title: The immune response to oxidized ferredoxin. II. Cross reactivity of cells and antisera to modified ferredoxins and the nature of the cells responding in vitro.
abstract: The cross reactivity of sera from rabbits sensitized to performic acid oxidized ferredoxin (O-Fd) and of spleen cells from mice sensitized to O-Fd was analysed using several chemically modified forms of ferredoxin in the complement fixation test and the in vitro lymphocyte stimulation assay. Only O-Fd and native ferredoxin (native-Fd) gave positive responses in both assays. Dinitrophenylated-O-Fd (DNP-O-Fd) and acid precipitated ferredoxin (TCA-Fd) were able to fix complement (C') but did not simulate DNA synthesis in vitro. Ferredoxin alkylated with N-ethylmaleimioxin (CM-Fd) was unable to stimulate DNA synthesis and was marginally able to fix C'. Methylated-O-Fd (meth-O-Fd) was not recognized in either assay. The various ferredoxin preparations were tested for their ability to sensitize mice for use in the in vitro lymphocyte stimulation assay. Only O-Fd, NEM-Fd and native-Fd were capable of sensitizing lymphocytes for a proliferative response in vitro to the test antigens. This correlates with the observation that only these antigens were able to induce DNA synthesis in O-Fd-sensitized lymphocytes. The nature of the cells responding in vitro was examined by treating the cells with rabbit anti-mouse immunoglobulin and C' or rabbit anti-mouse brain associated theta and C'. The 24-hr response was found to be sensitive to both sera while the 120-hr response was sensitive only to the anti-theta sera.
mesh_terms: D000478:Alkylation; D000818:Animals; D003168:Complement Fixation Tests; D003429:Cross Reactions; D005288:Ferredoxins / Q000276:immunology*; D007111:Immunity, Cellular; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D051379:Mice; D010084:Oxidation-Reduction; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D005288:Ferredoxins