Expression of the alpha 2 beta 1 and alpha 3 beta 1 integrins at the surface of mesothelial cells: a potential attachment site of endometrial cells

Objective: To localize alpha 2 beta 1 and alpha 3 beta 1 integrins in the cell membrane of peritoneal mesothelium in vivo and in vitro. Design: Descriptive study using confocal and two-photon laser-scanning microscopy. Setting: University-based laboratory. Patient(s): Women without endometriosis undergoing surgery for benign conditions. Intervention(s): None. Main Outcome Measure(s): Peritoneal biopsies (n = 9) and mesothelial monolayer cultures (n = 4) were incubated with antibodies to the alpha 2 and alpha 3 subunits and to the intact alpha 2 beta 1 and alpha 3 beta 1 integrins. Specimens were examined with laser-scanning microscopy. Result(s): The alpha 2 and alpha 3 subunits and the intact alpha 2 beta 1 and alpha 3 beta 1 integrins were identified at the base of the mesothelial cells (i.e., toward the basement membrane). There was also expression of the alpha 2 and alpha 3 subunits and the intact alpha 2 beta 1 and alpha 3 beta 1 integrins at the cell surface (i.e., toward the peritoneal cavity). Conclusion(s): The resolution of the confocal and two-photon laser-scanning microscope enabled localization of integrins in mesothelial cells. The presence of alpha 2 beta 1 (collagen-laminin receptor) and alpha 3 beta 1 integrins (collagen-laminin-fibronectin receptor) at the base of mesothelial cells suggests a role for these molecules in adhesion to the basement membrane. The presence of these molecules at the cell surface suggests a potential locus for cell adhesion in such processes as endometriosis and cancer metastasis. (Fertil Steril(R) 2000;74: 579-84. (C) 2000 by American Society for Reproductive Medicine.).