Figure 3.

The integrin αvβ8 inhibits airway epithelial proliferation in bronchial fragments. Airway fragments were cultured in individual wells for 2, 4, and 6 days in the presence or absence of a neutralizing anti-β8 Ab. Cell proliferation was assessed using Ki-67 immunostaining as a surrogate proliferation marker. Ki-67-labeling index was defined as the percentage of Ki-67-positive airway epithelial cells present in three random sections of each fragment. Each circle represents one fragment. a: Time course demonstrating that proliferation is significantly increased at days 4 and 6 of culture. The maximal increase is seen at day 4. The number of proliferating cells is significantly higher in anti-β8-treated (closed circles) relative to nontreated fragments (open circles) at day 4 of culture. The bar indicates the mean value. Each circle represents a single fragment. b: The experiment shown in a is shown in bar graph form to show SE. c: The experiment shown at day 4 in a is compared to two sequential experiments, each performed with fragments obtained from a different patient, using anti-β8 Abs (closed circles) compared to an isotype-matched control Ab (open circles). d: The experiment shown in c is shown in bar graph form to show SE. All three experiments show significant differences in cell proliferation between anti-β8 and control treated groups. *, P < 0.05; **, P < 0.001.