The significance of circulating IgE. Correlation of amount of circulating reaginic antibody with cutaneous sensitivity in the rat.

In order to determine the relationship between the level of circulating reaginic (IgE) antibody and degree of cutaneous hypersensitivity, rats producing different titres of reaginic antibody were assessed for skin test reactivity by means of the active cutaneous anaphylaxis test. Skin reaction diameters of ovalbumin-sensitive rats were similar whether they were producing low or markedly elevated levels of ovalbumin reagins. In rats infected with Nippostrongylus brasiliensis, skin test reactivity to N. brasiliensis antigen was demonstrable before reagin became detectable in the circulation. It increased to maximum shortly after the appearance of circulating reagin, and thereafter showed no significant increase commensurate with the further rise in reagin titre. The results show that in the rat there is no direct quantitative relationship between the size of skin test reactions and the level of specific circulating reaginic antibody.