Oxide-dependent adhesion of the Jurkat line of T lymphocytes

The adhesion force of Jurkat cells was measured using atomic force microscopy (AFM) in aqueous solution at pH 7.2 on six metal oxide surfaces, namely, two quartz (alpha-SiO2) crystal faces, amorphous SiO2 glass, rutile (alpha-TiO2), muscovite mica (KAl2(AlSi3O10)(OH)2), and polycrystalline corundum (alpha-Al2O3). We show quantitatively for the first time that the T lymphocyte adhesion force and adhesion work correlates with substrate point of zero charge, indicating greater adsorption on surfaces with smaller negative charge. Adhesion events also exhibited sawtooth-shaped force-distance profiles indicative of protein bonds. No significant correlations were found with oxide Hamaker constants, indicating negligible contributions from van der Waals forces, nor with surface roughness. These results suggest that, when cell-surface receptors are not activated, Jurkat cell adhesion is dominated by specific interactions related to the unfolding of modular glycoproteins or other proteins that are not unique to T-cell surfaces and by electrostatic forces between negatively charged glycoproteins and variably charged oxide surfaces. Our results have implications for the interactions of immune system cells with metal oxides present in the human body either by design as in biomedical applications or inadvertently such as inhaled mineral dust particles in the lung.