Validating Antibodies to the Cannabinoid CB2 Receptor

The problem of antibody reliability in research has now reached the point where many journals reject any work that lacks adequate controls for antibody validation. Despite this, it is still common for researchers to rely on positive controls and only minimal negative controls (such as blocking peptide controls). Using careful cross-comparisons between antibody labeling and other labeling techniques (such as autoradiography or in situ hybridization) it is possible to criticize and even validate antibodies using this approach; for example, that performed for the cannabinoid CB1 receptor in the analysis carried out by Grimsey and colleagues (Grimsey et al. 2008). However, the fundamental distinction between antibody sensitivity and specificity, corresponding to positive and negative controls, respectively, remains insufficiently appreciated. In this study, we developed a very strong positive control for immunoblot labeling of the cannabinoid CB2 receptor. Our work shows clearly that an antibody may pass stringent positive controls, but still fail specificity tests using strong negative controls. Antibodies for G protein-coupled receptors (GPCRs), of which the cannabinoid CB2 receptor is a member, have been particularly challenging (Ashton 2011; Baek et al. 530995 JHCXXX10.1369/0022155414530995Marchalant et al.Sensitivity, Specificity and the CB2 Receptor research-article2014