Immunoprecipitation is a technique in which an antigen is isolated by binding to a specific antibody attached to a sedimentable matrix. It is also used to analyze protein fractions separated by other techniques such as gel filtration or density gradient sedimentation. The source of antigen for immunoprecipitation can be unlabeled cells or tissues, metabolically or intrinsically labeled cells, or in vitro-translated proteins. This unit describes a wide range of immunoprecipitation techniques, using either suspension or adherent cells lysed by various means.Usually, plasmas transfected cells or natural cells are ideal sample for immunoprecipitation.
Raji cell line is the first continuous human cell line from hematopoietic origin. The cell line produce an unusual strain of Epstein-Barr virus and it will both transform cord blood lymphocytes and induce early antigens in Raji cells. Translocations between chromosomes 8 and 22 have occurred in all three lines, but the cells synthesize immunoglobulin M with light chains of the kappa type, in contrast to the usual concordance between a translocation involving chromosome 22 and lambda chain synthesis. Both kappa genes and one lambda gene are rearranged. These findings indicate that translocation may occur as a separate event from immunoglobulin gene rearrangement or indicate that the proposed hierarchical sequence of immunoglobulin gene rearrangements is not always adhered to. The datas also imply that in cells containing a translocation between the long arm of chromosome 8 and a chromosome bearing an immunoglobulin gene, alteration of cellular myc expression may occur regardless of the immunoglobulin gene that is expressed. Raji cell is widely used as a transfection host and also to understand the hematopoietic and other cell malignancies. It also use for detection of immune complex which possesses and expresses lots of receptors for certain complement components, as well as Fc receptors for immunoglobulin G.