ABSTRACT

One of the principal applications of monoclonal antibodies has been in the identifi­ cation, enumeration, localization, and isolation of individual types of cells from blood or solid tissues. As cells differentiate to carry out their specific functions, different genes are expressed, and the molecular composition of a cell, therefore, reflects its differentiation state. A molecule which is expressed selectively by a particular cell type can serve as a marker for that cell type. Monoclonal antibodies against such a marker molecule can be used to identify, count, find (in tissue), and isolate the cells carrying the marker. The most useful differentiation markers are on the outer cell membrane, since they can be identified without making the cell membrane permeable.