Leucocyte activation in erythema nodosum

Area of Science:

• Dermatology
• Immunology
• Cell Biology

Background:

• Erythema nodosum (EN) exhibits neutrophilic vascular reactions and inflammatory infiltrates in skin lesions.
• The precise role of activated neutrophils in EN pathogenesis remains unclear.

Purpose of the Study:

• To investigate the potential role of activated polymorphonuclear neutrophils (PMN) in erythema nodosum (EN) pathogenesis.
• To analyze reactive oxygen intermediate (ROI) production as a marker of neutrophil activation in EN patients.

Main Methods:

• Peripheral blood samples from 10 EN patients and 10 healthy volunteers were analyzed.
• Flow cytometry (FACS) using dihydrorhodamine 123 staining assessed ROI production by PMN.
• PMN activation was further tested using formylated methionyl-leucyl-phenylalanine and phorbol 12-myristate 13-acetate.

Main Results:

• EN patients exhibited a fourfold higher percentage of 'primed' ROI-producing PMN compared to controls.
• Stimulation of PMN increased ROI production per cell but did not alter the percentage of activated cells.
• The percentage of ROI-producing PMN correlated with clinical severity in EN patients.

Conclusions:

• Activated PMN and their ROI production are implicated in the pathogenesis of erythema nodosum.
• ROI may contribute to EN by causing oxidative tissue damage and promoting inflammation.