FIG. 1.

Binding of viable M. pneumoniae cells to hSP-A. [³⁵S]methionine-labeled M. pneumoniae cells were incubated with increasing concentrations of hSP-A with or without 1 mM CaCl₂ for 2 h at 37°C. BSA served as the control for nonspecific binding, and this value represented less than 2.5% of Ca²⁺-dependent binding. Values represent the means and standard deviations of triplicate wells from which background counts were subtracted. In parallel experiments the effect of EDTA (10 mM) on mycoplasma binding was compared. Also, radiolabeled mycoplasma cells were pretreated with trypsin (10 μg/ml, 10 min) to determine the extent of protease-sensitive binding. P ≤ 0.02 versus CaCl₂.