Background: Leprosy is a chronic granulomatous infectious disease caused by the
bacterium Mycobacterium leprae. Leprosy "Type 1" reactions (T1R), reversal
reactions, occur in 30–40% of borderline patients with cellular immune responses to
M. leprae. "Type 2" reactions (T2R), also known as erythema nodosum leprosum
(ENL), occur only in lepromatous (LL) and borderline lepromatous (BL) patients with
a high bacterial load and little or no cellular immunity to M. leprae. Corticosteroids
alleviate symptoms in T1R and T2R, but many patients have multiple, recurrent
episodes. The Objective of the present study is to verify the validity of measuring
chitotriosidase activity and neopterin level, products of activated macrophages,
adenosine deaminase activity and monocyte chemoattractant protein-1 (MCP-1) as
markers of leprosy and to detect their values in diagnosis of different types of leprosy.
Methods: This study was conducted on 15 healthy subjects and 75 leprotic patients
that were classified into 5 groups [tuberculoid leprosy (TT), borderline tuberculoid
(BT), borderline borderline (BB), borderline lepromatous (BL), and lepromatous
leprosy (LL)], each group formed of 15 patients, depending on clinical,
bacteriological and histopathological pattern. Patients were further grouped with a
BI≥2 as multibacillary (MB, n=45), whereas those with BI<2 were grouped as
paucibacillary (PB, n=30). Thirty-four of the aforementioned patients were
diagnosed with reactions of which 17 had type II/erythema nodosum leprosum (ENL)
and 17 had type I/reversal reaction (RR). Reactions were treated using prednisolone
for 12 weeks. Venous blood sample was collected from each subject and processed for
estimation of the activity of chitotriosidase and adenosine deaminase, neopterin and
MCP-1 levels. Results: both chitotriosidase activity and neopterin level were elevated
in leprosy patients with significant elevation in MB than PB leprosy with significant
lowering in the patients with reactional leprosy after prednisolone therapy.
Adenosine deaminase activity was significantly elevated in TT, PB and reactional
leprosy. MCP-1 was significantly elevated in LL, MB and ENL. Conclusion:
chitotriosidase and neopterin could be considered as promising markers for
differentiation of MB from PB patients and useful for determining the response of
reactional leprosy to therapy. Adenosine deaminase could be useful in distinguishing
TT, PB and reactional leprosy. MCP-1 could be considered a fair marker in LL, MB
and ENL. In addition, these findings may provide new clues to the pathogenesis of
leprosy reactions.