*2.5. Flow Cytometry*

RASF were primed with TNF (10 ng/mL) (PeproTech, Hamburg, Germany) or left untreated for 72 h in RPMI medium with 2% FCS. Then, cells were analyzed for surface and intracellular expression of cannabinoid receptors. The following antibodies were used: CB1 (FAB3834R, 0.2 mg/mL, 1:10, R&D Systems/Biotechne, Wiesbaden, Germany), CB2 (FAB36551G, 0.2 mg/mL, 1:40, R&D Systems/Biotechne), Isotype MsIgG2a-Alexa 488 (IC003G, 5 μL/test, R&D Systems/Biotechne), and Isotype MsIgG2a-Alexa 647 (IC003R, 5 μL/test, R&D Systems/Biotechne5 μL/test); RASF were detached from culture dishes with citrate buffer (135 mM KCl, 15 mM Na3C6H5O7) and centrifuged at 300× *g*. Cells were resuspended in PBS with 10% FCS and incubated with antibodies for 30 min in the dark at room temperature. For intracellular staining, the inside stain kit was used (#130-090-477, Miltenyi biotec, Bergisch Gladbach, Germany) according to the manufacturer's instructions.

#### *2.6. Isolation of PBMC from Peripheral Blood*

PBMC were isolated using the Greiner LeucoSep Tubes (#227290, Greiner bio-one, Kremsmünster, Austria) according to manufacturer's instructions.

#### *2.7. RASF Co-Culture with PBMC*

Co-culture experiments were performed in 96-well plates (Cellstar, Greiner bio-one, Kremsmünster, Austria). In brief, 5.000 RASF were seeded in 200 μL RPMI-1640 with 10% FCS (Sigma-Aldrich) and grown for 72 h. Then, growth medium was replaced by fresh RPMI with 10% FCS, and 250.000 isolated human PBMCs were added. Cells were stimulated with cytokines/THC as indicated for 7d in RPMI medium with 10% FCS. After that, supernatants were collected and cytokine and immunoglobulin production were assessed by ELISA.

#### *2.8. ELISA and Stimulation of SF*

ELISAs for IL-6 (#555220), IL-10 (#555157) and TNF (#555212) were obtained from BD, Franklin Lakes, NJ, USA and were conducted according to the manufacturer's protocol. Immunoglobulin M (IgM) and G (IgG) were detected by an in-house ELISA. A total of 5.000 RASF were seeded in 200 μL RPMI-1640 with 10% FCS and grown for 72 h. Then, growth medium was replaced by fresh RPMI (2% FCS) and SF were primed with TNF (10 ng/mL) for 3 days to induce TRPA1 protein. After that, culture medium was replaced

with RPMI (2% FCS) and THC was added for an additional 24 h. After that, supernatants were collected and analyzed.

#### *2.9. RASF Cell Viability*

Cell viability was assessed by the cell titer blue viability assay (Promega, Madison, WI, USA, # G8080) according to manufacturer's instructions.
