title: Elicitation of the reproduction-inhibiting antibody ablastin by serum exoantigens of Trypanosoma lewisi.
abstract: Serum exoantigens of Trypanosoma lewisi were collected 5 days after infection from immunocompetent (untreated) rats and rats immunosuppressed by treatment with either hydrocortisone acetate or dexamethasone. Normal rats were then immunized with pooled, whole exoantigen-containing serum from 1 of these 3 sources plus alum as an adjuvant, and the immune sera produced were tested individually. All contained agglutinating (trypanocidal) antibodies to both antigenic variants of T. lewisi, but only about two-thirds showed precipitating activity with exoantigens in gels. More importantly, however, when these antisera were thoroughly adsorbed with living trypanosomes (from immunocompetent hosts) to remove agglutinating antibody only and then tested for ablastic activity in vitro, all showed significant (P less than 0.01) reproduction-inhibiting activity, comparable to that shown by ablastic serum collected from rats that experienced a natural infection. Antisera from control rats similarly immunized with normal rat serum were negative in all antibody tests. The exoantigens of T. lewisi are, therefore, a complex mixture of immunogens that are related to the known immune responses to the parasite and can elicit the formation of ablastic antibody with the same biological properties as that produced during a natural infection.
mesh_terms: D000373:Agglutinins / Q000032:analysis; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D005260:Female; D007114:Immunization; D007074:Immunoglobulin G / Q000096:biosynthesis*; D011234:Precipitins / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D014350:Trypanosoma lewisi / Q000276:immunology*
chemical_list: D000373:Agglutinins; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D011234:Precipitins; C019230:ablastin