Adhesion of human B cells to germinal centers in vitro involves VLA-4 and INCAM-110

Article Abstract:

The lymph nodes each contain a special region called the germinal center, where B cells (the white blood cell type that mediates the humoral immune response) proliferate and acquire the specific characteristics they need to fight foreign proteins (antigens). However, the means are not known by which B cells leave the circulation and move through the gland to their ultimate resting place in the germinal center. Several experiments were carried out to address this issue. B cells that had been activated by exposure to bacteria showed a preference for binding to the germinal centers of lymphoid tissue in frozen sections, whereas unstimulated B cells showed no such preference. Thus, it appears that the surface proteins (antigens) of B cells change after the cell is activated, influencing its binding capabilities. Other experiments showed that B cells, in all likelihood, do not adhere to high endothelial cells (which line the smallest venules in lymph nodes, allowing white blood cells to pass through), as was thought. Rather, it appears that two molecules, VLA-4 and INCAM-110, located on B cells and follicular dendritic cells (a cell type in the lymph node), respectively, interact to guide B cell migration through the node. VLA-4, in itself, will not guarantee binding, but it is possible that the activated B cell expresses a somewhat different form of that molecule. (Consumer Summary produced by Reliance Medical Information, Inc.)

B cells, Molecular biology, Cell adhesion, Lymphoid tissue

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An inducible endothelial cell surface glycoprotein mediates melanoma adhesion

Article Abstract:

Metastasis, or the spread of cancer cells through the blood stream, is an inefficient process. It appears that the lining of blood vessels may act as a barrier to the tumor cells. However, when the endothelium, the tissue lining the blood vessels, becomes activated by cytokines (factors that are secreted by various cells), tumor cells such as melanoma and carcinoma cells bind to it more readily. Monoclonal antibodies have been developed against the proteins present on cytokine-stimulated human endothelial cells. These antibodies, which blocked binding of tumor cells to endothelial cells, were used to identify the molecules involved in binding. The proteins were biochemically characterized. A protein known as inducible cell adhesion molecule 110 (INCAM-110) on endothelial cells was induced by cytokines and appears to mediate adhesion of melanoma cells. Another protein, endothelial lymphocyte adhesion molecule 1 (ELAM-1), also on endothelial cells, is involved in the binding of colon cancer cells. The identification of proteins that bind tumor cells to the endothelium cells of blood vessels and the subsequent development of monoclonal antibodies that block the binding may lead to reagents that could be used therapeutically to inhibit the spread of cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)

Methods, Metastasis, Cancer invasiveness, Cancer metastasis, Cell receptors, Melanoma, Protein research, Vascular endothelium

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Variability among human umbilical vein endothelial cultures

Article Abstract:

Human umbilical vein endothelial cells cultured under standard conditions of median and growth factors did not respond to human interleukin-8 as a mitogen, but cells cultured under variant conditions of media and growth factors did.

Culture media (Biology), Culture media, Endothelium, Cytology, Human cell culture

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