Rat monoclonal anti-murine IgE antibody removes IgE molecules already bound to mast cells or basophilic leukemia cells, resulting in the inhibition of systemic anaphylaxis and passive cutaneous anaphylaxis.

IgE plays a central role in allergic reactions. Some anti-IgE antibodies (HMK-12, 6HD5) inhibit the binding of IgE to the FcepsilonRI of mast cells/basophilic leukemia cells (PT-18, RBL/2H3), but less inhibition is seen with the anti-allotypic JKS-6 and the anti-idiotypic Eb-1. Anti-IgE HMK-12 can detach bound IgE molecules from the FcepsilonRI. When mast cells or basophils were incubated with monoclonal anti-DNP-IgE SPE-7, washed and treated with anti-IgE HMK-12, anti-IgE/IgE complexes were found in the supernatant. Similar results were obtained with the Fab fragment of HMK-12. Mice injected with anti-DNP-IgE SPE-7 and later with DNP-BSA had the typical systemic anaphylactic shock. However, if they were injected with the anti-IgE antibody (HMK-12) before the challenge, they did not get an anaphylactic shock. In the sera of mice injected with monoclonal IgE SPE-7 and anti-IgE antibody (HMK-12), IgE/anti-IgE complexes were detected. No passive cutaneous anaphylaxis occurred if the rats were injected with anti-IgE antibodies before the challenge. In summary, anti-IgE antibodies can remove IgE antibodies from the FcepsilonRI; anti-IgE/IgE complexes can be detected in vitro and in vivo, and anti-IgE antibodies can inhibit IgE-mediated systemic or local anaphylactic reactions.