Tight junction barrier function assayed in H413 clone-1 epithelial cell monolayers treated with anti-CD24 peptide antibody. Antibody to CD24 reduces passage of fluorochrome-labelled dextran across H413 epithelial cell monolayers. Due to passage of dextran into the lower compartment reaching equilibrium after the 7th hour, the rate of transfer was calculated over the first 5 hours. Regression analysis representative of three independent experiments for time points from triplicate cultures (showing mean values ± s.e.m.). Cultures were permeable for the translocation of low molecular weight dextran (Alexa Fluor 647 10 kDa, ** refers to P < 0.01, paired t-test), but were impermeable to high molecular weight dextran tetramethylrhodamine (TMR, 2 MDa).