MASPAT is a solid-phase microwell plate system for the detection of platelet antibodies (anti-HLA and anti-HPA) in serum by testing donor platelets with patient serum in a crossmatching assay.
The principle of the test is the solid phase technique, which is based on antigen/antibody reaction. A monolayer of donor platelets is immobilised by centrifugation onto the surface of the microplate wells coated with platelet-specific mouse monoclonal antibody.
Patient serum and LISS (Low Ionic Strength Solution) are incubated in the appropriate wells, allowing serum antibodies to bind to the immobilised platelet monolayer. After incubation, non-bound serum components are removed by washing. Platelet-bound antibodies are detected by the addition of mouse monoclonal anti-human IgG and human IgG-sensitised erythrocytes (MASPAT Indicator Red Cells) and subsequent centrifugation of the microplate.
In case of a positive reaction the anti-human IgG and MASPAT Indicator Red Cells bind to the IgG-antibodies on the platelet monolayer. Positive reactions are thus characterised by adherence of indicator red blood cells throughout the surface of the wells, whereas negative reactions produce discrete pellets of Indicator Red Cells in the middle of the well.
It is the general experience that in a significant proportion of HLA-matched platelet transfusions administered to allo-immunised patients a satisfying rise in platelet count remains absent. This is caused by platelet specific antibodies (HPA).