Objectives The relationship between exposure to
rodent allergens and laboratory animal allergy is
complex; at highest allergen exposures there is an
attenuation of sensitisation and symptoms which are
associated with increased levels of rat-specific
immunoglobulin (Ig)G and IgG4 antibodies. We set out
to examine whether the increased levels of rat-specific
IgG and IgG4 antibodies that we have previously
observed at high allergen exposure in our cohort of
laboratory animal workers play a functional role through
blockage of the binding of IgE–allergen complex binding
to CD23 receptors on B cells.
Methods Cross-sectional survey of laboratory animal
workers (n=776) in six UK pharmaceutical companies
were surveyed. IgE–allergen complex binding to B cells
was measured in 703 (97.9%) eligible employees; their
exposure was categorised by either job group or number
of rats handled daily.
Results We observed a significant decrease in
IgE–allergen complex binding to B cells with increasing
quartiles of both rat-specific IgG and IgG4 antibodies
(p<0.001). IgE–allergen complex binding to B cells was
lower in workers with high allergen exposure, and
significantly so (p=0.033) in the subgroup with highest
exposures but no work-related chest symptoms.
Conclusions These findings demonstrate a functional
role for rat-specific IgG/G4 antibodies in laboratory
animal workers, similar to that observed in patients
treated with high dose immunotherapy who become
clinically tolerant, suggesting a potential explanation for
the attenuation of risk at highest allergen exposures.