Resposta imunológica na saliva aos antígenos de superfície do M. leprae: implicações clínicas

Abstract

CAPÍTULO II -Leprosy is a chronic infectious neurodermatological and disabling disease whose etiologic agent is Mycobacterium leprae. Despite being a very ancient disease, the pathogenic mechanisms remain poorly understood and require concerted effort to clarify the relationship between the parasite and the host. PGL-1 is a specific cell wall component of M. leprae found in large quantities in infected human tissues and can be identified in saliva, but its participation in mucosal immunity is not yet clarified. This study evaluated the presence of secretory IgA (sIgA) anti-PGL-1 by indirect ELISA in leprosy patients and their contacts, correlating it with the clinical form, operational classification, and the occurrence of leprosy reaction in patients. Significant differences occurred between the values of the ELISA Index (EI) group of patients and endemic controls (p = 0.01). In the PB form (OR 12.09, CI 1.31 - 111.66; p = 0.028) when compared to the MB form (OR 0.94, CI 0.38 – 2.29; p = 0.899), a larger and significant association between positive salivary sIgA with reactions was noted. Among the clinical forms, there was an association between the positivity of salivary EI and the appearance of leprosy reactions in BT forms (OR 7.12, CI 2.07 - 24.54; p = 0.002). This suggests that the saliva sIgA anti-PGL- 1 is a leprosy type 1 reaction marker in BT forms and can be used as a prognostic marker in the diagnosis of these patients to identify those at higher risk of nerve damage. CAPÍTULO III - The development of disability in the individual affected by leprosy is a critical point associated with a context of social exclusion and stigma. Understanding the molecular and immunological mechanisms of nerve damage induced by M. leprae is a necessary step in the control of leprosy, preventing progression to a harmful neuropathic condition. Using ELISA, this study assessed the presence of salivary secretory IgA (sIgA) anti-LAM in leprosy patients and their contacts. The PB patients (PB) showed an association between the positivity of anti-LAM sIgA and the appearance of leprosy reactions, in which all the patients in this group who developed reactions were LAM positive (OR 19.34; p = 0.048). A distinct pattern was observed in the sIgA anti-LAM between groups: naïve patients, patients who completed MDT, contacts, and endemic controls. When the behavior of anti-LAM sIgA in the group of contacts was evaluated, there was a higher percentage of positive individuals in contacts with a positive Mitsuda test, suggesting that sIgA anti-LAM may be a possible indicator of cellular immunity conferred to contacts. Patient monitoring revealed that when the anti- LAM sIgA values are kept high or increase the diagnosis at discharge from MDT, the number of reactions increases, and if the indexes decrease, the chance of occurrence of reactions is lower. Our data suggest that monitoring of sIgA anti-LAM in patients undergoing treatment can become an important tool in detecting risk groups for the development of leprosy reactions.