Dulbecco modified essential medium

TE671 is a rhabdomyosarcoma cell line with muscle‐like properties (Stratton et al. 1989). CN21 cells derive from the TE671 cell line and have been stably transfected with the cDNA of the human AChR ε‐subunit, such that the adult AChR isoform is expressed in high numbers with only a remaining small fraction of fetal AChRs (Beeson et al. 1996). TE671 and CN21 were cultured at 37°C and 5% CO₂ in Dulbecco‐modified essential medium (DMEM) (Sigma‐Aldrich, St Louis, MO, USA) supplemented with 10% fetal calf serum (FCS) and 1% antibiotics/anti‐mycotics [i.e. penicillin G, streptomycin and amphotericin B (PSA)] (Invitrogen, Carlsbad, CA, USA). HEK293 cells were maintained at 37°C and 5% CO₂ in DMEM supplemented with 10% FCS and 1% PSA. C2C12 were maintained at 37°C and 5% CO₂ in DMEM supplemented with 15% fetal calf serum and 1% antibiotics/anti‐mycotics and differentiated to form myotubes for 4–7 days in DMEM supplemented with 2% fetal calf serum and 1% antibiotics/anti‐mycotics.

Penicillin‐streptomycin, L‐glutamine, DMEM plus GlutaMAX, and minimum essential medium (MEM) non‐essential amino acids were from Invitrogen (Stockholm, Sweden), whereas Dulbecco Modified Essential Medium (DMEM), all salts for buffers, and the anti‐DNP IgE antibody were from Sigma (Stockholm, Sweden). DNP‐HSA was from Biosearch Technologies (Petaluma, CA). BET protein inhibitors PFI‐1 (PF‐6405761), I‐BET151 (GSK1210151A), and I‐BET762 (GSK525762) were from Sigma.

TE671 cells express only the fetal AChR isoform and were used to test the AMC plasmas. CN21 cells derive from the TE671 cell line that was stably transfected with excess cDNA encoding the human AChR ε-subunit, so that the adult AChR isoform is the predominant form expressed.14 (link) Both cell lines were cultured at 37°C and 5% CO₂ in Dulbecco-modified essential medium(DMEM; Sigma-Aldrich) supplemented with 10% fetal calf serum and 1% antibiotics/antimycotics (ie, penicillin G, streptomycin and amphotericin B, PSA) (Invitrogen).