Figure 3. Effect of competing rhSC on measurement of purified colostral SIgA and RV-SIg. Reported values are optical density units (OD, 450 nm) (Y axis) and the log10 of the rhSC concentration in μg/μl (X Axis) used to compete the binding of: (A) purified colostral SIgA (0.076 μg/ml); (B) a plasma sample from a child in which RV-SIg was presumably only RV-SIgA (RV-IgA+, RV-IgM-); and (C) a plasma sample from a child in which RV-SIg was presumably only RV-SIgM (RV-IgA-, RV-IgM+). Open dots in graphics show the concentration of rhSC inducing approximately 50% of inhibition and the dashed lines correspond to the signal observed when samples were competed with albumin at the same concentrations as for rhSC.