigens to CD40-expressing cells. Screening methods for agonists and antagonists of the CD40-hsp interaction are also provided.

Abstract: Ceramide derivatives of the following general formula ##STR1## are described, wherein the individual radicals have the following meanings:X=--NH or --CH.sub.2,R.sub.1 =H or C.sub.1-11 -alkyl,R.sub.2 =C.sub.2-9 -alkenyl, wherein the double bond is in .alpha. position to the OR.sub.3 groupR.sub.3 =H, C.sub.1-6 -alkyl or C.sub.1-6 -acyl andR.sub.4 =OH, C.sub.1-6 -alkoxy or morpholino.These ceramide derivatives represent inhibitors of the biosynthesis of sphingolipids.