Reappraisal of lymphocyte responsiveness to concanavalin A during experimental syphilis: evidence that glycosaminoglycans in the sera and tissues interfere ith active binding sites on the lectin and not with the lymphocytes.

No significant differences were noted between the responses of lymphocytes from normal and Treponema pallidum-infected rabbits to concanavalin A. When added to cultures of normal peripheral blood lymphocytes, however, sera and tissue supernatant fluids from infected rabbits were capable of suppressing the response to concanavalin A. Although immune complexes were regularly present in suppressive sera and tissue extracts, additional experiments in which both direct and indirect approaches were used indicated that immune complexes were not responsible for the observed depression. Sequential stimulation studies, done with purified glycosaminoglycan materials obtained from suppressive sera and testicular fluids, and specific absorption studies suggested that this material blocks active sites on the lectin and merely prevents recognition of the mitogen by otherwise functionally active cells.