There are disclosed compound of formula I, in which R1 represents a hydrophobic moiety adapted to occupy the C′ channel of human CDId, R2 represents a hydrophobic moiety adapted to occupy the A′ channel of human CDId, such that R1 fills at least at least 30% of the occupied volume of the C′ channel compared to the volume occupied by the terminal nC14H29 of the sphingosine chain of α-galactosylceramide when bound to human CDId and R2 fills at least 30% of the occupied volume of the A′ channel compared to the volume occupied by the terminal nC25H51 of the acyl chain of α-galactosylceramide when bound to human CDId R3 represents hydrogen or OH, Ra and Rb each represent hydrogen and in addition, when R3 represents hydrogen, Ra and Rb together may form a single bond, X represents or —CHA(CHOH)nY or —P(=0)(0−)0CH2(CH0H)mY, in which Y represents CHB1B2, n represents an integer from 1 to 4, m represents 0 or 1, A årepresents hydrogen, one of B1 and B2 represents H, OH or phenyl, and the other represents hydrogen or one of B1 and B2 represents hydroxyl and the other represents phenyl, in addition, when n represents 4, then A together with one of B1 and B2 together forms a single bond and the other of B1 and B2 represents H, OH or OSO3H and pharmaceutically acceptable salts thereof; the compounds of formula I are indicted for use in the treatment of a virus, microbial infection, parasite, an autoimmune disease, cancer, allergy or asthma.