Raji cell

Raji cell culture.

Raji cell line is the first continuous human cell line from hematopoietic origin.^[1] The cell lines produce an unusual strain of Epstein-Barr virus which 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 either that translocation may occur as a separate event from immunoglobulin gene rearrangement or that the proposed hierarchical sequence of immunoglobulin gene rearrangements is not always adhered to. The data 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.^[2] Raji cell is widely used as a transfection host and also to understand the hematopoietic and other cell malignancies. It also used for detection of immune complex because it possesses and expresses several receptors for certain complement components, as well as Fc receptors for immunoglobulin G.^[3]

Background

Based on the morphological characteristic, this cell is categorized as lymphoblast-like.^[4] This suspension cell is derived from B-lymphocyte of an 11-year-old Nigerian Burkitt's lymphoma male patient in 1963. R.J.V. Pulvertaft is the first person who established this cell line.^[4] The culture medium used to grow this cell line is RPMI supplemented with serum. Some characteristics of Raji cell is lack of differentiation thus shows the formation of large aggregations consist of hundreds individual cells. The cells are relatively large in diameter (5-8 μm), have irregular indented nuclei, and almost extensive cytoplasm with free ribosomes which tend to clump.^[5] Raji cell grows as single, non-motile, free-floating (non-adhesion) individuals or doublets to glass. Some cells look elongated like pear-shaped with larger, multinucleate, round cells.^[5]

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 because it possesses and expresses and lots of receptors for certain complement components, as well as Fc receptors for immunoglobulin G.^[3]

Description

A cell of a cultured line of lymphoblastoid cells derived from a Burkitt lymphoma; it possesses numerous receptors for a certain complement components and is thus suitable for use in detection of immune complexes. It expresses certain complement receptors as well as Fc receptors for immunoglobulin G.^[6]

Raji Cell Line Human

-Biological source --> Lymph from human

-Description --> Human Black, Burkitt's lymphoma

-Growth Mode --> Suspension

-Karotype --> 2n=46, diploid

-Morphology --> Lymphoblastoid

-Research Areas --> Kits/ Lysates/ Other -> Lysates -> Whole Cell Lysates -> Human^[7]

-Shipped In --> Dry ice

-Storage Temperature --> -196 degrees C.^[8] Raji cell slide can be stored for up to 6 months at 4 °C under desiccate conditions.

Raji Cell Binding Test

A test for the detection of soluble immunoglobulin (Ig)G-antigen complexes. Raji cells are a line EBV-transformed lymphocytes with surface Fc receptors. Complexes are detected by their ability to compete with a radiolabelled aggregated IgG for binding to cells.

Raji Cell Assay for Immune Complexes

Using a standard Raji assay employing 125I-IgG goat anti-human Fc gamma, the digestion of Raji cells with pronase reduced by 95% their ability to bind complement-fixed aggregated human gamma globulin and complement-fixed tetanus toxoid-antitetanus toxin complexes. However, binding at 37 degrees C of IgG from the sera of 16 patients with systemic lupus erythematosus (SLE) to pronase-digested Raji cells was reduced much less consistently and extensively (9-100% reduction; mean reduction of 51%). In more detailed studies of two SLE sera, sucrose density gradient centrifugation showed that greater than 50% of the IgG binding to undigested Raji cells sedimented in the 7S region. Pepsin digestion of immunoglobulin fractions from four SLE sera caused a reduction in SLE IgG binding to undigested Raji cells when detected with 125I anti-Fc gamma, but an increase when binding was detected with 125I-anti-Fab, suggesting that substantial SLE IgG can bind through F(ab')2 regions. Binding of IgG from SLE sera was not directed at neoantigenic sites induced by pronase digestion because binding activity was adsorbed with undigested cells as readily as with digested cells. Moreover, sera from 10 SLE patients that had negative Raji assays contained no IgG that bound to pronase-digested Raji cells. Meaning that, much of the IgG bound at 37 degrees C to Raji cells from the sera of many patients with SLE does not represent immune complexes but is probably antibody directed toward sites on the Raji cell.^[9]

Raji cell Radio-immune Assay for Detecting Immune Complexes in Human Sera

A sensitivie and simple procedure for the detection and quantitation of soluble complement (C)- fixing immune complexes in sera of patients with various disease states has been developed by utilizing C receptors on Raji cells. These cells lack membrane-bound immunoglobulin but have receptors for IgG Fc, C3b, C3d, and possibly with other C proteins. Uptake experiments showed that both aggregated human gamma globulin (AHG) and 7S IgG bound to receptors for IgG Fc; however, AHG reacted with C bound to cells only via receptors for C and this binding was much more efficient than via IgG Fc receptors. AHG was used as an in vitro model of human immune complexes and its uptake by Raji cells was quantitated by 125I-radiolabeled antihuman IgG. The limit of sensitivity of this test was 6 mug AHG/ml serum. The ability of Raji cells to detect AHG in serum depended on the amount of radioactive antibody used and the size of aggregates. The presence of an excess of C somewhat inhibited binding of AHG containing C to Raji cells. The efficient binding of AHG by receptors for C on Raji cells was used for the detection and quantitation of immune complexes in human sera. Raji cells were incubated with sera to be tested and then reacted with excess radiolabeled antihuman IgG; the amount of radioactivity bound to the washed cells was determined and referred to a standard curve of radioactive antibody uptake by cells previously incubated with increasing amounts of AHG in serum. Thereby immune complexes were detected and quantitated in serum hepatitis, systemic lupus erythematosus, vasculitis, subacute sclerosing panencephalitis, dengue hemorrhagic fever, and malignancies.^[10]

References

External links

• Cellosaurus entry for Raji