A33-54 Cannabis Smoke Exposure Interferes With Antibody To Mucosal SARS-CoV-2 Vaccination

Background

Cannabinoids present in cannabis smoke are known to have anti-inflammatory effects on both innate and adaptive immune systems. However, it is unclear how these immunosuppressive effects might impact the immune response to vaccination.

Methods

Mice were exposed to room air (control) or cannabis smoke (either THC-high or CBD-high strains) daily then immunized intranasally with a tri-valent formulation of the SARS-CoV-2 (COVID-19) vaccine. After 4 weeks of continued smoke exposure (3 times per week), antigen-specific antibody levels in the circulation and bronchoalveolar lavage fluid (BALF) were measured via titer assay. Following ex vivo stimulation of T cells with SARS-CoV-2 S1 protein, flow cytometry was performed to assess T cell activation and cytokine expression.

Results

Exposure to smoke generated from THC-high or CBD-high cannabis strains led to reductions in SARS-CoV-2 specific antibody levels in the circulation (IgG) and in the BALF (IgG and IgA). Furthermore, serum from cannabis smoke exposed mice exhibited a reduced capacity to neutralize SARS-CoV-2 compared to control serum. Finally, T cell activation following ex vivo stimulation was dampened in THC or CBD smoke-exposed animals, marked by reduced IFNγ and TNFα production.

Conclusion

These considerable disruptions in the humoral response to COVID-19 vaccination suggest that cannabis smoking interferes with adaptive immune competency. This may have a profound impact on the overall efficacy of vaccination in heavy cannabis users, potentially leading to worsened infection outcomes in this population.

This abstract is funded by: CIHR