Malignant Lymphomas Other than Hodgkin’s Disease

Publisher Summary This chapter discusses membrane and cytoplasmic changes in B lymphocytes induced by ligand–surface immunoglobulin (Ig) interaction. Surface Ig is the receptor for antigen molecules on B lymphocytes. Surface Ig has been identified on the B-cell surface by using immunocytochemistry or direct biochemical analysis. The number of Ig molecules presumably serving as antigen receptors on the B cell surface is on the average of 105 molecules per B cell. The amount of surface-bound Ig is large comparing to the number of hormone receptors needed to trigger certain cellular responses. One could speculate that many of the surface Ig–antigen interactions result in nonfunctional events; therefore, many receptors are needed. The B cell requires such a high number of receptors to effectively bind antigen molecules of large size and variable epitope densities or a number of successive hits are needed in these cells to reach an effective threshold of stimulation. The distribution of surface Ig and other surface macromolecules has been studied at the ultrastructural level by using various methods. One method was the ultrastructural analysis of regular thin section of cells exposed to antibodies conjugated to a large visible molecule.

Membrane and Cytoplasmic Changes in B Lymphocytes Induced by Ligand-Surface Immunoglobulin Interaction

http://science.sciencemag.org/content/sci/189/4207/964.full.pdf

Immunoglobulin-receptors revisited.

Human tissues involved with lymphoma have been examined in frozen sections for immunoglobulin-bearing cells by a technique involving double-label immunofluorescence with mixed anti-kappa and anti-lambda antibodies. F (ab')2 fragments of purified antibodies were employed to avoid any binding via Fc receptors. B cell lymphomas were shown to be composed of monoclonal populations of Ig bearing cells, whereas normal or reactive lymphoid follicles contained a mosaic of Ig-bearing cells derived from multiple clones. Nodules of lymphoma were often surrounded by normal polyclonal B cell populations. We anticipates that the approach described here will be useful in the diagnosis of lymphoma, differentiating it from reactive lymphoid hyperplasia by the demostration of monoclonality. In addition, it should provide a sensitive and reliable tool for investigating the immunobiology of human lymphoma.

https://rupress.org/jem/article-pdf/145/4/1014/1088409/1014.pdf

The monoclonality of human B-cell lymphomas.

Publisher Summary Immunoglobulin A (IgA) is the principal class of immunoglobulin in most external secretions It is made by plasma cells in glands and mucous membranes that face the external environment The secretory form of IgA, known as secretory IgA, has distinctive antigenic and structural characteristics due to the presence of an extra polypeptide chain, the secretory component This chapter emphasizes the maturation of IgA during ontogeny; synthesis and assembly of IgA; IgA cell cycle; thymus dependency of IgA; and disorders of IgA production The chapter discusses the functions of IgA antibodies Commitment of an immunocyte to the production of IgA is the terminal step in a differentiation process that begins with a cell bearing IgM on its surface On balance, the evidence favors a direct switch from IgM to IgA Much of the IgA secreted by the plasma cells in exocrine glands and mucous membranes is dimeric The fully assembled secretory IgA molecule is the synthetic product of two distinct types of cell, both of which reside locally in the mucous membrane or gland As is the case with IgG and IgE, the secretion of IgA is thymus dependent In humans, thymic dysfunction is often associated with diminished IgA The chapter also presents many interesting and important problems related to IgA that remain to be solved

Cellular Aspects of Immunoglobulin A

A large proportion of the human peripheral blood lymphocytes of adults and newborns having IgD were found also to have IgM on their membranes and vice versa. A few lymphocytes had one of these classes only. IgD and IgM could be capped independently on the same cell. The possibility that IgD was acquired by a cytophilic process was excluded by the finding that IgD-bearing cells were of one light chain type only, and by the direct demonstration of reappearance of IgD on the lymphocyte membrane during incubation in an IgD-free culture medium. On the basis of these findings, it is proposed that IgD functions as a lymphocyte antigen receptor.

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Katharina Hug

Papers

Immunoglobulin d as a lymphocyte receptor