Monoclonal Antibodies to Acetylcholine Receptor Secreted by Human X Human Hybridomas Derived from Lymphocytes of a Patient with Myasthenia Gravis

Peripheral blood lymphocytes of a patient with myasthenia gravis (MG) were fused to the non-secreting human lymphoblastoid line HuNSI to produce human x human hybridomas that secrete monoclonal antibodies (mAb) to acetylcholine receptor (AChR). Screening of hybridomas for antibody production involved an enzyme-linked immunosorbent (ELISA) assay with AChR from Torpedo californica (TAChR). 25 of 302 wells tested (8.3%) were positive for anti-AChR antibody production and have been stable in their secretion of mAb for eleven months. Nine lines have been studied in detail. All produced IgM mAb, and most had greater activity against membrane-bound TAChR, than against solubilized TAChR. For anti-AChR clones, the mAb concentration in culture supernatants ranged from 2 to 33 ug/ml. Saturation curves of binding to TAChR performed on 4 lines demonstrated dissociation constants (Kds) estimated to range from 0.1-1.0 nM. The patient whose lymphocytes were used in this study had a serum anti-AChR antibody concentration of 243nM against human AChR and 15nM against AChR from T. californica. The results demonstrate the feasibility of producing stable human x human hybridomas secreting mAb to the autoantigen from the peripheral blood of patients with organ-specific autoimmune diseases. The mAb produced here may prove to be useful in analyzing, and possibly treating, the autoimmune phenomena in MG.