The RPR test is a non-treponemal serological test used to detect antibodies produced in response to Treponema pallidum, the bacterium that causes syphilis. It's a qualitative test, meaning it gives a positive or negative result. The RPR test is typically performed on serum or plasma obtained from a blood sample. In the RPR test, the patient's serum or plasma is mixed with a solution containing cardiolipin, lecithin, and cholesterol particles. If the patient's serum contains antibodies against Treponema pallidum, these antibodies will react with the cardiolipin-lecithin-cholesterol particles, causing visible agglutination or clumping. The RPR card is a specialized card or slide designed to perform the RPR test. It typically contains multiple wells or spots where the serum/plasma sample and the reagent are mixed, allowing for easy observation of agglutination reactions. These cards are convenient for laboratory use, enabling multiple samples to be tested simultaneously and facilitating the interpretation of results.