Background Information

Kappa and Lambda light chain mRNAs

Immunoglobulins are glycoproteins that consist of two polypeptide chains which are called the light and heavy chains respectively. The consistent regions of the heavy chains differ from one class to another, whereas the light chains are the same: either kappa or lambda. The immunoglobulins are expressed on the membrane of B-cells and in the cytoplasm of plasma cells. Before the synthesis of a protein can begin, the corresponding mRNA molecule must be produced and exported to the cell cytoplasm. In normal B-cell populations the ratio of kappa and lambda expressing B-cells is characteristic (2:1) and are randomly distributed with respect to each other. An atypical ratio of kappa-to-lambda expressing cells, or a non-random distribution of these cells, is therefore indicative for a possible neoplasia of the kappa or lambda expressing cells.

The usual method to make a distinction between reactive and neoplastic lymphoid proliferation is to demonstrate monoclonal proliferation. Contrary to immunohistochemistry, in situ hybridization (ISH) analysis avoids the problem of high levels of background staining due to immunoglobulins that are shed in tissue. Several reports have indicated a higher sensitivity for ISH than for immunohistochemistry (e.g. with plasmacytoma, pseudo tumor, multiple myeloma). Moreover, ISH can also show mono- or poly clonality at RNA level whereas immunohistochemistry targets the protein. In those cases where the protein is not transcripted although the RNA is present, ISH will reveal this.

PanPath's REMBRANDT® kit for kappa/lambda is designed for ISH analysis of kappa and lambda light chain mRNAs in tissue sections. The kappa oligonucleotide probe, provided in the kit, is composed of a mixture of 16 oligonucleotides complementary to the constant region of kappa light chain mRNA. The lambda oligonucleotide probe, provided in the kit, is composed of a mixture of 10 oligonucleotides complementary to the constant region of lambda light chain mRNA.