Flow cytometry detection of autoantibodies reacting with specific platelet receptors. The kit contains an R-phycoerythrin (R-PE) conjugated monoclonal antibody, which recognizes a platelet specific antigen. The kit also contains polyclonal antibodies conjugated whit fluorescein isothiocyanate (FITC) against total human immunoglobulins, human IgA, IgM and IgG. The kit contains a polyclonal antibody conjugated whit FITC as a negative control.