Test principle, storage, sample material, interference
Pyruvate kinase is a key enzyme in glucose metabolism and exists in various isoforms. In its active form, it consists of four equal subunits (tetramer). When a tumor develops, the tissue-specific isoenzymes are lost and expression of the M2 form of isoenzyme occurs. The amount of M2-PK increases and the isoenzyme that originally consisted of four subunits is split into a low-activity form consisting of two subunits (dimer). The dimeric form is generally detectable in large amounts in tumor cells.
The ScheBo® • M2-PK Quick™ stool test is based on an immunochromatographic method. The M2-PK is detected by two specific monoclonal antibodies. M2-PK in the stool sample reacts with a monoclonal antibody bound to gold particles. This complex migrates along the membrane and reaches the test line to which a second monoclonal antibody against M2-PK is attached.
When the result is positive, the gold-labeled antibody-M2-PK complex binds to the test line and a pink color develops. When the result is negative, the sample does not contain any antibody-M2-PK complex that can bind to the test line and so no color becomes visible. Development of a pink control line guarantees that sample application and migration have taken place correctly and that the test was properly performed.