Anti-Pneumococcal Vaccine-Induced Cellular Immune Responses in Post-Traumatic Splenectomized Individuals

Splenectomy is associated with increased risk of overwhelming post-splenectomy infections despite proper anti-pneumococcal vaccination. As most studies concentrated on vaccination-induced humoral immunity, the cellular immune responses triggered in splenectomized patients are not yet well studied. The present study aims to investigate this area as it can contribute to the development of more effective vaccination strategies.

Five healthy and 14 splenectomized patients were vaccinated with pneumococcal conjugate polysaccharide vaccine (PCV) followed by pneumococcal polysaccharide vaccine according to the guidelines established by Advisory Committee on Immunization Practices. PBMC samples collected 0, 8, and 12 weeks after PCV immunization were in vitro stimulated with PCV. Levels of lymphoproliferation, T_H cell differentiation, and cytokine release were assessed by carboxyfluorescein succinimidyl ester labeling, intracellular cytokine staining, and ELISA, respectively.

While T_H1-dominated immune response was detected in both groups, asplenic individuals generated significantly lower levels of T_H1 cells following in vitro stimulation. Similarly, levels of IFN-γ, IL-4, and IL-17 release and lymphoproliferation were significantly lower in asplenic patients.

According to our data, splenectomy negatively influences the levels of PCV-induced lymphoproliferation, T_H1 differentiation, and cytokine release. Besides, PCV failed to induce T_H17-dominant immune response which is crucial for protection against extracellular pathogens.