antigen used in RPR Test:
RPR Antigen contains cardiolipin, lecithin, cholesterol, 10% choline chloride, EDTA, charcoal etc in Buffer.
The antigen is prepared from a modified Venereal Disease Research Laboratory (VDRL) antigen suspension containing choline chloride to eliminate the need to heat inactivate serum, ethylenediaminetetraacetic acid (EDTA) to enhance the stability of the suspension, and finely divided charcoal particles as a visualizing agent.
Positive Control: Prepared from human serum samples containing antibodies to Treponema pallidum. Serum is ready to use. Bring to room temp before use.
The test kits can be purchased from many commercial sources.
Basic Test Procedure
RPR antigen is mixed with unheated or heated (to inactivate complement) serum or with unheated plasma on a plastic-coated card.
If antibodies are present, they combine with the lipid particles of the antigen, causing them to agglutinate. The charcoal particles coagglutinate with the antibodies and show up as black clumps against the white card (macroscopically visible flocculation-type precipitation if the patient’s sera contains reagin).
Without some other evidence for the diagnosis of syphilis, even a reactive nontreponemal test does not confirm T. pallidum infection and treponemal tests such as Treponema pallidum haemagglutination assay (TPHA) or Fluorescent Treponemal Absorbtion Test (FTAbs) must be done to confirm the syphilis.
If antibodies are not present in the test serum, the test mixture is uniformly gray.