A Simple Immunofluorescence Test for the Detection of Platelet Antibodies

TLDR

Platelet immunofluorescence tests are limited by nonspecific fluorescence from plasma protein binding to the platelet membrane. The study developed the platelet suspension immunofluorescence test (PSIFT) using PFA‑fixed platelets to detect platelet antibodies. PSIFT employs PFA‑fixed platelets and a continuous‑flow microfluorometer to measure platelet immunofluorescence, enabling quantitative antibody and antigen assessment. PFA fixation eliminates nonspecific fluorescence without affecting platelet antigens, allowing PSIFT to detect various platelet‑reactive antibodies (IgM agglutinins, IgG non‑agglutinins, drug‑dependent, HLA, anti‑A/B) with satisfactory sensitivity and reproducibility.

Abstract

Immunofluorescence tests on platelets have always been hampered by nonspecific fluorescence caused by non‐immunological binding of plasma proteins to the platelet membrane. It was found that this could be easily overcome by fixation of the cells with paraformaldehyde (PFA). By using PFA‐fixed platelets, a simple method for the detection of platelet antibodies, the platelet suspension immunofluorescence test (PSIFT) was developed. PFA fixation did not alter or inactivate the platelet antigens tested. Platelet‐reactive antibodies detected specifically with the PSIFT included platelet‐specific agglutinins of the IgM class, non‐agglutinating platelet‐specific antibodies of the IgG class, drug‐dependent platelet antibodies, HLA antibodies, as well as anti‐A and anti‐B antibodies. The sensitivity of the new test was satisfactory, as was its reproducibility. Measurement of platelet immunofluorescence was possible in a continuous flow microfluorometer, making in principle, quantitation of platelet antibodies and antigens possible.