Cell-cell recognition: relation to cell adhesion with special reference to adhesion of hepatocytes

Cell recognition is defined as an active process giving rise to a specific response. Cell adhesion is a good example of cell recognition when it can be demonstrated that the adhesion is mediated by molecules having specific binding properties. Such cell adhesion molecules have now been identified in several cellular systems. We have demonstrated that cell-cell adhesion between rat hepatocytes involves a 105,000 dalton cell surface glycoprotein (cell-CAM 105) and that other high molecular weight glycoproteins participate in the attachment of these cells to collagen. Using immunofluorescence we found cell-CAM 105 in the liver, the simple epithelia of the gastrointestinal tract, the kidney tubules and in the glandular epithelium of the parotid gland. In these tissues it was specifically located at the places of the junctional complexes. We have thus demonstrated that adhesion of adult rat hepatocytes is characterized by specificity both at the molecular and the cellular levels. However, the specificity at the cellular level was not complete, since the same cell-cell adhesion molecule was also present in some simple epithelia in addition to the liver.