Type-1 or reversal reactions are the major cause of nerve damage and disability in
leprosy. We wished to determine whether there were any clinical or
laboratory markers that identified patients with an increased risk of type-1 reaction. 42 (31%) of 136 Nepalese
borderline leprosy patients (97 male, 39 female; age range 7-73 years) had a type-1 reaction during the first 2 years of multi-
drug therapy. Before
therapy, 41 (98%) of the 42 patients were seropositive for
antibodies to one of three mycobacterial
antigens. Seropositivity for
IgM antiphenolic-glycolipid-1 (PGL-1)
antibodies, but not
IgG anti-
lipoarabinomannan or anti-Mycobacterium leprae 35 kDa
protein antibodies, was significantly associated with subsequent manifestation of a type-1 reaction (p less than 0.001). The concentration of
IgM anti-PGL-1
antibodies in serum was significantly higher in patients in whom a type-1 reaction developed. The risk attributable to anti-PGL-1 seropositivity was independent of
leprosy class, skin smear positivity, and the presence of other anti-M leprae
antibodies (adjusted odds ratio = 8.7, p less than 0.001). In the 87 patients who had a
lepromin test, anti-PGL-1 seropositivity and
lepromin reactivity were significant independent risk factors for subsequent reaction. 78% of patients with positive
lepromin reactivity and
IgM anti-PGL-1
antibodies had type-1 reactions. Patients with these risk factors should be carefully monitored during antimicrobial
therapy to permit early initiation of anti-inflammatory treatment thus minimising permanent nerve damage and resultant disability.