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Clinical and Diagnostic Laboratory Immunology, 03 1997, 168-172, Vol 4, No. 2
MJ Rodrigo, M Miravitlles, MJ Cruz, J de Gracia, M Vendrell, C Pascual and F Morell
The aim of the study was to standardize an enzyme-linked immunosorbent
assay (ELISA) method for the quantification of immunoglobulin G (IgG) and
its subclasses (IgG1 and IgG2) against the 23-valent pneumococcal vaccine
and to establish the criteria for a normal response to the vaccine. Forty
healthy individuals (20 women and 20 men; mean age, 29 years) were studied.
All were vaccinated with the 23-valent pneumococcal vaccine; blood samples
were drawn just prior to and 3 weeks after immunization. Quantification of
specific IgG and its subclasses was performed by an ELISA with the vaccine
as the antigen. The linearity of the ELISA method was demonstrated by the
similar slopes of the linear regression lines generated from the titration
of sera with different antibody concentrations. The specificity of the
antibodies against the vaccine was demonstrated by (i) an absorption test
with pneumococcal vaccine, (ii) a cross-reactivity experiment with
Haemophilus influenzae type b polysaccharide, and (iii) affinity
chromatography with protein A-Sepharose. Response to the vaccine was
defined by using the lower level of the 90% probability interval (one-
tailed) for postimmunization-specific IgG, IgG1, and IgG2. By using this
cutoff, responders were considered to be those with an absolute increase in
antibody titers higher than 395 arbitrary units/ml for IgG, 0.350 A450
units for IgG1, and 0.314 A450 units for IgG2. Overall, 20 (50%) subjects
had IgG, IgG1, and IgG2 responses, 9 (22.5%) had IgG and IgG2 responses, 4
(10%) had IgG1 responses, 3 (7.5%) had IgG and IgG1 responses, and 4 (10%)
were nonresponders. Ninety percent of our population responded to the
23-valent pneumococcal vaccine. Up to 10% of healthy individuals may
respond to an IgG subclass without significant increases in total IgG
titers. The ELISA method that is described may be useful for evaluating the
specific antibody response against polysaccharides.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Characterization of specific immunoglobulin G (IgG) and its subclasses (IgG1 and IgG2) against the 23-valent pneumococcal vaccine in a healthy adult population: proposal for response criteria
Department of Biochemistry (Immunology Unit), Hospital General Vall d'Hebron, Barcelona, Spain.
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