RPR Carbon Antigen

The microparticulate carbon RPR antigen enhances the visual discrimination between reactive and nonreactive results. The reagin-type antibody binds with the antigen that is composed of a complex of cardiolipin, lecithin and cholesterol particles with activated charcoal. The result of this antigen-antibody reaction is macroscopic flocculation.

A reactive result is indicated by the presence of aggregates in the center or periphery of the test circle, ranging from slight to marked and intense. A nonreactive result will give a smooth gray appearance within the test circle or a button of nonaggregated carbon particles in the center of the circle, showing none of the clumping characteristics of a reactive result.