Acquisition and alteration of adhesion molecules during cultured human mast cell differentiation

Background: Mature human mast cells express several types of adhesion molec ules on their surface. Interactions between extracellular matrix (ECM) and adhesion molecules may be important for the migration and localization of m ast cells and their precursors in tissues. Little is known about the regula tion of adhesion molecules on mast cells during their differentiation. Objectives: To clarify the evolution of adhesion phenotype and function, we examined the expression of adhesion molecules during cultured human mast c ell (CHMC) differentiation and tested adhesion of mature CHMCs to various E CM proteins. Methods: CHMCs were obtained by culturing human cord blood-derived CD34(+) cells in the presence of stem cell factor and IL-6. Indirect immunofluoresc ence and now cytometry was used to study cell surface expression of adhesio n molecules and other markers. Mature CHMCs were tested for adhesion molecu le function with immobilized matrix proteins. Results: At 1 week of culture, cells expressed CD11a, CD18, CD29, CD49d, an d CD49e. At 14 weeks of culture, more mature CHMCs expressed CD11b, CD11c, CD29, CD49b, CD49c, CD49d, CD49e, CD51, CD61, and CD54 and weakly expressed CD18 and CD11a. CD11c, CD51, and CD61 appeared de novo by 4 weeks of cultu re, whereas CD49b and CD49e appeared by 8 weeks. CD29 decreased at 4 weeks but returned to the identical levels of 1-week-old cells by 8 weeks. Compar ed with levels at week 1, the levels of CD11a, CD18, CD49d, and CD49e at 4 weeks and beyond decreased during culture. Expression of CD49a, CD49f, and alphad integrin was never detectable during CHMC differentiation. Fourteen- week-old CHMCs significantly adhered to the leucine-aspartic acid-valine-co ntaining connecting segment 1 fragment of fibronectin, the 120-kd argine-gl ycine-aspartic acid-containing fragment of fibronectin, vitronectin, and la minin through specific integrins. Conclusion: Expression of integrins and CD54 is differentially regulated du ring CHMC differentiation, and mature CHMCs can adhere to many ECM proteins . These changes may facilitate emigration from the bone marrow into the cir culation and ultimately contribute to the tissue homing and localization pa ttern seen with mature mast cells.