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Measurement of the affinity of anti‐D in the serum of immunized mothers and in immunoglobulin preparations with unlabeled antibodies
Author(s) -
Debbia Martine,
Brossard Yves,
Lambin Patrick
Publication year - 2005
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/j.1537-2995.2005.04313.x
Subject(s) - polyclonal antibodies , antibody , monoclonal antibody , fetus , chemistry , medicine , chromatography , immunology , endocrinology , pregnancy , biology , genetics
BACKGROUND: Few data are available on the affinity of maternal anti‐D responsible for hemolytic disease of the fetus and the newborn (HDN) and of anti‐D used for the prophylaxis of that disease. A method was recently described to measure the affinity (K a ) of untagged anti‐D monoclonal antibodies (MoAbs). In this work, the same method was applied to determine the K a of polyclonal anti‐D. STUDY DESIGN AND METHODS: O R 1 r red blood cells (RBCs) were sensitized with increasing concentrations of native anti‐D in serum samples from immunized mothers and donors and in RhIG preparations. At equilibrium, the amount of anti‐D bound to RBCs was measured by enzyme‐linked immunosorbent assay. Scatchard and Langmuir equations were used to determine K a . RESULTS: The experimental data fitted well with the Scatchard equation (mean r 2 = 0.95) but a better correlation was observed with the Langmuir equation (mean r 2 = 0.99). The mean K a of anti‐D in 11 maternal serum samples, in 6 immunized donors, and in 5 lots of RhIG were 5.6 × 10 8 per M (from 2.8 × 10 8 to 12 × 10 8 /M), 3.9 × 10 8 per M (from 1.5 × 10 8 to 6.8 × 10 8 /M), and 3.4 × 10 8 per M (from 3.1 × 10 8 to 4.2 × 10 8 /M), respectively. The comparison of anti‐D affinity in 5 cases of HDN with fetal anemia and in 6 cases of HDN with postnatal anemia showed no significant difference. CONCLUSION: The method previously described for anti‐D MoAbs was applied to polyclonal anti‐D present in the serum of immunized subjects and in immunoglobulin preparations. The experimental data fitted well with the Langmuir equation, and the affinity of polyclonal of anti‐D was measured with accuracy.