The procedure begins with the absorption of non-specific antibodies using an extract from non-pathogenic treponemes, which minimizes cross-reactivity. The patient's serum is then incubated with a slide pre-coated with Treponema pallidum antigens. After washing to remove unbound antibodies, a fluorescent-labeled anti-human immunoglobulin antibody is applied. If Treponema pallidum antibodies are present, they will bind to the antigen and fluoresce under a microscope.
