IgM and IgG response to pneumococcal polysaccharide vaccine in normal individuals and individuals splenectomized due to trauma.

Twenty-one young, splenectomized, healthy individuals (S group) and ten healthy individuals (K group) were vaccinated with a 14-valent pneumococcal polysaccharide vaccine. All individuals in the S group were splenectomized due to abdominal trauma. IgM and IgG antibodies against each of the 14 pneumococcal serotypes were determined by enzyme-linked immunosorbent assay. Serum concentrations of IgM and IgG were measured by radial immunodiffusion. The mean prevaccination IgM pneumococcal antibody level was lower in the S group than in the K group for most of the serotypes. The mean total serum IgM was considerably reduced in the S group. Vaccination induced a significant IgM pneumococcal antibody response in both groups, but the response tended to be smaller in the S than in the K group. These findings may appear compatible with suboptimal immune regulation in the splenectomized individuals. There were small variations between the total serum IgG and the prevaccination IgG pneumococcal antibody level in the two groups. Both groups obtained a significant IgG pneumococcal antibody response after vaccination to most of the serotypes.