Assessing Humoral and Cellular Immunity in a Rat Model of Staphylococcal Bacterial Pneumonia

• Wasan Abdulateef Majeed

  Department of Biology, College of Education for Pure Science, University of Diyala

• Ola Abdulkareem Kadhim

  Department of Biotechnology, College of Science, University of Anbar

• Zainab Hussein Mahdi

  Department of Biology, College of Education for Pure Science, University of Diyala

General Background: Staphylococcus aureus pneumonia remains a major global health concern due to its virulence, biofilm formation, and rising methicillin-resistant strains, which complicate treatment. Specific Background: Understanding the interplay between humoral and cellular immunity is crucial for designing effective interventions, as both antibody-mediated and T-cell–mediated responses contribute to pathogen clearance. Knowledge Gap: While immune evasion strategies of S. aureus are documented, quantitative insights into the temporal dynamics of antibody production, T-cell proliferation, and cytokine release during infection are limited. Aims: This study aimed to evaluate the kinetics of humoral and cellular immune responses in a rat model of S. aureus pneumonia. Results: Infected rats exhibited significantly elevated IgM and IgG levels, with IgM peaking at day 14 and IgG progressively increasing. Splenocyte proliferation and cytokine production (IFN-γ, IL-4) were markedly enhanced, particularly at day 21, indicating strong Th1 and Th2 activation. Novelty: The study provides an integrated temporal profile of dual-arm immunity in experimental S. aureus pneumonia, demonstrating concurrent robust humoral and cellular activation. Implications: These findings highlight the necessity of targeting both antibody and T-cell responses in vaccine design, potentially guiding the development of immunotherapies for effective prevention and treatment of S. aureus pneumonia.
Highlight :

• IgM peaked on day 14, while IgG continued to rise until the end of the study.
• Splenocyte proliferation indicated strong T cell activation.
• Th1 and Th2 responses worked together to eliminate S. aureus from the lungs.

Keywords : Staphylococcus, Humoral, Cellular, Immunity, Rat Model

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