Treponema pallidum particle agglutination assay
The TPHA ( Treponema pallidum hemagglutination - assay) is a test specifically for infection with syphilis specifically leads to an indirect detection by, by examining the patient's serum for antibodies to Treponema pallidum ( the causative agent of syphilis).
It is erythrocytes (red blood cells), on the surface thereof have been " fixed " proteins and polysaccharides of Treponema pallidum. Now the patient serum happen. If it contains antibodies against Treponema pallidum, they will bind to the above-mentioned proteins or polysaccharides to erythrocytes, and this networked. This networking can be seen with the naked eye as a clumping of red blood cells (hence the term hemagglutination ). The patient serum contains no antibodies, the erythrocytes are simply settle. This, too, is macroscopically visible.
If this screening test is positive, you make another control with the so-called FTA -Abs test.
At a false positive test result, it comes through the antiphospholipid syndrome. The thus formed antiphospholipid antibodies also bind to cardiolipins the cell membrane of Treponema pallidum. This results in a false positive test result in the form of clumping of the erythrocytes.