Mitochondrial and other tissue autoantibodies in patients with biological false positive reactions for syphilis.

Mitochondrial antibodies (M' fluorescence) similar to those seen in patients with primary biliary cirrhosis but of low titre and predominantly of IgM class were found in 51% of forty-one patients showing chronic false positive reactions for syphilis, in the absence of detectable liver abnormalities. The pathogenic significance of this association is not understood but the antigen of Wasserman reaction and Venereal Disease Research Laboratory tests, cardiolipin, is situated in close proximity to the distinct lipoprotein reactive in M' fluorescence, both being components of the mitochondrial inner membranes. Since these two antibodies have a low incidence in the population, it is likely that their association in a highly selected group of patients represents a particular immunological abnormality in the context of the collagenoses. Thus four of the cases presented with unusual neurological features. The presence of `M' fluorescence in biological false positive reactors was strongly correlated with systemic disease. This test, together with those for antinuclear and other tissue antibodies may prove of help in differentiating unusual variants of connective tissue disorders and in the follow-up of symptomless patients who are liable to develop these diseases in later life.