Antibodies to mycobacterial arabinomannan in leprosy: correlation with reactional states and variation during...

An enzyme-linked immunosorbent assay was used to measure antibody to mycobacterial arabinomannan in serial serum specimens obtained over the initial 12-31 months of therapy from nine patients with leprosy. The antibody level in pretreatment sera was directly proportional to the quantity of Mycobacterium leprae present in each patient as assessed by six-site scrapings (r = 0.75). The three patients with the lowest antibody levels (OD 0.1-0.3) had uncomplicated courses and their levels declined slowly with treatment. Three patients with intermediate antibody levels (OD 0.7-1.1) each experienced a reversal reaction during therapy; serial antibody titers in all three followed a triphasic pattern over the course of the reaction. The two patients who developed erythema nodosum leprosum during therapy had extremely high levels of antibody initially (OD greater than 1.5), which fell slowly with time and which were unaffected by the reactional state. The pretreatment antibody level to arabinomannan reflects the amount of M. leprae present and may have predictive value for the development of reactional states.