Sequential monitoring of 724 sera for antibodies to a neoantigen based on phenolic glycolipid-I (PGL-I) and native lipoarabinomannan (LAM) in 90 leprosy patients undergoing therapy in San Francisco was conducted. Untreated lepromatous patients frequently (91%) had significant antibodies to both moieties. Antibodies were less frequently found in tuberculoid patients (74% to neoantigen and 37% to LAM). In the first 3 years of treatment, average serum antibodies to both moieties fell significantly. Antibodies to LAM fell during each of the first 4 years of therapy, but decreasing antibody levels to the PGL-I neoantigen did not appear to fall consistently after the third year of treatment. A wide variation in the rate of fall of serum antibodies was noted. Sequential changes in the amounts of serum antibodies to the neoantigen and LAM in general paralleled one another but were at times discrepant. Both in San Francisco and Malaysia, skin-smear negative, long-term treated, lepromatous leprosy patients frequently harbored significant antibodies to both PGL-I and LAM.
The proliferative responses of peripheral blood mononuclear cells (PBMC) to Mycobacterium leprae and BCG were studied in two groups of leprosy patients: a group of 8 lepromatous patients who had been on treatment for more than 20 years (TLL) and a group of 8 untreated lepromatous leprosy patients (ULL). The mean response to M. leprae of the TLL group was 6195 cpm with 5 of the 8 patients responding positively. The mean response to M. leprae of the ULL group was 617 cpm, with only 1 patient showing a positive response. The corresponding proliferative responses to BCG were 19,908 cpm in the TLL group and 7908 in the ULL group. Thirteen M. leprae reactive clones were established from 2 TLL patients and 5 M. leprae reactive clones were established from 2 tuberculoid leprosy patients. Seven of these clones, 4 from the TLL patients and 3 from the tuberculoid (TT) patients could be studied further. Three of the TLL clones responded specifically to M. leprae, while one of the clones exhibited a broad cross-reactivity to other mycobacteria. All of these clones were of the CD4+CD8- phenotype. Our findings suggest that responsiveness to M. leprae can be detected in vitro in a proportion of LL patients who have undergone prolonged chemotherapy, and that this response involves M. leprae reactive CD8+CD8- T cells, of which some appear to be specific to M. leprae.
Leprosy continues to pose a significant challenge to public health, particularly in certain global regions. Accurate diagnosis and understanding of the disease's etiology are crucial for effective management and prevention. This study aimed to explore the contribution of Natural resistance-associated macrophage protein 1 (NRAMP1) and its genetic variations, as well as the levels of anti-PGL-1 antibodies, to the pathology of multibacillary leprosy in affected individuals and their household contacts. The study included 23 multibacillary leprosy patients and 28 household contacts. NRAMP1 protein expression and anti-PGL-1 IgG and IgM levels were measured using PCR and ELISA techniques, respectively. Genotypic variants of the NRAMP1 gene were also examined. Statistical analyses, including Mann-Whitney tests and univariate logistic regression, were employed to evaluate the data. Significant differences were observed in NRAMP1 protein expression and IgG and IgM levels between the patient and household contact groups. The study also highlighted the role of the NRAMP1 gene and its D543N and 3'UTR polymorphisms in leprosy susceptibility. No significant differences were observed in the genotype variants of INT4 between the two groups. These findings emphasize the potential of integrating PCR technology with serological tests to enhance diagnostic precision in leprosy. They also suggest the need for further research to clarify the role of NRAMP1 and its polymorphisms in leprosy susceptibility and resistance.