Carbohydrate-dependency of the agglutination of beads by SP-A. a) The pictures were taken under a light microscope by a 10 time magnification. Anti-goat antibody coated beads were incubated with goat anti-human SP-A antibody, 5 μl serum and an increasing amount of mannose (a: 0 mM mannose; b: 10 mM mannose; c: 20 mM mannose; d: 30 mM mannose; e: 40 mM mannose; f: 50 mM mannose). The agglutinate size decreased corresponding to an increasing mannose concentration. b) The figure shows a graph of the agglutinate size out of serum samples from three different test persons under varying mannose concentrations in a buffer containing calcium ions. SP-A concentration was 21 ng/ml in sample 1, 20 ng/ml in sample 2, and 20 ng/ml in sample 3. The higher the mannose concentration was, the smaller were the bead agglutinates. The experiments were repeated five times.