Blocking of Histamine Release and IgE Binding to FcεRI on Human Basophils by Antibodies Produced in Camels

PURPOSE The production of camel heavy-chain antihuman IgE (huIgE) that has the potential to block IgE-FcεRI interaction and histamine release by basophils. METHODS Camels were immunized with a synthetic loop peptide (SLP) designed in a multiple antigen peptide system (MAPS) forming SLP-MAPS immunogen. Camel polyclonal antibodies (PCAs) were produced, purified, characterized using Protein A & G, ELISA, and SDS-PAGE, and tested for their potency to block passive sensitization and histamine release of human basophils using flow cytometry (FCM) and ELISA, respectively. RESULTS FCM data indicated that camel conventional (IgG1) and heavy chain antibodies (HCAbs; IgG2, and IgG3) had blocking activities of 43.9%, 72%, and 96.6%, respectively. Moreover, both IgG2 and IgG3 achieved remarkable inhibition rates of 93.98% and 97.05% in histamine release, respectively, whereas the IgG1inhibiting activity was 60.05%. CONCLUSIONS Camel PCAs produced against SLP-MAPS were capable of blocking the IgE-receptor interaction and the release of histamine by basophils with superiority to HCAbs. These findings may pave the way toward the possible use of camel anti-huIgE HCAbs as blocking antibodies in the treatment of IgE-mediated allergy and asthma.