IMMUNOLOGICAL EVALUATION OF ERYTHEMA-NODOSUM IN TULAREMIA

During two tularaemia outbreaks in the Bursa region of Turkey in 1991. a total of 9 8 patients were diagnosed and evaluated. Thirteen of the se patients had erythema nodosum, which is accepted as a secondary ski n manifestation. The patients with erythema nodosum, 21 patients witho ut any skin lesions, and 20 healthy controls were studied. Comparable elevations of levels of IgG, IgA, and IgM were detected in the two tul araemia groups. There was no difference in complement C3c and C4 level s between the groups. All of the patients with erythema nodosum had el evated circulating immune complex (CIC) levels, when compared with the patients without skin lesions and the control group. The acute phase response (C-reactive protein [CRP] and erythrocyte sedimentation rate [ESR]) of the erythema nodosum group was significantly higher than the patients with normal skin, and healthy controls (P<0.001). Serum tran sferrin levels were significantly decreased in both of the tularaemia groups (P<0.001). Serum soluble interleukin-2 receptor levels (SIL-2R) were significantly elevated in both tularaemia groups (P<0.001), and the elevation was more marked in the erythema nodosum group (P<0.05). Histopathological evaluation of biopsies from two patients with erythe ma nodosum showed dermal oedema, a perivascular lymphocytic infiltrate , and panniculitis. No immunoglobulin or complement deposits were dete cted on immunofluorescence. Erythema nodosum in the course of tularaem ia is associated with many immunological changes, although it is not c lear whether these findings are related to the increased tissue respon se, or whether they play a role in the pathogenesis of the erythema no dosum.