Regulation of paralytic experimental allergic encephalomyelitis in rats: susceptibility to active and passive disease reinduction.

Spleen cells obtained from Lewis inbred rats previously immunized with 50 microgram of guinea pig basic protein emulsified in complete Freund's adjuvant passively transferred paralytic experimental allergic encephalomyelitis (EAE) only following an in vitro conditioning period. The in vitro conditioning required the presence of either concanavalin A or encephalitogenic antigen. The conditioned cells caused passive paralytic EAE in recipients of 10 million viable cells. After recovery from passive paralytic EAE, animals were completely susceptible to additional attempts to induce EAE by active or passive means. Active EAE recovered rats were resistant to additional attempts to induce active EAE but were fully susceptible to passively induced EAE mediated by in vitro conditioned cells.