MASPAT for platelet cross-matching
The 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 cross-matching assay.
The principle of the test is the solid phase technique, which is based on antigen/antibody reaction. A monolayer of donor platelets is immobilized 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 immobilized 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-sensitized 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 characterized 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.
Thanks to the speed and simplicity of this method, most hospitals will be able to perform platelet antibody screening before routine platelet transfusions. But even in laboratories that do not have access to HLA-typed donor panels, MASPAT will provide important information.
It is the general experience that in a significant proportion of HLA-matched platelet transfusions administered to allo-immunised patients that a satisfying rise in platelet count remains absent. This is caused by platelet specific antibodies (HPA).