A case of mistaken identity: The MAR-1 antibody to mouse FcεRIα cross-reacts with FcγRI and FcγRIV

• Published in: Journal of allergy and clinical immunology 2019-04, Vol.143 (4), p.1643-1646.e6
• Main Authors: Tang, Xin-Zi, Jung, James B., Allen, Christopher D.C.
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Monoclonal - immunology; Antibody Specificity - immunology; Cloning; Cross Reactions - immunology; Dendritic cells; Dendritic Cells - immunology; Flow cytometry; Immune response; Immunization; Immunoglobulins; Inflammation; Leukocytes (basophilic); Leukocytes (neutrophilic); Lungs; Macrophages; Mast cells; Mice; Monocytes; Myeloid cells; Neutrophils; Protocol; Receptors, IgE - analysis; Receptors, IgE - immunology; Receptors, IgG - analysis; Receptors, IgG - immunology; Rodents; Software; Staining; Stains & staining; Statistical analysis; Viral infections
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2018.11.045

Because the MAR-1 antibody labeled these cells in the absence of FcεRIα expression, we reasoned it would be more appropriate to call these MAR-1+ moDCs. Because MAR-1+ moDCs have also been reported in mice with viral infection,3 we next tested MAR-1 staining of moDCs in this setting. [...]MAR-1 staining is specific for FcεRIα only on mast cells and basophils, whereas MAR-1 staining on DCs, macrophages, monocytes, and neutrophils is due to FcγR expression. Contrary to prior reports,2-4 our results indicate that the MAR-1+ moDCs observed in mice under inflammatory conditions do not express FcεRI. [...]normal mouse moDCs do not model the FcεRI expression by human DCs in patients with allergic disease. [...]it seems likely that injection of the MAR-1 antibody would cross-link activating FcγRs on these and other myeloid cells, thereby potentially modifying immune responses. [...]we caution investigators in the use of the MAR-1 antibody, and we suggest that in future investigations, FcεRIα KO mice should be used as a critical control.