ELISA procedures for the characterization of platelet specific antibodies. Evaluation of some variables

Characterization of antiplatelet antibodies is often difficult.

Four similar ELISA procedures for the characterization of the glycoprotein specificity of antiplatelet antibodies were compared.

The four techniques gave overlapping results when tested on thirty-five patients' sera containing antiplatelet antibodies. With ten sera the four procedures gave slightly dissimilar results. All the discrepancies consisted of incomplete glycoprotein identification with partial loss of complete glycoprotein complex recognition.

The analysis of the main technical variables led to the following conclusions: a) in some case antiplatelet antibodies recognize non-glycoproteic moieties of the platelet membrane (glyco- and phospholipids): the negative results found when investigating glycoprotein targets were the correct ones; b) the solubilization of unsensitized glycoproteins possibly leads to conformational changes able to mask the antigenic sites, while previous sensitization confers more stability to the molecule; c) best results were obtained using anti-mouse IgG as capturing agent for sensitized glycoproteins: it is likely that this antibody let a larger number of binding sites available for the second antibody.