LIAISON (R) TPA, the automated chemiluminescence immunoassay for the determination of cytokeratins 8, 18 and 19

TPA is a circulating complex composed of polypeptide fragments of the cytok eratins 8, 18 and 19. Serum TPA is a well-established marker for tumours ar ising from epithelial cells. The levels have been shown to correlate with t he extent of the disease, and TPA is a valuable parameter for monitoring an d followup of carcinomas of the lung, breast, colorectum and urinary bladde r. LIAISON(R) TPA is a rapid and fully automated immunoassay analyser from Byk -Sangtec. LIAISON(R) is based on paramagnetic particles as solid phase. The tracer antibody is labelled with an isoluminol derivative. The assay uses the same three monoclonal antibodies as the reference method TPA-M IRMA. Th e paramagnetic particles are coated with three monoclonal antibodies to cyt okeratins 8, 18 and 19 and the tracer is based on a polyclonal anti-cytoker atin 8, 18 and 19. The assay is a two-step sandwich immunoassay with a tota l incubation time of 20 minutes. The measuring range of the assay is from the analytical sensitivity of 10 U /L to 4 000 U/L. Typical within-assay precision is below 6%. The agreement between LIAISON(R)TPA and TPA-M IRMA is shown by a correlation coefficient of 0.97 and a slope of 1.12 for a group of 250 mixed cancer patients. The c ut-off value, based on 200 blood donor serum samples, is 69 U/L. TPA is a r eliable marker not only in colorectal and bladder cancer, it is also a reli able marker in breast and lung cancer. At a specificity of 95%, TPA has sho wn a sensitivity of 24% in a group of breast cancer patients. In the same s tudy, CEA and CA15-3 showed sensitivities of 20% and 12% respectively. In l ung cancer, TPA has shown a sensitivity of 23% (at 95% specificity), compar ed to 17% for Cyfra 21-1. TPA is a marker with superior sensitivity in many different cancers, and th e new LIAISON(R) offers a precise, rapid and reliable method for determinat ion of this marker.