Practice question

Primary B lymphocytes after differentiation short-lived plasma cells produce Ig extraordinary rate but survive 3-5 days culture due activation-induced death mediated Fas upregulation after strong BCR crosslinking and lack telomere maintenance somatic cells lacking telomerase entering senescence limited divisions dependence extrinsic survival signals CD40L helper T cells cytokines IL-4 IL-6 IL-21 follicular helper. Continuous monoclonal manufacturing over months requires immortalization essential. Myeloma plasmacytoma malignant transformation plasma cells proliferate indefinitely without exogenous growth factors due translocation placing oncogene c-myc under IgH enhancer driving cyclin D and constitutive IL-6 secretion creating autocrine loop activating JAK-STAT pathway promoting survival proliferation. Fusion with B cell transfers transformation phenotype granting hybridoma sustained division >100 passages cryopreservation stability preserving viability liquid nitrogen storage ability grow serum-free chemically defined bioreactors scaled 2000 L robust ER comprising chaperone BiP protein disulfide isomerase folding heavy light chains efficiently. While antibody specificity derives entirely B-cell partner rearranged Ig loci longevity continuous secretion originate myeloma component overcoming natural mortality limitation enabling long-term production and banking hybridoma lines.