Practice question

Hybridoma formation relies on merging two complementary cellular programs within one cytoplasm to create self-renewing antibody factory. Splenic B lymphocytes from immunized donor possess productively rearranged heavy chain locus on chromosome 14 with VDJ recombination mediated by RAG1/2 and light chain kappa or lambda locus with VJ recombination, encoding high-affinity combining site selected through germinal center affinity maturation involving activation-induced deaminase, but they senesce within days after extraction due to lack of telomerase, dependence on BAFF survival signal, and activation of mitochondrial apoptosis. Myeloma cells are malignant plasma cell tumors adapted to suspension culture, thriving in RPMI-1640 with 10 percent serum, exhibiting constitutively active PI3K-AKT, NF-kB, and c-Myc driving endless cell cycle progression bypassing G1/S checkpoint. When mixed at optimized ratio of one myeloma to five B cells and exposed to 50 percent polyethylene glycol 1450, plasma membranes dehydrate, outer leaflets merge forming hemifusion stalk, expansion creates fusion pore allowing cytoplasm mixing, endoplasmic reticula intermix, binucleated heterokaryons undergo mitosis to become mononucleated hybrids retaining immunoglobulin genes from B partner and proliferative machinery from tumor, describing core fusion of antibody-producing B cell and myeloma cell.