Fig. 1

Detection of antibodies against granulocytes by indirect immunofluorescence*. A Positive: patient serum and drug. B Negative: patient serum without drug. C Negative: control serum and drug. *Fixed donor granulocytes are incubated with patient serum in the presence (A) or absence (B) of the suspected drug. After washing in the presence of the drug, a fluorescence-labeled secondary antibody is used to detect drug-specific antibodies bound to the cell surface. Cells are assessed under a fluorescence microscope against appropriate controls. The test is positive if antibodies are detected in the presence of metamizole or its metabolites [30]