Mast Cells in Tuberculosis: Immune Regulation, Allergic Environments, and Pathological Mechanisms

Mast cells (MC) are key effector cells in allergic diseases and are increasingly recognized for their roles in the immunopathogenesis of tuberculosis (TB). In allergic conditions, MCs are hyperactivated, driving T-helper Type 2 (Th2)-skewed immune responses that may antagonize the T-helper Type 1 (Th1)-mediated immunity essential for controlling Mycobacterium tuberculosis (Mtb) infection. This immunological imbalance may contribute to increased TB susceptibility, altered granuloma dynamics, and accelerated fibrotic remodeling. Histopathological and in vivo studies have revealed that MCs are recruited to TB lesions, where they release a spectrum of mediators, including histamine, IL-17A, TNF-α, TGF-β, tryptase, and chymase. These mediators can either support initial immune defense or promote chronic inflammation and tissue damage, depending on context and regulation. Moreover, individuals with chronic allergic diseases such as asthma and allergic rhinitis may experience worse TB outcomes due to their baseline immune dysregulation. Environmental exposures (e.g., air pollution, smoking), genetic polymorphisms (e.g., IL-4 −589C/T, IL-13 R130Q), and gut-lung axis disturbances further modulate MC activity and TB pathogenesis. This review synthesizes current findings on MC involvement in TB, particularly in allergic settings, and highlights the need for epidemiological studies and mechanistic research. It also explores the promise of host-directed therapies (HDTs) that target MCs or their mediators, such as antihistamines, MC stabilizers, leukotriene inhibitors, and cytokine modulators, as novel adjuncts to standard TB treatment. Personalized approaches that consider immune profiles, genetic risk, and comorbid allergies may improve TB outcomes and inform future clinical guidelines.