In vivo and in vitro immunological cross‐reactions between basic encephalitogen and synthetic basic polypeptides capable of suppressing experimental allergic encephalomyelitis

Abstract

AbstractA significant extent of immunological cross‐reactivity has been demonstrated between the basic encephalitogenic protein of bovine origin and several synthetic amino acid copolymers which have suppressive effect on experimental allergic encephalomyelitis (EAE). This cross‐reactivity has been conclusively established on the cellular level, both in vivo by means of delayed hypersensitivity skin tests and in vitro using transformation of sensitized lymphocytes, as measured by incorporation of radioactive thymidine. The in vitro experiments have been conducted with lymph node cells from guinea pigs of both random bred and inbred strains, and on spleen and lymph node cells from rabbits. Definite cross‐reactivity was observed between the basic encephalitogen and all the synthetic copolymers which were previously shown effective in suppression of EAE, whereas ineffective copolymers or unrelated proteins did not show any cross‐reactivity. In the case of strain 2 guinea pigs and rabbit lymph node cells the cross‐reactivity in vitro was manifested by direct cross‐stimulation of the lymphocytes, whereas in random‐bred or strain 13 guinea pigs and rabbit spleen cells, the cross‐reaction was detected only by means of specific inhibition of the homologous stimulation by the heterologous antigen.A limited extent of cross‐reactivity was observed on the humoral level as well; antibodies provoked in guinea pigs against the synthetic copolymer Cop 1 cross‐reacted in the passive cutaneous anaphylaxis assay with the bovine basic encephalitogen.