FIG 1.

hSBA titers of serum samples determined using independent pooled human complement (hC′) lots. Two-fold serum dilutions from 1:4 to 1:1,024 were tested. Titers of <4 are shown as values of 2. (A) Comparison of hSBA titers for 15 samples using hC′ lots C12, C13, and C14 analyzed in the CBER laboratory; data for 3 samples tested with lot C11 are included. Indeterminate titers (n = 2) and titers of ≥64 with insufficient sample to test at higher dilutions (n = 2) are not shown. (B) Comparison of reported titers for 18 samples tested using hC′ lots C11, C12, and C13 in the PHE laboratory. Two samples with data available for only one hC′ lot are not shown. (C) Comparison of the median values of 14 samples between the CBER and PHE laboratories. Sample 33005 is not shown, as a valid median titer (panel B) was not determined.