Cross reactivity between rat and mouse urinary allergens

Abstract

Rationale Laboratory animal workers who are sensitized to rats are highly likely also to be sensitized to mice. In a recent study of 100 individuals with specific IgE to rat urine, 62% were also IgE positive to mouse urine. Conversely 95% of mouse-sensitized individuals were also rat sensitized. Rat and mouse urinary proteins both belong to the lipocalin group of proteins and share 66% sequence homology. It is likely that rat and mouse urinary allergens share common B cell epitopes. We have therefore investigated the degree of cross reactivity between rat and mouse urinary allergens. Methods Six individuals with a RAST binding to rat and mouse of greater than 10% were selected for RAST inhibition experiments. Individual sera were incubated overnight with 1mg, 0.1mg, 0.01mg or 0.001mg rat and mouse urine. RAST to rat and mouse urinary protein were carried out the following day using the inhibited sera. Results All individuals exhibited very different inhibition profiles, irrespective of their specific IgE levels to rat and mouse urinary allergens. In general rat urine inhibited the binding of IgE to mouse urine (55-95% inhibition) more strongly than mouse urine was capable of inhibiting specific IgE to rat urine (30–80% inhibition). There was almost complete inhibition with homologous urinary protein. Conclusions These finding confirm immunologically that rat and mouse urinary allergens have common and some unique B cell epitopes which result in varying inhibitions profiles.