HLA and leprosy in Koreans

HLA antigens in 157 unrelated Koreans with leprosy have been identified and compared with 162 healthy Korean controls. The patient group consisted of 124 with lepromatous leprosy and 33 with tuberculoid leprosy. Although no significant differences were detected between the two patient groups, several antigens were found to be increased in the combined patient group compared to healthy controls. Two Class I antigens were increased: HLA-A11 (22% vs 12%) and Aw33 (27% vs 14%). Four Class II antigens were increased: HLA-DR1 (16% vs 7%), DR2 (39% vs 21%), DRw9 (14% vs 6%) and DQw1 (74% vs 55%). HLA-DR4 (28% vs 48%), DRw53 (46% vs 69%) and DQw3 (50% vs 75%) in contrast were significantly decreased in patients. Interaction of DR1, DR2, DRw9 and DQw1 as risk factors was analyzed. HLA-DR2 appeared to be the strongest risk factor. No evidence for synergy between DR1, DR2 and DRw9 was detected. DQw1 was not significantly increased in patients in the absence of DR1 and DR2, and thus it was not apparent in this study that DQw1 was an independent risk factor.     

Association of HLA antigens with differential responsiveness toMycobacterium w vaccine in multibacillary leprosy patients

Leprosy patients undergoing phase II trials in two hospitals of New Delhi, India, were HLA typed to see the association of HLA with differential responsiveness toMycobacterium w vaccine. The vaccine comprises an atypical, nonpathogenic mycobacterium,Mycobacterium w, which has cross-reactive antigens withM. leprae. Multibacillary patients who are lepromin negative are vaccinated at an interval of 3 months. Considerable improvement is evident in the patients in terms of a decline in bacterial indices and histopathological and immunological upgrading. But all the patients do not respond to the vaccine in the same manner; some are slow responders, while others are good responders. HLA-A28 and DQw3 (DQw8+9) were found to be associated with slow responsiveness, while DQw1 and DQw7 were found to be associated with a more rapid responsiveness to theM. w vaccine. However, these associations were not significant afterP correction for the number of antigens tested for each locus except for HLA-DQw3 (DQw8 and DQw9) and DQw7. DQw7, a new defined split of HLA-DQw3, seems to be associated with the responsiveness toM. w vaccine.     

HLA-DR-associated genetic control of the type of leprosy in a population from Surinam

The relationship between HLA phenotype and leprosy classification was studied in 73 unrelated patients and 92 healthy controls from a mixed Negroid-Caucasoid population originating from Surinam, South America. Heterogeneity in the distribution of HLA-DR (but not A, B, and C) was detected between tuberculoid (TT^* + BT^*) leprosy and lepromatous (BL^* + LL^*) leprosy patients (p = 0.024). This heterogeneity appeared to be caused almost exclusively by DR3. Most significantly, the frequency of DR3 was increased among polar tuberculoid (TT) leprosy patients as compared to the rest of the patients (p = 0.0003). Compared with healthy controls the frequency of DR3 was increased among TT patients p = 0.0006), unchanged in BT patients, and decreased among lepromatous (BL + LL) patients (p = 0.027). These data indicate that in this population an DR3-associated factor controls the type of the disease that develops after infection with Mycobacterium leprae.     

