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Etymology: L, nullus, not one, cella, storeroom
a lymphocyte that develops in the bone marrow and lacks the characteristic surface markers of the B and T cells (surface immunoglobulin or the pan-T antigen). Null cells represent a small proportion of the lymphocyte population. Stimulated by the presence of an antibody, null cells can attack certain cellular targets directly. They kill tumor or viral-infected cells, although not with the specificity of cytotoxic T cells. A null cell is a type of natural killer cell. Compare B cell, T cell. . See also cytotoxin, immune gamma globulin. The term null cell is no longer in common use.
A large lymphocyte without the cell markers of either a T cell or a B cell. Natural killer cells are examples of null cells.
See also: cell
an absence of information, as contrasted with zero or blank or nil, about a value.
called also null lymphocyte; see null cell.
a statistical hypothesis which states that one variable has no association with another variable, or set of variables. That is, the observed results can be explained by chance alone.
see null cell.