Universal serologic reaction in leprosy.

It has long been known that the serum of certain leprosy patients gives positive reactions with tests for syphilis. These reactions have not been understood and have been interpreted as biologic ‘(false positives.” The reason for this interpretation undoubtedly lies in the widespread assumption that only in syphilis and in closely related diseases, such as yaws and bejel, are serum reactions with lipid antigen “true positives.” We, ourselves, held this assumption for a number of years. In due time, cumulative experimental findings in this laboratory suggested that serum reactions with lipid antigen in the absence of syphilis are biologically significant. The question then arose whether the reactions might also be significant clinically in different diseases. In attempting to answer this question, a multiquantitative precipitation technique with lipid antigen was devised and applied to healthy individuals, to animals, and to patients with syphilis, yaws, leprosy, malaria, and tuberculosis. It was found that all individuals and all animals, whether in health or disease, gave positive precipitation reactions when tested with this technique. This finding led to the use of the term (‘universal serologic reaction.’’ The basic characteristics of this reaction in health and in certain diseases will first be briefly reviewed. This step, it is believed, will help clarify the behavior of the reaction in leprosy. The universal serologic reaction is a precipitation reaction elicited with lipid antigen. It exhibits qualitative and quantitative precipitation properties. The qualitative property determines the serologic pattern of the reaction. The basis of the pattern is the arrangement of precipitation in relation to given NaCl concentrations and to periods of incubation employed in the universal serologic technique. The quantitative property determines the degree of precipitation in the reaction, a factor which is independent of the serologic pattern. Normal human beings give universal reactions of a characteristic serologic pattern. This pattern is believed to be the result of a precipitation reaction between natural auto-antibodies to lipids present in the serum and corresponding lipids present in the tissue extract antigen. These auto-antibodies are presumably formed in response to lipids, liberated in normal tissue wear and tear, which have antigenic properties. The degree of precipitation in^ the universal reaction generally varies in different normal individuals, but is constant in the same individual. The variations in precipitation in different individuals are presumably due to different concentrations of auto-antibodies in the serum. These d8erent concentrations are believed to be the result of differences in the liberation of antigenic lipids and in the capacities for antibody production. The relatively constant degree of precipitation in the same normal individual is