Cell surface antigens

Boyer, C.M., Lidor, Y., Lottich, S.C., and Bast Jr., R.C. (1988) Antigenic cell surface markers in human solid tumors. Antibody, Immunoconjugates, Radiopharm. 1, 105. 

CD antigens Cell surface antigens present on leucocytes... 

Antineoplastic. Humanized mAb specific to lymphocyte antigen (cell surface glycoprotein,CD52). IgGl with human variable framework and constant regions and murine CDRs. Produced in CHO cells. 

Class 1 and class II MHC molecules bind peptide antigens and present them at the cell surface for interaction with receptors on T cells. The extracellular portion of these molecules consists of a peptide-binding domain formed by two helical regions on top of an eight-stranded antiparallel p sheet, separated from the membrane by two lower domains with immunoglobulin folds. These domains are differently disposed between the two protein subunits in class I and class II molecules. 

Frye, C. D., and Edidin, M., 1970. The rapid intermixing of cell surface antigens after formation of monse-hnman heterokaryons. of Cell... 

In addition to antibodies, the immune system also consists of bone-marrow derived lymphocytes, or B cells, and T cells that come from the thymus gland, both of which (indirectly) produce antibodies. These cells, in turn, may be helped by helper cells (= H) and suppressed by suppressor cells (= S). Helper cells may be alarmed as to the presence of antigens by macrophages (= M) that eat the antigens and leave parts of their meal on their cell surface. 

Cellular therapies in transplantation and cancer are based on specific cells separated or sorted from human blood, bone marrow, or cord blood by means of their specific cell surface markers or cell differentiation antigens, e.g., CD3, CD4, CD8, CD 14, CD 19, and CD34. For example, the CD34+ stem cells, especially those derived from human embryos, have the capacity to differentiate in culture to generate different somatic cells, e.g., liver cells, heart cells, neurons, etc. This exploding field of research is now termed regenerative medicine. 

The human leucocyte antigen (HLA) system is the general name of a group of genes in the human major histocompatibility complex (MHC) region on human chromosome 6 (mouse chromosome 17) that encodes the cell-surface antigen-presenting proteins. 

Molecules released by exocytosis fall into three categories (1) They can attach to the cell surface and become peripheral proteins, eg, antigens. (2) They can become part of the extracellular matrix, eg, collagen and glycosaminoglycans. (3) They can enter extracellular fluid and signal other cells. Insulin, parathyroid hormone, and the catecholamines are all packaged in gran-... 

The microbial cell surface constitutes a multiplicity of different antigens. These antigens may be common to different species or types of microorganisms or may be highly specific for that one type only. 

These T cells recognize peptide antigens bound to Class 1 MHC molecules on the surface of the target cell. During viral infections, viral peptides bind to selfMHCl molecules and are subsequently expressed on the cell surface. The MHCl molecules of transplanted tissues are themselves recognized by the Tc cells. 

Drugs frequently bind to blood elements directly (e.g. penicillin to erythrocytes) and the antibodies to the resultant complex react with, and damage, cells coated with the drug. Viruses, especially those that bud, become associated with the host cell surface antigens with the resultant generation of Tc cells. 

It is suggested that altered cells which could be potentially malignant are recognized by the immune system and eliminated. This must mean that cancer cells possess new antigens on their cell surface. These antigens have been identified and can be categorized into three groups. 

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