Immunoglobulin Light Chain - in Pathology

In Pathology

B-cells in lymphoid tissue possess either kappa or lambda light chains, but never both together. Using immunohistochemistry, it is possible to determine the relative abundance of B-cells expressing kappa and lambda light chains. If the lymph node or similar tissue is reactive, or otherwise benign, it should possess a mixture of kappa positive and lambda positive cells. If, however, one type of light chain is significantly more common than the other, the cells are likely all derived from a small clonal population, which may indicate a malignant condition, such as B-cell lymphoma.

Ig light chains produced in neoplastic plasma cells, such as in multiple myeloma, are called Bence Jones proteins.

Increased levels of free Ig light chains have also been detected in various inflammatory diseases. It is important to note that, in contrast to increased levels in lymphoma patients, these Ig light chains are polyclonal. Recent studies have shown that these Ig light chains can bind to mast cells and, using their ability to bind antigen, facilitate activation of these mast cells (Redegeld (2002)). Activation of mast cells results in the release of various pro-inflammatory mediators which are believed to contribute to the development of the inflammatory disease. Very recent studies have shown that Ig light chains not only activate mast cells but also dorsal root ganglia (Rijnierse, 2009)) and neutrophils (Braber and Thio (2012)), expanding their possible role as mediators in inflammatory disease.