Immunologically competent B lymphocytes develop from a lymphoid stem cell until acquiring a receptor consisting of a single immunoglobulin molecule specific for a determined antigen. These immunoglobulin molecules are formed by two identical heavy chains and by two identical light chains (kappa or lambda).
In humans, in normal or reactive lymphoid tissues, approximately 60% of the B lymphocytes bear kappa light chains and the remaining 40%, lambda light chains. In B lymphocyte tumors, there is generally only one clone that proliferates, be it kappa or lambda, in a monoclonal way.
In humans the gene that codes for kappa light chains is located on chromosome 2,
and the gene that codes for lambda light chains is located on chromosome 22. The variable regions for genetic recombination are located in the first 5' half of these genes, while the constant regions are located in the 3' half. There is only one functional gene for the constant region of k light region, and
four functional genes for the constant region
of l light chains (Cl1, Cl2, Cl3, and Cl7). Detection of monoclonality is one of the most important tools for differentiating B lymphoid tumors from reactive processes. In situ hybridization technique offers an important advantage over immunohistochemistry, as it virtually lacks background, and allows a clean and sharp viewing of the histological preparation. It is also useful to differentiate cells that have absorbed
immunoglobulins, and are therefore detectable by immunohistochemistry, but in fact do not produce immunoglobulin, as occurs with the Reed-Sternberg cells of Hodgkin's disease.
Intended for research use only (RUO).