Evaluation of Previously Assigned Antibody Concentrations in Pneumococcal Polysaccharide Reference Serum 89SF by the Method of Cross-Standardization

Abstract

An enzyme-linked immunosorbent assay (ELISA) and the antibody concentrations assigned to different pneumococcal capsular polysaccharide types were used to estimate concentrations of antibody to additional pneumococcal types in reference serum 89SF and to confirm assigned antibody values. This was possible because the slopes of curves of antibody binding to all polysaccharide types evaluated (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F) were similar. The point estimates for total anti-pneumococcal antibody and immunoglobulin G (IgG) antibody determined by cross-standardization by an ELISA based on use of methylated human serum albumin (mHSA) to improve the efficiency of polysaccharide binding to the ELISA plate differed by less than 40% from those reported by Quataert et al. (Clin. Diagn. Lab. Immunol. 2:590–597, 1995) for types 1, 4, 6B, 7F, 9V, 14, 18C, and 23F. However, large differences were found between the assigned values and those obtained by our mHSA ELISA for types 3 and 19F. The mHSA ELISA and the direct polysaccharide coat ELISA may not measure antibodies to the same epitopes on polysaccharides of types 3 and 19F. The functional importance of these different antibody specificities is being investigated. We have thus confirmed the assigned IgG antibody values for most types by a different method and have extended antibody assignments to several additional types.

Dependence of correlations between antibody titres and opsonophagocytosis on pneumococcal serotype and patient morbidity in pre- and post-pneumococcal vaccination states

“…ELISAs were performed as described previously [17,18], with minor modifications to determine the concentration of specific anti‐capsular IgG to pneumococcal serotypes 6B, 14 and 23F. In brief, serum reference standards, quality control specimens and test specimens were adsorbed with a 1:50 dilution of a 10 mg/L preparation of cell‐wall polysaccharide (Statens Seruminstitut, Copenhagen, Denmark).…”

Determination of Antibody Responses of Elderly Adults to All 23 Capsular Polysaccharides after Pneumococcal Vaccination

“…A reference pooled human serum sample was standardized by comparing it with the international standard serum 89-SF (a gift of Carl Frasch, Food and Drug Administration, Bethesda, Md. ), for which the concentrations of vaccine type-specific IgG antibody have been established for 15 of the 23 vaccine serotypes (6,24). Concentrations of specific IgG antibody in serum 89-SF for serotypes without established standard values were determined by a cross-standardization method (6): PPS 8, 5.74 g/ml; PPS 9N, 7.90 g/ml; PPS 10A, 5.41 g/ml; PPS 12F, 4.16 g/ml; PPS 15B, 14.20 g/ml; PPS 17F, 8.19 g/ml; PPS 22F, 5.48 g/ml; and PPS 33F, 7.69 g/ml.…”

“…at 0.5 g per 100 l of phosphate-buffered saline per well by overnight incubation at 4°C. Because inspection of standard curves suggested that PPS 3 did not bind reproducibly to polystyrene plates, as suggested by others, plates were first coated with methylated albumin prior to capture with PPS 3, as described (6). All sera and standards were preadsorbed with cell wall polysaccharide (10 g/ml of serum; Statens Seruminstitut, Copenhagen, Denmark) at room temperature for 30 min.…”

Development and evaluation of a rapid multianalyte particle-based flow cytometric assay for the quantification of meningococcal serogroup B-specific IgM antibodies in sera for nonculture case confirmation

“…Table 3. Percentage agreement between the serogroup B microsphere assay and enzyme-linked immunosorbent assay (ELISA) using 0.2 and 0.25 mg mL À1 as the cut-off levels As the standard curve for serogroup B ran parallel to that of serogroups A and C, it was possible to assign a serogroup B IgM concentration (0.51 mg mL À1 ) to CDC 1992 using the method of cross-standardization (Concepcion & Frasch, 1998), thus allowing actual IgM concentrations to be derived.…”