Taurine conjugation of arylacetic acids in the ferret.

reactivity. As anti-mitochondria1 antibodies can bind complement we used a complement-fixation test. Results from preliminary tests were difficult to interpret. The Paracoccus membranes had strong anti-complementary activity, which had to be diluted out. Also the sera available from patients with primary biliary cirrhosis were themselves anti-complementary up to quite high dilutions. Nevertheless, the sera tested did appear to demonstrate complement-fixing reactivity against both mitochondria1 membranes and Paracoccus membranes when compared with the corresponding normal serum controls. Further tests will be necessary to confirm the specificity of the reaction between Puracoccus denitrificans and sera from subjects with primary biliary cirrhosis. Corresponding tests are also clearly desirable with membranes from other aerobes and from anaerobes such as Streptococcus faecalis. These studies should also be extended to sera of mice immunized with syngeneic mitochondria (Davey et al., 1975) and to mice immunized with bacterial membrane preparations. Confirmation of a cross-reaction between anti-mitochondria1 antibody and bacterial membranes could throw new light on the nature of the mitochondrial antigen, and might also have implications as to alternative origins of anti-mitochondria1 activity in sera in human subjects.