Anaphylaxis to Patent Blue V. II. A unique IgE-mediated reaction

Patent Blue V (PBV) is injected in order to map sentinel nodes during cancer staging procedures. Anaphylactic reactions, allegedly IgE antibody mediated, have been reported. The aim of the study was to explore the immunological mechanism of anaphylaxis to PBV.

PBV allergen threshold basophil sensitivity, CD-sens, was performed on cells from nine patients diagnosed as having had adverse reactions to PBV. The mechanisms of the CD-sens were studied by immunological and immuno-chemical methods.

Five of the nine patients had a positive CD-sens to PBV which was completely eliminated by washing the cells in phosphate buffered saline before allergen challenge. However, the positive CD-sens was completely reconstituted by incubating the cells in plasma or serum of that patient or the other PBV-anaphylactic patients for 15 min at room temperature. In some patients the factor mediating CD-sens was completely or partially destroyed by heating at +56 degrees C for 30 min or being exposed to the low pH used for elution from anti-Ig columns. A 1000-fold excess of monoclonal IgE blocked the reconstitution by approximately 50%.

Anaphylactic reactions to PBV are mediated by IgE antibodies giving a classical CD-sens reaction. However, the allergenic configuration seems to constitute a structure completely dependent on PBV, as a hapten, linked to a, so far, unknown carrier that seems to be unique for patients having experienced a PBV-induced reaction. Further studies are needed to characterize the postulated carrier.