MYOSITIS IN LYME BORRELIOSIS - AN IMMUNOHISTOCHEMICAL STUDY OF 7 PATIENTS

Myositis is a rare complication of Lyme disease. In order to get infor mation about the pathogenesis of this disorder, muscle specimens of 7 patients suffering from myositis as a manifestation of Lyme borreliosi s were examined by immunohistology. Lyme spirochetes could be found in muscle biopsies of 6 patients. Infiltrates consisted mainly of macrop hages and T helper/inducer cells. The T4/T8 ratio was 1.7 in the endom ysium and 2.1 in the perimysium. Increased expression of MHC-I molecul es by several muscle fibers was observed in 2 subjects only. No MHC-II molecules were expressed by muscle fibers. Lymphocytes expressing the interleukin-2 receptor were detected in 2 patients. Leu-15+ and Leu-1 1+ cells were found only to a slight extent in 2 patients. In conclusi on the immunohistochemical findings in myositis due to Lyme borreliosi s are different from other manifestations of this disease, and also fr om other forms of myositis.