Potential role of B7-1 and CD28 molecules in immunosuppression in leprosy

In order to understand the mechanism of unresponsiveness towards Mycobacterium leprae antigens in leprosy, we evaluated the role of M. leprae sonicate antigens in regulating the expression of the costimulatory molecules B7-1, CD28, intercellular adhesion molecule-1 (ICAM-1), LFA-1α, LFA-1β and Mac-1 on the lymphocytes of both leprosy patients and healthy subjects. It was observed that the expression of B7-1 and CD28 was significantly decreased but the levels of ICAM-1 and LFA-1α were increased in patients with untreated borderline leprosy (BL)/lepromatous leprosy (LL) disease. No remarkable change was noticed in the case of borderline tuberculoid (BT) leprosy or treated BL/LL patients. Further, a striking finding was that lymphocytes from healthy subjects cultured with a particularly high dose of M. leprae sonicate antigens down-regulated the expression of B7-1 and CD28 molecules, but up-regulated the display of ICAM-1 and LFA-1α. Furthermore, proliferation induced by M. leprae sonicate was inhibited only by anti-B7-1 antibody. Mycobacterium leprae antigen-induced suppression of the proliferation of lymphocytes of healthy volunteers and LL patients was reversed by culturing the lymphocytes with purified protein derivative (PPD). It may be concluded from the findings in this study that down regulation of B7-1 and CD28 in BL/LL leprosy patients may be responsible for a defective T cell signalling by the B7-1/CD28 pathway caused by M. leprae antigens. This may lead to clonal inactivation of M. leprae-reactive T cells, consequently the bacilli grow without restriction in macrophages.     

Lepromatous leprosy of histoid type

Histoid leprosy is a variant of lepromatous leprosy, which develops as a result of resistance to dapsone monotherapy. Here we report two cases of lepromatous leprosy of histoid type, one with typical and another with atypical presentations.     

Association of C4B deficiency (C4B*Q0) with erythema nodosum in leprosy

A considerable number of studies have postulated significant associations between susceptibility to the different clinical manifestations of leprosy and the MHC, In this investigation, the association between the MHC class III complement proieins C2, BF, C4A and C4B and leprosy in a patient population of Southern Brazil was studied. A total of 109 non-related leprosy patients was investigated; 73 presented wilh lepromatous leprosy (LL), 46 of Ihem had the immunopathological reaction of erythema nodosum (ENL), the remaining 36 were tuberculoid, borderline and indeterminate leprosy (TIBL) patients. The control group included 172 healthy individuals matched with the patients according lo their ethnic and geographical origin, C2, BF, C4A and C4B allotypes were determined by slandard technologies including Western blots for C2 and C4 variant alleles wilh monoclonal and polyclonal antibodies. Non-expressed (‘silent’) C4 alleles in hemizygously deficient individuals were estimated semiquantitatively on the basis of the C4A and C4B isolype ratio and by the M ASC (‘minimal chi-square’) method. The results showed a significantly elevated presence of the non-expressed C4B allele (C4B*Q0) in the LL and ENL patient groups in comparison with the controls. The most signifieant difference was observed in the ENL group when compared with the controls. In addition, all patients who were homozygously C4B-deficient had ENL, and most of them had the BF*F1 allele. The comparison between LL patients with and without ENL also showed a statistically significant difference in the presence of C4B*Q0, indieating thai C4B deficiency itself is associated with EN L. The relative risk of LL patients with the C4B*Q0 allele suffering from ENL was 53 compared with LL palients without C4B*Q0, Since immune complexes (IC) are considered to be the palhogenic cause of ENL, our findings indicate thai C4B deficieney may play an important role in the abnormal immune response against Myeobaeterium leprae and in the lack of IC clearance, leading to ENL reactions. Individuals wilh this allele seem to be at a higher risk of developing pathologieal immune reactivity in lepromatous leprosy.     

Production of transforming growth factor-beta 1 (TGF-beta1) by blood monocytes from patients with different clinical forms of leprosy

