Anaphylaxis to viscotoxins of mistletoe (Viscum album) extracts.
BACKGROUND
Extracts of mistletoe (Viscum album) are used in many countries for adjuvant cancer therapy. These extracts contain mistletoe lectins and viscotoxins that are supposed to have immunostimulating and cytotoxic effects, respectively. The treatment is usually well tolerated.


OBJECTIVE
To report a case of severe anaphylaxis secondary to mistletoe extract administration with demonstrable anti-IgE antibodies to mistletoe.


METHODS
Skin prick tests, basophil histamine release, basophil activation test, and immunoblotting were performed to characterize the pathophysiology of this reaction.


RESULTS
The patient had immediate-type skin prick test reactions to the whole commercial preparation and to its mistletoe extract component. A histamine release test and a flow cytometric basophil activation test performed with the patient's peripheral blood leukocytes by incubation with the mistletoe extract yielded a concentration-dependent histamine release and expression of the activation marker gp53 in up to 98% of anti-IgE-positive cells. Immunoblotting revealed IgE binding to 5-kDa proteins of mistletoe in the patient's serum, which corresponds to the molecular weight of viscotoxins. The results of all these tests were negative in controls.


CONCLUSIONS
Until now, anaphylaxis to mistletoe extracts has been only rarely reported. In our patient, viscotoxin specific IgE evidently had induced an anaphylactic reaction.
Bauer
Carolyn
C
Klinik und Poliklinik für Dermatologie und Allergologie, Ludwig-Maximilians-Universität, Munich, Germany. Carolyn.Bauer@derma.med.uni-muenchen.de
Oppel
Tilmann
T
Ruëff
Franziska
F
Przybilla
Bernhard
B
D000707:Anaphylaxis / Q000139:chemically induced* / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000097:blood; D008213:Lymphocyte Activation / Q000187:drug effects; D008875:Middle Aged; D014784:Mistletoe / Q000009:adverse effects* / Q000276:immunology; D010940:Plant Proteins / Q000009:adverse effects* / Q000276:immunology; D012882:Skin Tests
D010940:Plant Proteins; D007073:Immunoglobulin E; C488038:viscotoxin