CSF2 and B-cell non-Hodgkin lymphoma: Typically, it is believed that the eosinophilia is caused by the production of various cytokines, such as interleukin (IL)-5, IL-3, and granulocyte–macrophage colony–stimulating factor (GM-CSF) by B cell lymphoma cells or non-neoplastic T lymphocytes activated by B cell lymphoma cells [30,31].