In the present study, the concentration of TGF-beta1 secreted by adherent cells isolated from human peripheral blood mononuclear cells (PBMC) and either stimulated with PGL-1 or lipopolysaccharide (LPS) or left unstimulated was determined by ELISA. The cells were isolated from untreated patients with different clinical forms of leprosy and healthy individuals. The adherent cells exhibited spontaneous release of TGF-beta1 in all clinical forms of leprosy and in healthy individuals; however, lepromatous leprosy/borderline leprosy (LL/BL) patients presenting erythema nodosum leprosum (ENL) displayed significantly higher concentrations of TGF-beta1 than either the other patients studied or the controls. These high TGF-beta1 levels were consistently observed when LL/BL ENL cells were stimulated with phenolic glycolipid (PGL-1) or LPS, and even in the absence of a stimulus (P < 0.01). The most significant differences in TGF-beta1 levels were observed when comparing the results in the presence of PGL-1 from ENL with, in order of significance: tuberculoid leprosy (TT) patients (P < 0.001), LL/BL patients without ENL (P < 0.01), healthy individuals (P < 0.01) and borderline-borderline/borderline-tuberculoid (BB/BT) patients with reversal reaction (RR) (P < 0.01). The BB/BT patients produced equivalent levels of TGF-beta1 compared with LL/BL patients without ENL, for all types of stimuli (P > 0.05). In contrast, TT patients produced the lowest levels of TGF-beta1 among all the subjects studied (both patients and healthy controls), especially following PGL-1 stimulation (P < 0.001, and P < 0.05, respectively). In conjunction with our previous data regarding TGF-beta1 expression in dermal lesions, it appears that TGF-beta1 probably plays different roles in leprosy: (i) to mediate a suppressive action locally, associated with the presence of PGL-1, and (ii) to induce proinflammatory effects when secreted systemically by monocytes, thereby acting as a modulatory cytokine in the acute inflammatory reactions of ENL and associated with the Th2 immune response in multibacillary forms of leprosy.     

Utility of fine-needle aspiration cytology in the classification of leprosy

The role of fine-needle aspiration cytology (FNAC) in the diagnosis of benign skin lesions has been restricted primarily to the evaluation of bacteriologic and morphologic indices in leprosy. This study was undertaken to evaluate the efficacy of FNAC in the diagnosis and classification of lepromatous lesions. Aspirates of 94 newly diagnosed cases of leprosy were studied, and the bacterial load was determined by modified Ziehl-Neelsen (ZN) stain. A skin biopsy was taken from the same site at the same sitting. Frozen and paraffin sections stained with hematoxylin-eosin (H&E) and ZN stains were examined from the biopsy specimen. In 61 of 94 cases (64.9%), the aspirates were satisfactory. Both diagnosis and classification of leprosy were possible in 40 of these 61 cases; the rest of the aspirates showed nonspecific chronic inflammation. The 39 cases of leprosy where a biopsy was available from the same site were classified on FNAC into tuberculoid (TT and BT), lepromatous (LL and BL), and midborderline (BB) subtypes. Taking the histologic diagnosis and Ridley-Jopling classification to be the gold standard, a strong concordance in tuberculoid leprosy cases (18 of 20 cases, 90%) and in lepromatous cases (15 of 16 cases, 93.7%) was observed. Midborderline cases of leprosy posed a problem, and a correct cytohistological correlation was observed in only one of the three cases.     

Autoantibodies to cerebroside sulphate (sulphatide) in leprosy.

Sera from 40 leprosy patients were screened for autoantibodies to cerebroside sulphate (sulphatide). Anti-sulphatide IgM in groups of patients with lepromatous (LL) and borderline (BL + BB + BT), but not with tuberculoid (TT) disease, were significantly elevated above the levels found in endemic control subjects. Eight-six percent (18 out of 21; mean 1.59 OD units) of LL, 33% (four out of 12; mean 1.08 OD units) of borderline and 13% (one out of eight; mean 0.69 OD units) of tuberculoid patients had anti-sulphatide IgM in their sera above a cut-off value of 2 s.d. above the mean value (0.66 OD units) for control sera. Elevated anti-sulphatide IgG was detected in only one patient's serum, an individual with LL disease. The level of anti-sulphatide IgM was strongly correlated to expression of the TH3 idiotype, an idiotype previously defined by a human MoAb that bound Mycobacterium leprae phenolic glycolipid, Klebsiella capsular polysaccharide, polynucleotides and human tissues. The purified, TH3 MoAb was found in this study to bind sulphatide, but not cholesterol-3-sulphate or cerebroside. It is suggested that anti-sulphatide IgM is elevated in leprosy, in relation to the bacterial load. Anti-sulphatide IgM fell at the onset of erythema nodosum leprosum (ENL) reaction, consistent with the deposition of serum antibodies, and thus may play a part in pathology during periods of inflammation, particularly in multibacillary patients.     

