Suppression of cell-mediated immune responses by dextran sulphate.

The effect of high molecular weight dextran sulphate (DS) on cell-mediated immune responses was studied. Two criteria were used to assess cell-mediated responses, skin graft rejection and intra-dermal (i.d.) skin tests. Mice receiving allografts and DS displayed a significant increase in graft survival time compared with untreated control animals. Similar results were obtained when the grafted animals differed at only the H-Y locus. Guinea-pigs sensitized with Mycobacterium tuberculosis and treated with DS showed a greatly reduced delayed skin test response when challenged with purified protein derivative. DS was capable of suppressing this response even though, by the same route, dosage, and time of administration, it was previously shown to enhance a cell-mediated response in guinea-pigs sensitized with a different antigen. The results of this study indicate that the adjuvant DS is capable of suppressing cell-mediated immune responses in mice and guinea-pigs.