by Elena Csernok
Antineutrophil Cytoplasmatic Antibodies (ANCA) have gained a greater and greater importance since their discovery 20 years ago, for diagnostic methods as well as for the therapy of patients with systemic vasculitides such as Wegener's Granulomatosis (WG) or Microscopic Polyangiitis (MPA). ANCAs are a group of anitbodies directed against against parts of the white bloodcells. Autoantibodies as such are antibodies which the immune-sytem develops against the patient's own body. They have never been found in the blood of healthy people. Why such antibodies are formed we do not know yet. They seem, however, to play an important role in the origin of vasculitides.
In order to trace ANCAs in the blood immunofluorescence-micoscopy is often applied. White blood cells of healthy persons are specially prepared. Then dilluted blood of the patient is added. ANCAs contained in this blood will connect with the white blood cells. These, in a further step, will be made visible and will afterwards be recognisable under a microscope at their fluorescent colours. Two different ANCA-fluorescence-pattern are distinguished: the classical cANCAs and pANCAs discovered later on. (p stands for perinuklear, because those ANCA form a ring around the nucleus of the white blood cells.) cANCAs are found with Wegener's Granulomatosis and sometimes with Churg-Strauss-Syndrome, pANCA can be found with Microscopic Polyangiitis, rarely with Churg-Strauss-Syndrome and with Wegener's Granulomatosis. Other vasculitides don't show any ANCAs
Excellent knowledge and experience are absolutely required to judge the different ANCA-fluorescence-patterns correctly. Thus a survey of ANCA should be left to laboratories specialised for this task. To make a comparison of ANCA factors in the course of an illness it is very important to have the determination carried through by the same laboratory for every determination. A successfull medicative treatment leads to a decrease of ANCAs. in contrast a relapse of vasculitis is often preceded by an increase of ANCAs, even before the patient notices any effects. These changes of the ANCA profile have been observed especially with Wegener's Granulomatosis, less frequently with other vasculitides This makes ANCA-supervising so important beside the other blood tests! It depends on the momentary activity of the illness how often these examinations should be carried through. If the illness has been in remission for a long time it is sufficient to check ANCAs every three to six months.