MOPC315.BM Paraprotein Production Assay

Paraprotein production by MOPC315.BM cells was evaluated by ELISA [23 (link)]. Briefly, 96 well Nunclon ELISA plates were coated with 2 μg/ml of anti-MOPC315.BM paraprotein idiotype (Ab2.1–4) (kindly provided by Prof Bjarne Bogen, University of Oslo, Norway) at 4 °C overnight. Wells were blocked with PBS/0.02% sodium azide/1% BSA, washed and incubated for 2 h at 37 °C with serum samples or standard paraprotein (ranging from 400 to 0.39 ng/ml) diluted in PBS/ 0.02% sodium azide/0.1% BSA/0.1% Tween 20. Then, the plates were incubated with 1 μg/ml biotinylated rat anti-mouse IgA (clone C10–1, BD Pharmingen, Germany) for 1 h at RT, washed, incubated with streptavidin- HRP (1:2000; Sigma-Aldrich) for 1 h at RT and washed again. TMB substrate (Merck Millipore, Billerica, MA, USA) was added for 10-min, the reaction was terminated with H₂O₂ and absorbance measured at 450 nm with a TECAN Infinite M200 ELISA reader.