Concanavalin A inhibits the development of experimental allergic encephalomyelitis in guinea pigs.

The effect of concanavalin A (Con A) on experimental allergic encephalomyelitis (EAE) was assessed in guinea pigs with a various time, dose and route schedule. EAE was significantly suppressed when 5 mg of Con A was injected in the sensitizing injection sites within 3 days before or after sensitization with bovine spinal cord in complete Freund's adjuvant. The EAE-suppressive activity of Con A was shown by significant reductions in incidence and severity of EAE, a delayed onset of EAE and low mortality. The proliferative response of draining lymph node cells (LNC) to myelin basic protein (BP), the growth of the draining lymph nodes (LN) and the proliferation of active rosette-forming T cells in the draining LN were all significantly suppressed in Con A-treated animals than those of unsuppressed animals. The depressed LNC reactivity to BP in Con A-treated animals was not increased when nylon wool adherent cells were removed, whereas there was a significant increase in unsuppressed animals. These results suggest that Con A suppressed EAE by inhibiting the proliferation of BP-sensitized T cells in the draining LN and that the interaction between T cell subsets could exert an inhibitory effect on EAE.