The alloimmunogenicity of heated blood and lymphoid cells

Murine lymph node cells heated to 45°C for 1 h or 56°C for 15 min lost their ability to provoke a primary cytotoxic alloantibody response, though they were able to provoke a secondary response in animals primed with normal lymph node cells two months previously. The primary immunogenicity of whole blood and spleen cell preparations was destroyed by 56°C but not by 45°C treatment. Treatment of spleen cells with 45°C heat, and ammonium chloride to remove red cells, destroyed their immunogenicity, whereas ammonium chloride treatment alone did not, suggesting that the red cells were the immunogenic component of heated spleen cells and, by implication, of blood. Further evidence for a difference in the immunogenicity of 45°C heated blood and normal blood was provided by the finding that heated blood did not prime for a response to 45°C lymph node cells given two months later. Preliminary investigations of the tolerogenicity of heated cells were unsuccessful, indicating, in view of the published data, that the precise protocol for tolerance induction is very critical.