Lymphocytes, white blood cells of the immune system, circulate throughout the body ready to act in response to an invading toxic agent. Since lymphocytes travel in the bloodstream, the origin of NHL can occur almost anywhere. The classification of NHL has been widely disputed and often controversial. This system bases classification upon morphological features alone. The Working Formulation divides the cells into low, intermediate, and high grade categories.
Low grade refers to tumors with characteristics and functions most like non-tumor cells.
High grade cells are aggressive neoplasms, or tumors, that grow in destructive patterns. Also, the cell surface of cancer cells is usually affected resulting in problems with cell-cell interactions, and displacement of contractile proteins causes poor or decreased adhesion properties to develop. Compared to their stem cells, cancer cells often show altered and stimulated metabolism. Typically, a decrease in aerobic respiration is associated with cancer cells. The cell cycle is also affected in cancerous cells.