The role of indoleamine 2, 3-dioxygenase in lepromatous leprosy immunosuppression

To elucidate further the possible role of the tryptophan, rate-limiting enzyme indoleamine 2, 3-dioxygenase (IDO) in leprosy, the distribution of IDO-positive cells and IDO activity in the skin biopsies and sera of these patients representing the entire spectrum of the disease were studied. An increased number of macrophages/dendritic cells (DC-lineage IDO(+) cells were found in lepromatous (LL) compared to tuberculoid (BT) and reversal reaction (RR) patients. IDO-positive cells showing CD68 and CD86 surface markers predominated in LL lesions, while higher levels of IDO activity were observed in the sera of LL versus BT patients. Tests revealed an increased IDO message in Mycobacterium leprae-stimulated peripheral blood mononuclear cells (PBMC) by real-time polymerase chain reaction (PCR) and increased IDO expression in M. leprae-stimulated CD14(+) cells of both healthy controls (HC) and LL patients, as evaluated via flow cytometry. Increased M. leprae-induced IDO-protein synthesis was also confirmed by Western blot. Based on our in vitro studies, it was confirmed that M. leprae up-regulated IDO expression and activity in HC and LL monocytes. Interferon (IFN)-γ synergized with M. leprae in promoting IDO expression and activity in monocytes. IDO expression induced by both IFN-γ and M. leprae was abrogated by 1-methyltryptophan (1-MT). Our data suggest that M. leprae chronic infection activates the suppressive molecule IDO which, in turn, contributes to the specific immunosuppression observed in LL leprosy.     

Demonstration of mycobacterial antigens in nerve biopsies from leprosy patients using peroxidase-antiperoxidase immunoenzyme technique

Peripheral nerve biopsies from patients with leprosy were stained with anti-Mycobacterium bovis (BCG) in a peroxidase-antiperoxidase (PAP) system to demonstrate intraneural mycobacterial antigens. Most M. leprae antigens have been shown to cross-react with BCG. Of the 30 biopsies from borderline tuberculoid (BT) patients 18 had acid-fast bacilli while 26 of them had demonstrable mycobacterial antigens in their nerves. All borderline lepromatous (BL) and lepromatous leprosy (LL) nerve biopsies had both M. leprae and mycobacterial antigens within them. Most of the antigens in the BT patients were seen to be extracellular. In BL and LL patients antigens were seen both extracellularly and intracellularly in Schwann cells and infiltrating macrophages. Mycobacterial antigens in BT nerves were always seen to be surrounded by a mononuclear cell reaction while in the BL and LL patients antigens could be seen with minimal cellular infiltrate and the neural architecture was more or less preserved. While bacilli could not be seen in BT patients who had been released from treatment for more than 4 years, mycobacterial antigens could still be seen in some patients who had been released from treatment for up to 5 years. Patients with no skin lesions but with large, painful, or tender nerves were found to have intraneural inflammation surrounding mycobacterial antigens, while those with a similar clinical picture but without tender or painful nerves showed no marked inflammation within their nerves despite the presence of mycobacterial antigens. From these findings it was concluded that immunologically mediated inflammatory response toward intraneurally located M. leprae antigens in conjunction with other host factors may be necessary for nerve damage in the BT leprosy patients. In the BL and LL patients the mechanisms of nerve damage are still unknown with certainty but local effects and immune-complex damage secondary to abundant M. leprae antigens are worth exploring. The use of immunohistological techniques should offer a new approach in the study of the immunopathology of leprosy.     

An immunotherapeutic vaccine for multibacillary leprosy

On January 30, 1998, a vaccine for leprosy based on Mycobacterium w (the code word under which this species hitherto unspecified was investigated) was launched for public use for therapeutic purposes. The vaccine has completed phase III immunotherapeutic trials as an adjunct to chemotherapy in urban and rural leprosy control centres and has received the authorization from the Drugs Controller of India for industrial manufacture. It will be made available by M/s Cadila Pharmaceuticals, Ahmedabad. As an adjunct to chemotherapy, the vaccine expediates bacterial clearance and accelerates clinical regression of lesions. It shortens significantly the period for release from treatment (RFT) of patients. It is effective in inducing a fall of bacterial index (BI) in multibacillary patients who are either nonresponders or slow responders to the standard multidrug therapy and who have persistent BI over long periods. An additional benefit of immunization with this vaccine is the conversion of >60% of LL, 71% of BL and 100% of BB patients from lepromin negativity to lepromin positivity status. A significant number of vaccinated patients showed histopathological upgrading and eventually attainment of a state of nonspecific infiltration without dermal granulomas. The vaccine was well tolerated and the incidence of Type 2 reactions and their severity was less in combined immuno cum chemotherapy group than in the group receiving only chemotherapy. This review describes the nature of the vaccine and the way it was developed.     

