Each immunoglobulin molecule consists of two identical heavy chains and two identical light chains. There are two types of light chains designated as kappa and lambda. The kappa light chain antibody labels kappa light chain expressing B lymphocytes and plasma cells. Other cells may also express kappa light chain due to nonspecific uptake of immunoglobulin. Anti-Kappa recognizes surface immunoglobulin on normal and neoplastic B-cells, and has been indicated as a potential aid in the identification of leukemias, plasmacytomas, and certain non-Hodgkin's lymphomas, where the expression of a single light chain class is restricted. The determination of light chain ratio is critical in evaluating B-cell neoplasms, as the majority of B-cell lymphomas express either kappa or lambda light chains, while a mixture of kappa and lambda is characteristic of reactive proliferations. In paraffin-embedded tissue, Anti-Kappa displays strong staining of kappa-positive plasma cells, as well as cells that have absorbed exogenous immunoglobulins.