Delayed Hypersensitivity to Soluble Antigens in Mice

Abstract

Delayed hypersensitivity to a soluble protein has been analyzed in vitro with lymph node cells from mice. Antigen-dependent cytotoxicity against innocent bystander cells, and incorporation of tritiated thymidine have been used to monitor the response to a subcutaneous tail injection of egg albumin (OVA) in complete Freund’s adjuvant. Sensitized lymph node cells from mice with positive 24 h ear tests killed A9 cells in the presence of antigen. This antigen-specific, T cell-mediated cytotoxicity was observed within 4 days of sensitization and still apparent at 7 months. Reactivity to OVA, assessed as an increase in DNA synthesis in the presence of antigen, was also T cell dependent and exhibited similar sensitization kinetics and dose requirements. Both microtechniques require as few as 10⁵ lymphocytes and are readily adaptable to the study of delayed hypersensitivity to any soluble protein in mice.