Evaluation of various cytokines elicited during antigen-specific recall as potential risk indicators for the differential development of leprosy

Leprosy is a dermato-neurological disease caused by Mycobacterium leprae infection that manifests across a wide range of clinical and immunological outcomes. Diagnosis is still currently based on clinical manifestations and simple tests are needed. This study investigated whether biomarkers induced by defined M. leprae proteins in 24-h whole blood assays (WBA) could discriminate active leprosy patients from at-risk contacts. Newly diagnosed, untreated paucibacillary (PB; tuberculoid leprosy/borderline tuberculoid [TT/BT]) and multibacillary (MB; borderline lepromatous/lepromatous leprosy [BL/LL]) leprosy patients, as well as healthy household contacts (HHC) of MB patients, were recruited in central western Brazil (Goiania/Goiás). Cell-based responses to the ML0276, ML1623, ML0405, ML1632, 92f, and ML1011 antigens were measured by Luminex 14-plex assays detecting eotaxin, IFNγ, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, IL-15, IL-17A, IL-23, IL-31, IP-10, and TNFα. Our data reinforce that IFNγ is currently the best indicator of the antigen-specific cellular immune response of TT/BT leprosy and demonstrate that the same antigens promote the secretion of IL-4 in blood from BL/LL leprosy patients. While none of the biomarkers tested could discriminate leprosy patients from HHC, our data indicate that, although most HHC antigen-specific responses are qualitatively similar to TT/BT patients, some HHC can respond similarly to BL/LL patients.     

Comparison of IgM, IgG and IgA responses to M.leprae specific antigens in leprosy

Antibodies of IgM, IgG and IgA classes against M.leprae specific antigens (PGL-I, ND-O-BSA, and NT-O-BSA) were determined in the sera of 80 leprosy patients (28 untreated, 34 treated lepromatous and 18 tuberculoid), 25 tuberculosis patients and 33 normal individuals of Northern Thailand. No strong distinction in reactivity could be found between the three antigens. The IgM antibody assay yielded more positive results than assays for IgG and IgA. It was found that the positivity rates of IgM antibodies to all three antigens were highest in untreated lepromatous leprosy (82%). In tuberculoid leprosy, the positivity rates of IgM, IgG and IgA to the antigens were more variable, ranging from 22 to 50 percent. Patients with tuberculosis and normal individuals did not produce IgM antibodies against the antigens. The results suggested that the determination of IgM against the three antigens is a more sensitive and specific test for active leprosy than those of IgG and IgA. The relationship between the duration of treatment and IgM antibody levels in lepromatous leprosy (LL) was studied. Untreated LL patients had significantly higher IgM and IgA antibody levels than treated patients. There was no difference in IgG antibody levels between the two groups, and the levels of both groups were higher than normal controls. Serial determination of IgM antibodies in 7 LL patients revealed that treatment was strongly associated with progressive decrease in IgM antibody levels against all three antigens.     

The involvement of dendritic cells in the cutaneous lesions associated with tuberculoid and lepromatous leprosy.

