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Anti‐αLβ2 antibodies reveal novel endocytotic cross‐modulatory functionality
Author(s) -
Mancuso Riccardo V.,
Casper Jens,
Schmidt Albrecht G.,
Krähenbühl Stephan,
WeitzSchmidt Gabriele
Publication year - 2020
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.14996
Subject(s) - efalizumab , antibody , internalization , monoclonal antibody , receptor , integrin , in vitro , epitope , chemistry , natalizumab , immunology , microbiology and biotechnology , biology , biochemistry , infliximab , tumor necrosis factor alpha , multiple sclerosis
Background and Purpose Antibodies targeting cell surface receptors are considered to enable highly selective therapeutic interventions for immune disorders and cancer. Their biological profiles are found, generally, to represent the net effects of antibody–target interactions. The former therapeutic anti‐integrin αLβ2 antibody efalizumab seems to defeat this paradigm by eliciting, via mechanisms currently unknown, much broader effects than would be predicted based on its target specificity. Experimental Approach To elucidate the mechanisms behind these broad effects, we investigated in primary human lymphocytes in vitro the effects of anti‐αLβ2 antibodies on the expression of αLβ2 as well as unrelated α4 integrins, in comparison to Fab fragments and small‐molecule inhibitors. Key Results We demonstrate that anti‐αLβ2 mAbs directly induce the internalization of α4 integrins. The endocytotic phenomenon is a direct consequence of their antibody nature. It is inhibited when monovalent Fab fragments or small‐molecule inhibitors are used. It is independent of crosslinking via anti‐Fc mAbs and of αLβ2 activation. The cross‐modulatory effect is unidirectional and not observed in a similar fashion with the α4 integrin antibody natalizumab. Conclusion and Implications The present study identifies endocytotic cross‐modulation as a hitherto unknown non‐canonical functionality of anti‐αLβ2 antibodies. This cross‐modulation has the potential to fundamentally alter an antibody's benefit risk profile, as evident with efalizumab. The newly described phenomenon may be of relevance to other therapeutic antibodies targeting cluster‐forming receptors. Thus, pharmacologists should be cognizant of this action when investigating such antibodies.