Figure 4. Erythema nodosum leprosum is a pathological condition characterized by a robust inflammatory response involving the recruitment of neutrophils.

The detection of complement activation, immune complexes, increased CD4+/CD8+ T cell subset ratios, and a notable concentration of tumor necrosis factor-alpha (TNF-α) can be observed in both the lesions and the systemic circulation. There is a surplus of B lymphocytes and plasma cells, which exhibit the capacity to produce antibodies. CD8+ T lymphocytes secrete a repertoire of cytotoxic granule proteins, such as perforin and granzymes, that elicit apoptosis in target cells.

IFN-α: interferon-alpha, IFN-γ: interferon‐gamma, IL: interleukin

This figure was created by CB, one of the authors of this article, with Biorender.com.