Marijuana has numerous roles as an agonist in the endocannabinoid signaling system (ESS). This study evaluated monoclonal antibodies across experimental techniques to establish a framework for studying ESS receptors, CB1 and CB2.

Tissue from five patients with head and neck cancer were used to generate cell lines and formalin-fixed paraffin-embedded (FFPE) sections, which were analyzed by western blot (WB), immunohistochemistry (IHC), and immunofluorescence (IF). Subgroup analysis was performed on FFPE sections from 8 marijuana users and 10 controls by IHC. Results were compared across methods for consistency.

In all patients, WB and IF were CB1 positive, whereas IHC was negative. Select samples were CB2 positive by WB, but failed IF and IHC applications. In subgroup analysis, 1 of 8 users and 3 of 10 nonusers were CB1 positive.

Interpretation of CB1/CB2 antibody data should be performed cautiously and confirmation of findings across multiple experimental methods is recommended.