Feline immunoglobulin E: induction of antigen-specific antibody in normal cats and levels in spontaneously allergic cats

Sera from 10 cats with symptoms consistent with atopy, from 15 normal household cats and from 11 laboratory maintained cats were assessed for allergen-specific IgE and IgG to Dermatophagoides farinae (DF) by enzyme-linked immunosorbent assay (ELISA). In addition, 10 normal cats were immunised with DF and intradermal skin tests (IDST) were performed weekly. Sera from the latter were also assessed for DF-specific IgE by ELISA and using Prausnitz–Küstner (PK) tests. Although DF-specific IgE was detectable in all the atopic cats, there was no significant difference between the levels in this group and in the clinically normal household cats. However levels in both these groups were significantly higher than those in the laboratory maintained cats. Detectable DF-specific IgE was induced in all of the 10 cats, but the levels were not correlated with the development of positive IDSTs, nor with the level of IgE as assessed by PK tests. These findings are consistent with a possible heterogeneity of IgE antibody in cats.