Lymphomas arise from malignant clones of lymphocytes. Lymphocytes are a normal part of the peripheral blood population of circulating white cells and normally serve the functions of immune protection and inflammatory responses to foreign (or self) antigens. They are derived from progenitor cells in the bone marrow and the lymph nodes.
Lymphocytes are classified into B and T cells. Originally this classification was because the T cells derived from a Thymic origin, whereas the B cells came from an origin in the gut mesentery, which in the chicken was termed the Bursa of Fabricious.
The two groups of lymphocytes normally sub-serve different lymphocyte functions.
Lymphomas are classified into those arising from B or T lymphocytes but this is only part of a very complex classification system.
Nowadays the origins of the cells and the identification of different subsets of lymphoma has become much more complicated and the consequence is that the term non-Hodgkin lymphoma encompasses a very large and heterogenous spectrum of diseases, many of which are not described here in detail.