Effect of levan on the stages of development of experimental allergic encephalomyelitis.

Experimental allergic encephalomyelitis was induced in male guinea pigs of the N13 strain by inoculation of an emulsion of basic protein of myelin with complete Freund's adjuvant. The disease was also passively transferred to other animals of the same strain by i.p. injection of sensitized lymphocytes obtained from donors inoculated with the antigenic emulsion eight days previously. Daily administration of levan markedly reduced the incidence and severity of the disease in actively sensitized animals. Little, if any, effect was obtained by levan treatment of animals with the passively transferred disease. The findings indicate that the previously reported inhibitory effect of levan on the development of experimental allergic encephalomyelitis is probably due mainly to a derangement of the afferent path (stage of sensitization). Administration of levan also causes a depletion of lymphocytes in the lymph nodes and this may presumably also affect the efferent path.