DIFFERENTIAL EXPRESSION OF LAMININ CHAINS IN THE HUMAN MAJOR SALIVARY-GLAND

Laminin represents a macromolecule family. The heterotrimeric isoforms of laminin can be determined by immunohistochemical demonstration of the single chains. The laminin chain heterogeneity of the basement mem brane in adult human major salivary glands was evaluated in relation t o cellular differentiation of the epithelia and the stromal compartmen t. Monoclonal antibodies to the laminin alpha 1, alpha 3 (BM165) chain s and epiligrin reacted with the basement membranes of serous and muco us acini and of intercalated, striated and excretory ducts. As evidenc ed by a double-labelling technique, the alpha 2 chain showed a spatial association with the myoepithelium of the acini, whereas the ductal b asement membranes containing no myoepithelial cells were negative. Alm ost exclusively, beta 1 chain was detected in acinar basement membrane , beta 2 chain whereas in ductal basement membrane. gamma 2 chain is a unique chain belonging to the laminin-5 isoform. It was restricted to the ductal basement membrane. alpha 1, alpha 2, beta 1, beta 2 and ga mma 1 chains were detected in nerves of salivary tissue and alpha 1, a lpha 3, beta 1, beta 2 and gamma 1 chains and epiligrin in blood vesse ls. Our results indicate that the acinar ductal unit contains basement membranes with different isoforms, which relate to cell differentiati on and cell function. (C) 1998 Chapman & Hall.