title: Inhibition of the cellular immune response to simian virus 40 tumor cells in tumor-bearing and tumor-immune mice by concanavalin A.
abstract: The effects of in vivo-administered concanavalin A (Con A) on the kinetics of the primary and secondary cellular immune responses to simian virus 40-transformed tumor cells were investigated in BALB/c mice. Either a single initial dose of 400 mug Con A or daily doses of 50 mug depressed the cell-mediated immune response to tumor cells during the progressive growth of tumors, as determined by a radioisotopic foot-pad assay. The immune depression correlated with an increase in ultimate tumor weight. Similarly, Con A suppressed the antitumor cellular immune response in tumor-immune animals. Immune reactivity returned within 6 days after a single injection of 400 mug Con. Continuous administration 50 mug Con A resulted in a gradual decline in antitumor cellular immune responsiveness, which reached a plateau by the 5th day. Splenic lymphocytes from Con A-treated, immune mice failed to elicit a local adoptive transfer reaction; their immune responsiveness tended to return after incubation with alpha-methyl-D-pyranosyl sugars.
mesh_terms: D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology*; D005354:Fibrosarcoma / Q000209:etiology / Q000276:immunology*; D007111:Immunity, Cellular / Q000187:drug effects*; D007116:Immunization, Passive; D007700:Kinetics; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D012513:Sarcoma, Experimental / Q000209:etiology / Q000276:immunology; D013539:Simian virus 40; D013154:Spleen / Q000166:cytology; D013997:Time Factors
chemical_list: D003208:Concanavalin A