Simultaneous detection of platelet and lymphocyte antibodies by slide enzyme immunoassay

The feasibility of using an enzyme immunoassay (EIA) to detect simultaneously the antibodies bound to platelets and lymphocytes on glass slides was investigated. A peroxidase-antiperoxidase (PAP) immune complex method was used in which lymphocytes and platelets were attached to glass slides by poly-L-lysine and the preparations were stored at -20 degrees C for subsequent assays. Test sera were incubated with the cells. Reagents linking the platelet and/or leukocyte antibody to the PAP enzyme marker were added, followed by a staining step to localize the antigen-antibody complex. Any brown staining of the perimeter of the cells and in the cytoplasm was considered indicative of a positive reaction. A total of 146 sera were assayed; 36 were from Roswell Park Memorial Institute (RPMI) plasmapheresis donors, 75 were from RPMI oncology patients, and 35 were from other laboratories. The PAP method agreed with complement lysis inhibition assay (CLIA) by 97 percent in detecting antibodies capable of reacting with platelets while concordance with complement dependent lymphocytotoxicity (CDL) was 81 percent. With further investigation, this method could be adapted as a screening procedure in the clinical laboratory. It is easy, inexpensive, and could be performed in a few hours.