The rapid plasma reagin test (RPR test or RPR titer) is a type of rapid diagnostic test that looks for non-specific

antibodies An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...

in the blood of the patient that may indicate an infection by

syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms depend on the stage it presents: primary, secondary, latent syphilis, latent or tertiary. The prim ...

or related non-venereal treponematoses. It is one of several nontreponemal tests for syphilis (along with the Wassermann test and the VDRL test). The term ''reagin'' means that this test does not look for antibodies against the bacterium itself, ''

Treponema pallidum ''Treponema pallidum'', formerly known as ''Spirochaeta pallida'', is a Microaerophile, microaerophilic, Gram-negative bacteria, gram-negative, spirochaete bacterium with subspecies that cause the diseases syphilis, bejel (also known as endemic ...

'', but rather for antibodies against substances released by cells when they are damaged by ''T. pallidum'' ( cardiolipin and

lecithin Lecithin ( ; from the Ancient Greek "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so ar ...

). Traditionally, syphilis serologic testing has been performed using a nontreponemal test (NTT) such as the RPR or VDRL test, with positive results then confirmed using a specific treponemal test (TT) such as TPPA or FTA-ABS. This method is endorsed by the U.S.

Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the National public health institutes, national public health agency of the United States. It is a Federal agencies of the United States, United States federal agency under the United S ...

(CDC) and is the standard in many parts of the world. After screening for syphilis, a titer can be used to track the progress of the disease over time and its response to therapy. __TOC__

Accuracy

The RPR test is an effective screening test that is very good at detecting syphilis in people without symptoms. The NTT screening tests should always be followed up by a more specific treponemal test. Tests based on

monoclonal antibodies A monoclonal antibody (mAb, more rarely called moAb) is an antibody produced from a Lineage (evolution), cell lineage made by cloning a unique white blood cell. All subsequent antibodies derived this way trace back to a unique parent cell. Mon ...

and

immunofluorescence Immunofluorescence (IF) is a light microscopy-based technique that allows detection and localization of a wide variety of target biomolecules within a cell or tissue at a quantitative level. The technique utilizes the binding specificity of anti ...

, including ''T. pallidum'' hemagglutination assay ( TPHA) and fluorescent treponemal antibody absorption ( FTA-ABS) are more specific and more expensive. Nontreponemal tests (NTT) measure levels of

immunoglobulin G Immunoglobulin G (IgG) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG ...

(IgG) and

immunoglobulin M Immunoglobulin M (IgM) is the largest of several isotypes of antibodies (also known as immunoglobulin) that are produced by vertebrates. IgM is the first antibody to appear in the response to initial exposure to an antigen; causing it to also ...

(IgM) antibodies produced by the host in response to lipoidal material (mostly cardiolipin) released from damaged host cells. It is also generally believed that some cardiolipin is released by the spirochetes.

Alternatives

Another test often used to screen for syphilis is the Venereal Disease Research Laboratory (VDRL) slide test. However, the RPR test is generally preferred due to its ease of use. Other types of tests are being evaluated as possible alternatives to standard manual RPR testing. One of these alternatives is a fully automated RPR syphilis analyzer. It also returns positive for other, non-venereal treponematoses. It has been recommended that a careful explanation of this fact be included with test results.

References

* * {{Clinical microbiology techniques Infectious disease blood tests