Pseudothrombocytopenia is due to platelet agglutination antibodies when the calcium content is decreased by blood EDTA. The antibody to cause this effect is mainly:
IgG is the most common antibody to cause platelet agglutination and cause pseudothrombocytopenia. Ref: Harrison Edition - 18, Page - 965
IgG
IgA
IgM
IgD