Transplantation, 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. 

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. 

Thus, cell surface markers remain a useful tool and have widespread use, as evidenced by the stem cell literature. Limitations, explained in the bone marrow transplantation literature, highlight the need for the development of new methods for identifying stem cells in the emerging field of cell therapy for cardiac diseases. Indeed, functional assays will likely play an important role in stem cell selection and classification in the future. 

There is another aspect of immune function that is affected by the CaMK cascade. This aspect is the maintenance of hematopoietic stem cells that reside in bone marrow and give rise to blood. These cells are clinically important in bone marrow transplants. CaMKIV is expressed in the hematopoietic progenitor population that contains stem cells and are called KLS cells (based on the status of three cell surface markers c-Kit+, Sca-1+, Liir/low). Bone marrow from Camk4 / mice was found to contain a decreased number of KLS cells, as well as a decreased number of leukocytes in the blood (Kitsos et al., 2005). Moreover, the KLS cells from Camk4 / mice are functionally impaired and unable to reconstitute blood upon bone marrow... 

Proteins are the most abundant and diverse class of antigens to which the immune system can respond. This class includes toxins, allergens, products of infectious organisms, and transplantation antigens. Also included in this class are proteins that are of particular interest to archaeologists, such as blood and tissue proteins, which may be soluble or found on the cell surface, secreted or nonsecreted. 

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