Lambda light chains are polypeptide chains located in the cell membrane and cytoplasmic regions of normal B cells and plasma cells. The combination of lambda light chains and heavy chains forms immunoglobulin molecules. There are two classes of light chains found in immunoglobulins, kappa light chains and lambda light chains. Light chain production by lymphoid cells is genetically restricted such that the immunoglobulin molecules produced by an individual cell will only contain a single light chain class. This clonal restriction may be used to indicate the polyclonal or monoclonal nature of B cell and plasma cell populations. The ratio of Kappa to Lambda is about 2:1. The level of kappa or lambda can be greatly elevated in multiple myeloma or other B cell malignancies.