ALPHA-6 INTEGRIN DISTRIBUTION IN HUMAN EMBRYONIC AND ADULT TISSUES

Alpha 6 integrin is an adhesion molecule that connects cells with extr acellular matrix molecules of the laminin family. The laminin interact ion seems to be essential for cell differentiation during embryogenesi s and for the subsequent maintenance of tissue integrity in the adult. Alpha 6 integrin can also interact with lamininin-dependent cellular ligands and in this way plays a role in homing of leucocytes. Furtherm ore, in cancer biology alpha6 integrin has an important role in metast asis and as a possible new prognostic factor; exact knowledge of alpha 6 integrin distribution in normal human tissues is therefore a crucial element. By immuno-histochemical methods we have screened alpha6 inte grin expression of representative human tissues from the adult and the embryonic organism. All tested epithelia were alpha6 integrin positiv e, except for the endocrine cells of the pancreas and the adrenal glan ds. Heterogeneous staining was found on non-epithelial tissues. Strong staining was evident in peripheral nerves (Schwann cells), germ and S ertoli cells, endothelia, and smooth muscle cells of the myometrium. W eak staining was found in nerve cells of the stratum granulosum, the m icroglia, Kupffer's cells and stromal cells of the ovary. All fibrobla sts, striated muscle cells and astrocytes were negative. The tissue di stribution of alpha6 integrin and the semi-quantitative estimation of their expression level should provide a better understanding of alpha6 integrin function under normal and phathological conditions, in parti cular in tumour progression.