For the detection of auto-antibodies on the platelets and in the serum of patients
with idiopathic thrombocytopenic purpura, three new techniques have recently been developed:
the quantitative antiglobulin consumption assay (QACA), the platelet radioactive antiglobulin
test (PRAT) and the platelet suspension immunofluorescence test (PSIFT). The
results obtained by various investigators with these techniques differ considerably. We, therefore,
studied the sensitivity of the three methods. This was done by testing platelet-reactive
allo-antibodies (anti-Zw^a, anti-HLA-A2) and auto-antibodies in titration.
The results show that the PSIFT is the most sensitive technique, closely followed by the
PRAT. The QACA was found to be much less sensitive than the other two methods. This
suggests that a positive result in the QACA and a negative result in the PSIFT and/or PRAT
cannot be attributed to the presence of platelet auto-antibodies.