Full thickness skin biopsies were examined from 12 untreated leprosy patients and included five borderline tuberculoid (BT leprosy), five borderline lepromatous (BL leprosy) and two subpolar lepromatous leprosy cases. The non-lymphoid mononuclear cells present in the dermal infiltrates were analysed with immunohistological techniques using monoclonal antibodies (MoAb) which in normal tissues identify subpopulations of macrophage-like cells in tissue sections; RFD2 (recognizing all and monocytes/macrophages), RFD1 (recognizing interdigitating cells), NA1/34 (recognizing Langerhans cells) and RFD7 (recognizing only mature tissue macrophages). It was observed that using these MoAb no single cell type was unique to a particular state of the disease but that major differences in the proportions of these non-lymphoid mononuclear cells existed between BT leprosy and BL and LL leprosy. In BL leprosy lesions RFD2+ macrophages were the major cell type although a significant number (15-30%) of RFD1+ macrophage-like cells were also present. In contrast, in the dermal infiltrates of BT leprosy, RFD1+ cells were the predominant cell type (45-55%). The distribution of NA1/34+ Langerhans cells and the expression of Class II major histocompatibility (MHC) antigens was characteristically different in BT, BL and LL leprosy. The relationship between the presence and phenotype of cells considered to be involved in antigen presentation is discussed in relationship to the different clinical states in leprosy.     

IgG subclass distribution of antibody responses to protein and polysaccharide mycobacterial antigens in leprosy and tuberculosis patients

Immunoenzymatic assays were developed for the measurement of antibodies against mycobacterial lipoarabinomannan (LAM), a cell-free proteic extract (CFX) of Mycobacterium leprae, and the 38-kD protein antigen of M. tuberculosis. Sera from 108 leprosy patients, belonging to all clinical–immunological forms of the spectrum, and 81 patients with localized or disseminated tuberculosis (TB) were tested for antibodies of the four IgG subclasses. Standard calibration curves were used to allow comparisons between results of different isotypes and specificities. Mean concentrations of total IgG antibodies were higher in the overall leprosy population than in TB patients. In leprosy, levels of anti-CFX increased from tuberculoid toward lepromatous forms, with a clear switch from IgG1 to IgG2 subclass predominance. A similar IgG1 to IgG2 conversion was observed in anti-LAM antibodies, although total levels of anti-LAM were similar in patients with tuberculoid and lepromatous forms. In TB, antibodies against polysaccharide and protein antigens were both predominantly of IgG1 subclass, whatever the patient's clinical status, although lower in disseminated forms, probably due to concomitant HIV infection. A hypergammaglobulinaemia was also found in most leprosy and TB patients. In TB this was due to increased IgG1 and IgG3, especially in HIV co-infected patients. Based on the current knowledge of the influence of T cell-secreted cytokines on human immunoglobulin isotype expression, these results do not fit with a putative role of Th1 (such as found in TB and tuberculoid leprosy (TT)) and Th2 (such as found in leprosy lepromatous (LL) leprosy) environment in the isotypy of antibody responses in mycobacterial infections. Nor do variations of isotypy according to pathological conditions seem to be related to the biochemical nature of antigens, since antibodies to LAM and protein antigens had comparable evolutions of their subclass distribution. Other factors are to be investigated in order to understand better the significance and possible roles of antibodies in mycobacterial diseases.     

Expression of a common idiotype PR4 in the sera of patients with leprosy.

The sera of 187 patients from across the leprosy spectrum were screened for the expression of the PR4 idiotype, which was first identified on a human hybridoma-derived monoclonal antibody from a patient with leprosy and found to react with the Mycobacterium leprae phenolic glycolipid and a variety of polynucleotides. Sixty per cent (51 out of 85) of patients with lepromatous leprosy (LL), 66% (33 out of 49) with borderline lepromatous (BL) disease, 47% (14 out of 30) with borderline tuberculoid (BT) leprosy, and 56% (13 out of 23) of tuberculoid (TT) patients were found to have significantly elevated titres of the PR4 idiotype in their sera compared with endemic controls, irrespective of the presence or absence of endemic malaria. Sera from 52 patients with tuberculosis were also screened as a control for mycobacterial infection. The PR4 idiotype was significantly elevated in 37% (19 out of 52) of these patients. No correlation between idiotype and serum immunoglobulins IgG and IgM was found, indicating that the concentrations of idiotype levels in sera were not merely a reflection of changes in serum immunoglobulin levels. It is hypothesized that the expression of the PR4 idiotype is due to certain germline genes preferentially expressed rather than being the result of polyclonal B cell activation.     

