New insights in the pathogenesis of type 1 and type 2 lepra reaction

Abstract

In the current scenario of leprosy elimination, lepra reactions (LRs) remain a major persistent problem. Type 1 LR (T1LR) and type 2 LR (T2LR) are the major causes of nerve damage and permanent disabilities. The immunopathogenesis of LR have recently become an important field of research, since it may provide the relevant targets for the early detection and control of these episodes. Presently, there are no uniformly acceptable laboratory markers for LR. Genetic and serum markers in human host may predict susceptibility to reactions as well as progression of nerve damage in leprosy. Therefore, a deeper understanding of the molecular mechanisms involved in LR may provide a rational strategy for early diagnosis and prevention of the catastrophic consequences of LR.

Development of Type 2, But Not Type 1, Leprosy Reactions is Associated with a Severe Reduction of Circulating and In situ Regulatory T-Cells

“…This may explain why the search for immunological mediators, especially cytokines that could serve as surrogate markers for T1R and T2R, yielded inconsistent results. 4 Unfortunately the factors that initiate the development of leprosy are still completely unknown 5 ; for this reason, the risk factors of T1R and T2R remain an open issue. Hormonal and nutritional factors appear to have an influence.…”

Leprosy reactions: The predictive value of Mycobacterium leprae-specific serology evaluated in a Brazilian cohort of leprosy patients (U-MDT/CT-BR)

“…Leprosy reactions are immune inflammatory episodes that can cause irreversible handicaps, incapacity and deformities and no prognostic marker is currently available [9]. In the current study, the use of quantitative M .…”

“…One of the main difficulties in the clinical management of leprosy patients is the development of leprosy reactions that can occur anytime during the chronic course of the disease: before diagnosis, during treatment and even years after treatment release [2, 9, 10]. Leprosy reactions represent immunologically mediated episodes of acute inflammation that if not diagnosed and treated promptly can cause irreversible impairment of nerve function and permanent incapacities [11].…”

“…Leprosy reactions represent immunologically mediated episodes of acute inflammation that if not diagnosed and treated promptly can cause irreversible impairment of nerve function and permanent incapacities [11]. There are two major types of leprosy reactions: type 1 reaction (T1R) or reversal reaction (RR) which is associated with Th1-type immunity and type 2 reaction (T2R) represented mainly by erythema nodosum leprosum (ENL) which is related to Th2-type immune responses [9, 12]. Currently, there is no laboratory test able to predict the emergence of leprosy reactions among recently diagnosed patients.…”

Evaluation of key histologic variables in skin biopsies of patients of borderline leprosy with type 1 lepra reaction

“…The prevalence of type 1 reaction has been reported to vary from 8.9-35.7% in various prospective and retrospective studies. [3] It is believed to be caused by an increase in cell mediated immunity to mycobacterial antigen [4] and is associated with infiltration of CD4+ve lymphocytes in skin lesions and nerves which release interferon-γ (IFN-γ), interleukin-2 (IL-2), interleukin-12 (IL-12) and tumor necrosis factor-α (TNF-α) resulting in edema and painful inflammation. [5] Type 1 reaction tends to occur in patients in the borderline spectrum of leprosy including borderline lepromatous (BL) leprosy, mid-borderline (BB) leprosy, and borderline tuberculoid (BT) leprosy.…”