The ABS suffix refers particularly to a processing step used to remove nonspecific antispirochetal antibodies present in normal serum.
The bacteria cannot be cultured on laboratory media, so the organisms used are a lyophilized suspension of T. pallidum extracted from rabbit testicular tissue.
Patient serum is mixed with an absorbent (the "ABS" part of the test) containing an extract of a non-pathogenic treponeme, Treponema phagedenis biotype Rieter.
The purpose of the absorbent is to remove anti-treponemal antibodies that are not specific for the syphilis bacteria.
[citation needed] This test is not useful for following therapy, because it does not wane with successful treatment of the disease, and will continue to be positive for many years after primary exposure.