Secreted immunoglobulin

So-called, B lymphocytes, which constitute about 20% of the total lymphocyte population in the blood, have only one major function which is to synthesize and secrete immunoglobulin antibodies. Following an antigenic challenge, B cells develop into plasma cells whose role is to produce specific immunoglobulin molecules in what is known as the humoral arm of the immune response. 

Rat plasmacytomas are available, derived from the ileocecal lymph nodes of the LOU/C strain. The first rat-rat hybridoma was described by Galfre and coworkers in 1979 using the aminopterin sensitive line R210Y3.Agl.2.3 (Y3), which secretes immunoglobulin light chains. Further nonproducing rat myelomas YB2/0 and IR983F have since been derived. 

McCune, J.M., Lingappa, V.R., Fu, S.M., Blobel, G., Kunkel, H.G. (1980). Membrane-bound and secreted immunoglobulins. I. Two distinct translation products of human p-chain, with identical N-termini and different C-termini. J. Exp. Med. 152,463-468. 

Melcher, U. Uhr, J.W. (1977). Density differences between membrane and secreted immunoglobulins of murine splenocytes. Biochemistry 16, 145-152. 

The argument has been made that the first steps of class switching in cells not yet secreting immunoglobulin involve the differential splicing of long transcripts span-... 

Many different types of proteins are glycoproteins. For example, stractural proteins such as collagen, proteins found in mucous secretions, immunoglobulins, folhcle-stimu-lating hormone and thyroid-stimulating hormone, interferon (an antiviral protein), and blood plasma proteins are all glycoproteins. One of the functions of the polysaccharide chain is to act as a receptor site on the cell surface in order to transmit signals from hormones and other molecules across the cell membrane into the cell. The carbohydrates on the surfaces of cells also serve as points of attachment for other cells, vimses, and toxins. 

B cells Form plasma cells that secrete immunoglobulins (IgG, IgA, and IgE) Participate in antigen-antibody complex-mediated tissue damage (type III hypersensitivity)... 

There is some evidence to support the thesis that the soluble and membrane-bound immunoglobulins may have sequence or other structural differences. Studies have shown SIg and secreted immunoglobulins are synthesized at different rates and that SIg turnover occurs at a slower rate (Choi, 1976). These findings have been interpreted to indicate that... 

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