Br J Ophthalmol 2000;84:1004-1007
( September )
Topical ophthalmic 
blockers may cause release of histamine
through cytotoxic effects on inflammatory cells
Luc M van Beeka b, Marcel Mulderc, Nicolaas J van Haeringenb, Aize Kijlstrab d e
a Department of
Ophthalmology, Leiden University Medical Centre, Netherlands, b Netherlands Ophthalmic Research
Institute, Netherlands, c Department of Allergy, CLB
and Laboratory for Experimental and Clinical Immunology, Academic
Medical Centre, University of Amsterdam, Netherlands, d Department
of Ophthalmology, e Institute
for Animal Science and Health, Lelystad, Netherlands
Correspondence to: Dr L M van Beek, Department of
Ophthalmology, Leiden University Medical Centre, P O Box 9600, 2300 RC Leiden, Netherlands l.m.van_beek{at}lumc.nl
Accepted for publication 26 April 2000
AIM
To evaluate the
effects of 
blockers used in ophthalmology on the release of
histamine from mixed cell preparations containing human leucocytes and basophils.
METHODSA mixed
leucocyte and basophil preparation was obtained from venous blood of
healthy non-atopic volunteers. Cell preparations were then incubated
with betaxolol, metipranolol, timolol, or carteolol. After incubation
for 1 hour the histamine content of the supernatant was analysed by
automated fluorometric analysis. Cell viability was tested by measuring
lactate dehydrogenase (LDH) concentrations.
RESULTSBetaxolol and
metipranolol in concentrations between 10-2 M and
10-3 M liberated histamine from human blood cells in a
dose dependent manner. Carteolol and timolol had no effect on histamine
at these concentrations. At the same concentrations LDH was also
detected in the supernatants of cell suspensions incubated with
metipranolol or betaxolol.
CONCLUSIONSBetaxolol
and metipranolol induce substantial histamine release from human
leucocytes, probably as a result of their cytotoxic effect.
© 2000 by British Journal of Ophthalmology
