Bronchial epithelial cells release chemotactic activity for lymphocytes

Lymphocytes can frequently be observed in association with bronchial tissues. One mechanism that might account for this association is that bronchial epithelial cells might release chemotactic factors for lymphocytes. To test this hypothesis, bovine bronchial epithelial cells were cultured in serum-free media, and the supernatant fluids were harvested and evaluated for lymphocyte chemotactic activity using a blind-well chamber technique. Media alone attracted few lymphocytes (12 ± 2 cells/high power field), but in contrast, there was a significant increase in the number of cells attracted by supernatant fluids obtained from bronchial epithelial cell cultures (40 ± 6 cells/high power field, P = 0.002). The activity was dose dependent and was demonstrated to be chemotactic activity by checkerboard analysis. Partial characterization of the activity revealed it was not extractable into ethyl acetate but was partially inactivated by trypsin and heat (100 °C, 15 min). The responding cells were predominantly T-helper lymphocytes as shown by monoclonal antibody staining, with a smaller proportion being B-lymphocytes. Molecular sieve column chromatography revealed multiple peaks of lymphocyte chemotactic activity, with three of the peaks preferentially attracting T-helper lymphocytes and one of the peaks preferentially attracting B-lymphocytes. These data demonstrate that bronchial epithelial cells can release chemotactic factors for lymphocytes and suggest that bronchial epithelial cells may modulate their local population of immune effector cells.