Detection of antibodies to human nerve antigens in sera from leprosy patients by ELISA.

Anti-neural antibodies have been implicated to play a role in the pathogenesis of nerve damage in leprosy patients. To find the relationship between anti-neural antibodies and clinical findings, we attempted to detect antibodies against neurofilament-enriched proteins by ELISA in sera from leprosy patients. Of 289 sera from leprosy patients, 74 (25.6%) had significant anti-neural antibodies; in contrast, 1 (5.0%) of 20 tuberculosis patients and 11 (7.1%) of 154 controls were seroreactive to nerve antigen. When clinical types were considered, a significant level of anti-neural IgG antibodies was detectable in 53 (30.1%) of 176 sera from lepromatous patients compared with 21 (18.6%) of 113 sera from tuberculoid patients, indicating that lepromatous patients were more likely to be seropositive to nerve antigens in ELISA. Some of the ELISA-reactive sera showed antibody reactivity with 38-kD, 40-kD and 43-kD nerve antigens in Western blotting analysis. There was no apparent correlation between seroreactivity to nerve antigens and bacterial load in leprosy patients. Although there was no statistical significance, anti-neural antibodies were detectable more often among the patients on chemotherapy than the untreated and among the patients with erythema nodosum leprosum than without. The results, therefore, suggest that anti-neural antibodies are elicited during the course of leprosy and may be associated with the extensiveness of nerve involvement in the patients.     

In vitro effect of interleukin-2 on proliferative responses of peripheral blood T cells from leprosy patients.

Because of the important role played by interleukin-2(IL-2) in T cell growth and differentiation, we investigated the effect of exogenous IL-2 on the proliferative response of peripheral blood mononuclear cells(PBMCs) from 77 leprosy patients. The proliferative responses of PBMCs from lepromatous leprosy(LL) or borderline lepromatous leprosy(BL) patients to M. leprae were significantly lower(cpm 6,051 +/- 803 for LL type; 4,951 +/- 2,529 for BL type) than those from tuberculoid leprosy(TT) or borderline tuberculoid leprosy(BT) patients (28,853 +/- 28,916 for TT type; 15,884 +/- 334 for BT type). To investigate the effect of exogenous IL-2, purified IL-2 was added at the start of culture at 100 unit/ml. There was an apparent increase in 3H-thymidine incorporation of M. leprae-stimulated PBMCs(18,723 +/- 6,503) in the presence of IL-2 compared to the results without IL-2(6,051 +/- 803) in LL patients. Twenty nine out of 33 LL patients belonged to the responders to IL-2 and four patients were nonresponders. Therefore we conclude that the defective cell mediated immune response in LL patients may result from diminished production of IL-2, but we can not exclude the possibility of diminished expression of the IL-2 receptor. And we suggest that the immunologic heterogeneous response of an individual to M. leprae is important to the pathogenesis of clinical disease in the same LL patients.     

Accessory cell heterogeneity in lepromatous leprosy; dendritic cells and not monocytes support T cell responses.

Dendritic cell (DC)-enriched cell populations from anergic lepromatous leprosy (LL) patients were found to be several-hundred-fold more efficient than monocytes (MO) in promoting antigen-induced T cell responses in autologous accessory + T cell cultures. Whereas, the use of autologous monocytes over a wide concentration range failed to stimulate Mycobacterium leprae-induced T cell proliferation, DC at concentrations as low as 0.1% induced significant proliferation in 9/15 and interferon gamma production in 14/15 LL patients. Four of the LL patients who failed to show proliferation were, however, able to secrete interferon gamma in the same T cell + DC co-cultures. DC were able to present particulate leprae antigens to autologous T cells. This preference for DC as an accessory cell was not shown when the cross-reacting antigen PPD was used in parallel co-cultures. Though tuberculoid leprosy patients showed some improvement in T cell proliferation with DC as compared to MO constituted co-cultures, this was not statistically significant. These results suggest that there is a heterogeneity in accessory cell requirement across the leprosy spectrum and that many lepromatous patients possess M. leprae-reactive functional T cells.