Figure 7. SP-A decreases the binding of CD14 to Re-LPS.

(A) CD14 (2 μg) was preincubated with increasing amounts of SP-A (0–40 μg) in a buffer containing 2 mM EDTA at 37 °C. Afterwards, proteins were incubated with 20 ng of ¹²⁵I-ASD-Re-LPS for 15 min at 37 °C in 50 μl of buffer and photolysed. The labelled proteins were then separated as described in Figure 6. When the buffer contained 0.5 mM Ca²⁺ instead of EDTA, similar results were obtained. (B) Time dependence of the fluorescence change when 2×10⁻⁷ M FITC-Re-LPS was incubated in the absence (line E) or presence of 0.075 μM CD14 alone (line A), 0.075 μM CD14+0.03 μM SP-A (line B), 0.075 μM CD14+1 μg/ml of an anti-CD14 antibody (28C5) (line C) and 0.03 μM SP-A alone (line D) in a buffer containing 1 mM EDTA at 37 °C.