The effects of chemotherapy on antibody levels in lepromatous patients

Recent Laboratory Advances in Diagnostics and Monitoring Response to Treatment in Leprosy

The present review briefly summarizes the highlights of the recent advances in Mycobacterium leprae-specific tests for early diagnosis of leprosy. In addition to establishing the diagnosis of clinical cases of leprosy, these tests have also been used to detect subclinical infections in endemic population. Several attempts have been made from 1980 onward for standardization of specific diagnostic assays for early detection of leprosy. Brief account about the development and use of these assays has been described in this review article.

Application of RLEP real-time PCR for detection of M. leprae DNA in paraffin-embedded skin biopsy specimens for diagnosis of paucibacillary leprosy

The TaqMan real-time polymerase chain reaction (PCR) assay was evaluated systematically with respect to the standard curve, linear range, and used for detecting Mycobacterium leprae DNA in paraffin-embedded skin biopsy specimens from 60 confirmed leprosy patients and three healthy individuals and 29 other dermatoses and bacterial DNA from 21 different species. The test was further evaluated with 51 paucibacillary (PB) patients. The results showed that the test had good sensitivity (8 fg) and good specificity with no cross-reactivity with 21 other bacterial species and the control specimens, except one with Xanthomatosis. The real-time PCR detection rate for the 51 PB specimens was 74.5% (38 of 51). We conclude that the real-time PCR test is a useful adjunct test for diagnosing early stage or PB leprosy cases.

Use of anti-PGL-1 antibodies to monitor therapy regimes in leprosy patients

The suitability of IgM antibodies to PGL-1 for monitoring the response to multidrug therapy (MDT) was sequentially tested by ELISA in 105 leprosy patients, and bacterial indexes (BI) were also determined. Patients were divided into 3 groups: group 1, 34 multibacillary (MB) patients treated for 12 months with MDT-MB; group 2, 33 MB patients treated for 24 months with MDT-MB, and group 3, 38 paucibacillary (PB) patients treated for 6 months with MDT-PB. Untreated MB patients exhibited higher antibody levels (mean +/- SEM): group 1 (6.95 +/- 1.35) and group 2 (12.53 +/- 2.02) than untreated PB patients (1.28 +/- 0.35). There was a significant difference (P < 0.01) in anti-PGL-1 levels in group 1 patients: untreated (6.95 +/- 1.35) and treated for 12 months (2.78 +/- 0.69) and in group 2 patients: untreated (12.53 +/- 2.02) and treated for 24 months (2.62 +/- 0.79). There was no significant difference between untreated (1.28 +/- 0.35) and treated (0.62 +/- 0.12) PB patients. Antibody levels correlated with BI. The correlation coefficient (Pearson's r) was 0.72 before and 0.23 (P < 0.05) after treatment in group 1 and 0.67 before and 0.96 (P < 0.05) after treatment in group 2. BI was significantly reduced (P < 0.01) after 12 and 24 months on MDT (group 1: 1.26-0.26; group 2: 1.66-0.36). Our data indicate that monitoring anti-PGL-1 levels during MDT may be a sensitive tool for evaluating treatment efficacy. These data also indicate that the control of leprosy infection can be obtained with 12 months of MDT in MB patients.

Leprosy serology using PGL-I: a systematic review

Serology using a species-specific antigen for Mycobacterium leprae, PGL-I, could be a marker for the bacterial load of patients with leprosy. Various studies have identified the potential use of serology in the classification of patients for treatment purposes, case monitoring, identification of the risk of relapse and selection of household contacts with a higher risk of contracting the disease. A systematic review of the literature was conducted and 26 articles were included in this comparative analysis. The results of the use of PGL-I serology in different situations, its limitations and possible applications were evaluated. Studies show the efficacy of PGL-I serology in the classification of patients, treatment monitoring and as a predictive test for leprosy reactions. To improve early diagnosis and follow-up of the population at greatest risk of developing leprosy, the methodologies used in the past have yet to show a favorable cost-benefit ratio, although studies indicate that the use of the test might positively influence leprosy control programs. With simple and robust techniques, the use of PGL-I serology is viable.

Serological monitoring of previously treated lepromatous patients during a course of multiple immunotherapy treatments with heat-killed Mycobacterium leprae and BCG

Two-hundred and seventy lepromatous patients who had completed treatment received multiple treatments with heat-killed M. leprae and BCG and were monitored for changes in humoral responses to M. leprae-specific antigens. These patients were divided into four treatment groups: placebo (n = 69); BCG (n = 68); M. leprae only (n = 71); and BCG + M. leprae (n = 62). They were monitored for 15 months, receiving five inoculations for each treatment regimen. Two ELISA systems, one measuring antibodies to M. leprae-specific epitopes of the phenolic glycolipid I (NDO-ELISA) and the other of 36-kD protein antigens (INH-ELISA) were used to measure serological changes during this period of immunotherapy. We found no significant increase in serological reactivity with the different treatments, as measured by NDO-ELISA. INH-ELISA similarly showed no significant changes, with the exception of increased values in a small group 13% (36/270) which became skin test-positive during the course of the study. The NDO-ELISA results indicate that use of heat-killed M. leprae or BCG + heat-killed M. leprae did not stimulate the humoral response to the semi-synthetic PG-I antigens of M. leprae. Thus, the NDO-ELISA may be useful in monitoring the outcome of vaccine trials in which killed M. leprae or M. leprae fractions are used, since seroconversion may indicate disease, rather than a response to the vaccine material.