Fig. 3.

CEACAM6 (C6) association with surfactant after density gradient flotation. A: Western blot. Three pooled samples of d14 infant surfactant pellets were subjected to KBr gradient centrifugation, and the surfactant band was obtained. Equal fractions (2 μg of PL) of the initial pellet sample (Pre) and postcentrifugation surfactant band (Post) were analyzed by Western blotting for CEACAM6 and SP-A. Pre and Post CEACAM6 bands are similar, whereas the SP-A signal is reduced for each Post sample. B: concentration of proteins in the surfactant band. Content of SP-A and CEACAM6 was determined by densitometry of the Western. SP-B content was measured by immunodot assay, and total protein was determined by the BCA assay. SP-B and CEACAM6 concentrations were identical in the pre- and postgradient surfactant compared with ∼40% of SP-A and total protein after flotation. Values are means ± SE; n = 3. P < 0.01 for Pre vs. Post for protein and SP-A.