SP-D and GM-CSF affect the shape and size of the cells. (A-D) Adherent viable cells were grown in the absence or presence of SP-D (1 μg/ml) and/or GM-CSF (10 ng/ml) for 24 h. (A) Cells without any added proteins have relatively the same size and shape. (B) In the presence of SP-D, more cells became elongated in shape (arrows). (C) In the presence of GM-CSF, more cells became small, round or oval (arrowheads). (D) In the presence of both SP-D and GM-CSF, both populations (arrowheads, oval; arrow, elongated) are present. (E) Average cell size shown in the above conditions. Presence of GM-CSF significantly reduced cell size, reflecting the formation of small and spherical/oval cells. The sizes of at least 50 cells were measured in each category. Data are presented as means ± SEM; n = two independent experiments. The means were compared with respective controls using Dunnett's multiple mean comparison procedure (* p < 0.05). (F) Over one week time, many BAL cells changed into elongated and stopped internalizing foreign materials (labeled BSA). Number of cells that actively internalize the foreign material was quantified from the randomly selected images obtained in uptake assays. The increase in cell size was associated with decrease in % cells that internalize BSA. For percent cells that actively internalize, data are presented as the proportion of cells that were able to take up Alexa fluor 647-conjugated BSA in total number of cells present. The mean values were compared with Day1 value using Dunnett's multiple mean comparison procedure (* p < 0.05).