Factors Influencing Pneumococcal Vaccination-Induced Total IgG, IgG2, and IgA Levels in Vaccinated Splenectomized Patients

Splenectomy is closely associated with a lifetime risk of pneumococcal and other encapsulated bacterial infections. In this study, it was aimed to investigate the change of antibody levels after vaccination against Streptococcus pneumoniae according to age, gender, years after splenectomy and the possible effect of splenectomy on IgG avidity. In addition the education and awareness levels of the participants about post-splenectomy vaccination and infectious diseases were also analyzed. In the first of the three phases of this study, 32 individuals with splenectomy were enrolled. The awareness of the patients about the possible risks after splenectomy was investigated with a simple questionnaire. Routine laboratory test results were obtained and clinical examinations were performed. In the second stage, total Ig values of 29 splenectomy patients were determined. In the third phase, 14 splenectomy and 5 healthy volunteers were vaccinated according to the Vaccination Practices Advisory Committee (ACIP) guidelines. Pneumococcal-specific antibody levels and IgG avidity were detected by enzyme linked immunosorbent assay (ELISA). It was determined that 68.8% of the splenectomized patients were unaware of their vaccination status and 78.2% of them were unaware of the increased risk of infectious diseases in asplenic conditions. . According to the hospital information management system, all 31 (96.87%) patients, except one, were vaccinated with PPV23. As expected, vaccinated patients exhibited high levels of vaccine-specific antibody production with IgG, IgG2, and IgA antibody concentrations of 321 ± 76.68 mg/l, 73.07 ± 8.273 mg/l, and 117.8 ± 14.94 mg/l, respectively, but unvaccinated patients had very low antibody (IgG, IgG2 and IgA antibody concentrations were 11.5 mg/l, 1.3 mg/l and 1.2 mg/l, respectively) levels. Although there was no correlation between antibody titers and gender, age groups or presence of fever history, the decrease in total IgG, IgG2 and IgA titers were strongly correlated with the time since splenectomy. Antibody titers were found to be significantly lower in splenectomized patients vaccinated more than 10 years ago. Routine laboratory results were at normal levels except for low platelet count. On the other hand, both splenectomized and healthy control subjects displayed similar IgG avidity index values (%61.8 ve %64.4% inhibition in control and splenectomized subjects, respectively) after the vaccination schedule. It was shown that post-splenectomy vaccination with PPV23 induced high levels of pneumococcus-specific antibody production that can last for more than five years. It was determined that more efforts should be made to increase the level of knowledge about pneumococcal and other overwhelming post-splenectomy infections (OPSI) as the awareness of the patients about the risks of infection after splenectomy was poor. In particular, patients with splenectomy operation more than 10 years ago should be very careful about being asplenic as they were determined to have significantly lower level of vaccine-specific antibody production. Our study was also the first to show that splenectomy does not alter IgG avidity induced by pneumococcal vaccination. © 2022 Ankara Microbiology Society. All rights reserved.