Th2vastausta

Th2vastausta (Finnish for Th2 response) is a subset of the adaptive immune response mediated by T helper 2 cells (CD4+ T cells). It is characterized by the production of cytokines such as interleukin-4 (IL-4), IL-5 and IL-13, driven by the transcription factor GATA3 and signaling through STAT6. Naive CD4+ T cells differentiate into Th2 cells in a milieu rich in IL-4, often in response to extracellular parasites or allergen exposure.

The main functions of a Th2 response are to promote antibody production by B cells, especially class switching to IgE, recruit and activate eosinophils via IL-5, and enhance mucus production and airway hyperresponsiveness via IL-13. These effects help control helminth infections but can contribute to atopic and allergic diseases when dysregulated or chronic.

Th2 polarization occurs within an immune network that balances other pathways. Th2 differentiation is inhibited by Th1-associated cytokines such as IFN-γ and IL-12, while epithelial-derived cytokines such as TSLP, IL-25 and IL-33 can amplify Th2 responses in barrier tissues. Regulatory T cells and anti-inflammatory cytokines (e.g., IL-10, TGF-β) help limit Th2-driven inflammation.

Clinical relevance: A Th2-skewed response is a hallmark of many allergic diseases, including asthma, allergic rhinitis and atopic dermatitis, and can correlate with parasite clearance in helminth infections. Therapeutic approaches targeting IL-4 and IL-13 signaling aim to reduce Th2-mediated pathology.