Comparing factor VIII with collagen IV for immuno-staining of vessels

Introduction Factor VIII (F8) and collagen IV (C4) antibodies are used for quantifying vessels in tissue sections. We compared these two antibodies for vessels staining in bronchial biopsies (BB) in COPD. Methods BB from 7 healthy nonsmokers (H-N) and 28 COPD subjects were stained for both antibodies. Number, area and mean vascular size (MVS) (surface area /vessel number) of vessels in the lamina propria (LP) to the depth of 150 ìm were measured and compared between the two antibodies and are reported as median (range). Results Number of vessels was not significantly different between the two methods of staining. In COPD and H-N, vascular area (ìm2/ìm2 of LP x 100) stained with F8 was less than that with C4 [4.1 (1.8-8) vs. 6 (2-10.3), p<0.01 and 3.9 (2.6-8.7) vs. 6.8 (3.7-8.9), p<0.05]. MVS with F8 was less than that with C4 in COPD and H-N [112 (60-316) vs. 204 (110-457), p<0.01 and 70 (45-198) vs. 183 (67-286), p<0.05]. The COPD group had higher MVS compared to H-N with F8 staining [112 (60-316) vs.70 (45-198), p<0.05] but not C4. Conclusions F8 and C4 probably stain somewhat different structures in BB sections from both control and COPD subjects; F8 stains smaller and probably younger vessels. Higher MVS with F8 but not C4 in the LP of COPD group compared to H-N suggests predominance of older vessels in this compartment. Further investigation of angiogenic activity in COPD is needed.