BACKGROUND: Type 1 reactions are common in borderline leprosy, and can occur before, during or after multidrugtherapy (MDT). Recent papers suggest that these reactions could be a result of an imbalance between proinflammatory and anti-inflammatory citokines. OBJECTIVE: To understand better the physiopathology of type 1 reactions. METHODS: We studied skin biopsies from 10 non-treated patients with reactional borderline tuberculoid leprosy (BTR) and 10 from borderline leprosy with reversal reactions after the beginning of MDT (BRR), to compare morphological and immunological parameters by routine staining (H-E and Faraco-Fite) and immunohistochemical technics (CD4, CD8, CD20, CD79a, CD57, iNOS, IL-10, LAM and BCG). RESULTS: We found, in BRR group, stronger staining for iNOS into macrofages, fewer CD8+ T cells and more multivacuolated macrofages than BTR group (p<0,05). Despite the presence of viable bacilli in BTR and its absence in BRR, there weren't differences in baciloscopy and staining for mycobacterial antigens (LAM and BCG) between the groups. The number of IL-10+ cells was similar in both groups, but there was a negative correlation between this cytokine and the CD4:CD8 ratio only in BRR group (p<0,05). It was seen a tendency for a decreased specific infiltrate and increased number of NK cells in BRR group. CONCLUSIONS: The presence of many viable bacilli in a patient with partial cellular immunity could worse the immunological status (downgrading). Once started MDT, the reduction bacilli charge would improve cellular immunity (upgrading), with latter shift to innate immunity (Th3 response), evolving to cure.
Antibiotics, combined; Cytokines; Cell count; Granuloma; Leprosy, borderline; Nitric oxide
