Info
origin_of_mature_b_cell_lymphomas
B cell lymphomas are cancers that develop from the malignant transformation of B lymphocytes at various stages of ontogeny. Most are of mature B cell origin, and revolve around the germinal centre (GC) reaction, a critical step in which B cells are subject to intense proliferation and genomic remodelling processes — namely, somatic hypermutation and class-switch recombination — to generate memory B cells and plasma B cells that produce high-affinity antibodies. From naive B cells to memory B cells, most differentiation steps are associated with a malignant B cell subtype (defined as the cell of origin (COUP)) on the basis of classic histological definitions and gene expression profiling. The COUP assumes that B cell malignancies are ‘frozen’ at a given B cell differentiation stage arising in a particular location of the B cell follicle. For example, follicular lymphoma (FL) is a follicle-related B cell lymphoma that is considered the malignant counterpart of normal ‘frozen’ GC B cells. Unmutated mantle cell lymphoma (UM-MCL) originates from mantle zone B cells, marginal zone lymphoma (MZL) resembles marginal zone B cells whereas Burkitt lymphoma (BL) resembles dark zone B cells. Based on the COUP, distinct diffuse large B cell lymphoma (DLBCL) molecular subtypes are defined as not otherwise specified DLBCL (DLBCL NOS), whereas, the GC B cell-like DLBCL corresponds to B cells that are arrested at various stages of the GC transit (from dark zone to light zone B cells) and the activated B cell-like DLBCL seems to derive from GC B cells en route to plasma cell differentiation, resembling plasmablasts. BCR, B cell receptor; FDC, follicular dendritic cell; M-MCL, mutated mantle cell lymphoma; MHC, major histocompatibility complex; TCR, T cell receptor; TFH, follicular T helper. Adapted from reF.44, Springer Nature Limited.
