Unlocking the Immune Code: IL-5 Dynamics in BALB/c Mice Spleen Post-Exposure to Klebsiella pneumoniae Pili Protein 65.5 kDa

ObjectivesKlebsiella pneumoniae is a Gram-negative pathogen responsible for a range of hospital-acquired infections and is increasingly resistant to antibiotics. This study aimed to evaluate the immunogenic potential of a 65.5 kDa pili protein from K. pneumoniae by assessing its ability to induce Interleukin-5 (IL-5) production in the spleen of BALB/c mice, thereby exploring its suitability as a vaccine candidate. MethodsTwenty-one BALB/c mice were randomly assigned to three groups: control (PBS), adjuvant only, and pili protein. The animals received three intraperitoneal injections at 14-day intervals. The first dose was given with Complete Freund's Adjuvant (CFA), followed by two doses with Incomplete Freund's Adjuvant (IFA). Fourteen days after the final injection, spleens were collected, and IL-5 levels were measured using enzyme-linked immunosorbent assay (ELISA). ResultsThe group immunized with the 65.5 kDa pili protein showed a statistically significant increase in IL-5 levels compared to both the control and adjuvant groups (p < 0.001). This indicates that the pili protein effectively stimulates IL-5 production, a key cytokine in the Th2 immune response pathway. ConclusionThe 65.5 kDa pili protein of Klebsiella pneumoniae demonstrated the ability to enhance IL-5 production and elicit a Th2-type immune response in BALB/c mice. These findings support its potential as a promising vaccine candidate for preventing K. pneumoniae infections through stimulation of humoral immunity.