POST-IMMUNIZATION PNEUMOCOCCAL ANTIBODY-TITERS AND IGG SUBCLASSES

IgG antibodies against pneumococcal polysaccharides are found predomin antly within IgG subclass 2. We wished to evaluate retrospectively IgG subclasses and post-immunization pneumococcal antibody titers in chil dren with recurrent respiratory infections. We examined total immunogl obulin levels and IgG subclasses, as well as pneumococcal antibody tit ers against serotypes 3, 7F, 9N, and 14 present 4-6 weeks after pneumo coccal immunization in 56 children 2-18 years old. Titers >200 ng Ab N /ml to any of the 4 serotypes tested were arbitrarily considered prote ctive. Four patients did not have protective antibody levels against a ny of the 4 serotypes tested following vaccination. Of those, 3 had no rmal IgG subclass levels and 1 had an IgG2 subclass deficiency. Of 3 a dditional patients with IgG2 deficiency 2 had protective antibody leve ls to only 1 serotype and 1 had protective antibody levels to 2 seroty pes. Furthermore, in 2 patients with undetectable IgG2 at the time of immunization, the response was only transient. We conclude that patien ts with IgG2 deficiency may not develop protective antibody levels to all pneumococcal serotypes and that some may have deficient memory for IgG anti-pneumococcal polysaccharide antibodies. (C) 1996 Wiley-Liss, Inc.