Immunological Mechanisms in Filarial Infections

Filarial infections, caused by nematodes such as Wuchereria bancrofti, Onchocerca volvulus and Brugia spp., impose a heavy global burden, affecting hundreds of millions. Host defence begins with innate recognition of parasite‐derived molecules by pattern‐recognition receptors on macrophages, dendritic cells and innate lymphoid cells. This primes a type 2 immune response characterised by interleukin-4, IL-5 and IL-13, recruitment of eosinophils and development of alternatively activated macrophages. Concurrently, regulatory circuits involving IL-10, transforming growth factor-β and regulatory T cells modulate inflammation and facilitate parasite survival. Filarial larvae further manipulate host immunity by releasing excretory–secretory products and extracellular vesicles that alter antigen presentation and T-cell polarisation. The interplay between protective mechanisms—such as eosinophil-mediated larval killing—and immunomodulatory strategies underlies both chronic infection and the pathology of lymphedema, hydrocele and tropical pulmonary eosinophilia. Insights into these processes are guiding vaccine design, immunotherapeutic targeting and novel diagnostic approaches.

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Immunological Mechanisms in Filarial Infections publication trend

The graph below shows the total number of articles in immunological mechanisms in filarial infections across all publications each year (not limited to Nature Index journals).

Technical terms

Microfilariae: The larval form of filarial nematodes found in the bloodstream; their presence in tissues triggers specific immune responses.

Extracellular Vesicle: A small, membrane-bound particle released by cells or parasites that carries bioactive molecules to modulate host immunity.

Type 2 Immunity: An immune programme dominated by IL-4, IL-5 and IL-13, activation of eosinophils and alternatively activated macrophages, tailored to combat helminth infections.

Regulatory T Cell: A CD4+ T-cell subset producing anti-inflammatory cytokines (IL-10, TGF-β) that restrains excessive immune activation and tissue damage.

Eosinophil: A granulocytic leukocyte that releases cytotoxic proteins and cytokines to destroy helminths and can contribute to both protective immunity and pathological inflammation.

References

1. Brugia malayi filarial helminth-derived extracellular vesicles suppress antigen presenting cell function and antigen-specific CD4+ T cell responses. Frontiers in Immunology (2024).
2. Repeated sensitization of mice with microfilariae of Litomosoides sigmodontis induces pulmonary eosinophilia in an IL-33-dependent manner. PLOS Pathogens (2024).
3. Identification and characterization of a novel nematode pan allergen (NPA) from Wuchereria bancrofti and their potential role in human filarial tropical pulmonary eosinophilia (TPE). PLOS Neglected Tropical Diseases (2024).