The cellular architecture of the antimicrobial response network in human leprosy granulomas.

Granulomas are complex cellular structures composed predominantly of macrophages and lymphocytes that function to contain and kill invading pathogens. Here, we investigated the single-cell phenotypes associated with antimicrobial responses in human leprosy granulomas by applying single-cell and spatial sequencing to leprosy biopsy specimens. We focused on reversal reactions (RRs), a dynamic process whereby some patients with disseminated lepromatous leprosy (L-lep) transition toward self-limiting tuberculoid leprosy (T-lep), mounting effective antimicrobial responses. We identified a set of genes encoding proteins involved in antimicrobial responses that are differentially expressed in RR versus L-lep lesions and regulated by interferon-γ and interleukin-1ß. By integrating the spatial coordinates of the key cell types and antimicrobial gene expression in RR and T-lep lesions, we constructed a map revealing the organized architecture of granulomas depicting compositional and functional layers by which macrophages, T cells, keratinocytes and fibroblasts can each contribute to the antimicrobial response.

Fate of T Cells and their Secretory Proteins During the Progression of Leprosy.

Leprosy is an infectious disease caused by non-cultivable bacteria Mycobacterium leprae. Ridley and Jopling classified the disease into five polar forms, Tuberculoid (TT) and Lepromatous (LL), in between two forms of the disease Borderline tuberculoid (BT), Borderline (BB) and Borderline lepromatous (BL) are laid. The tuberculoid type (BT/TT) leprosy patients show good recall of cellmediated immune (CMI) response and Th1 type of immune response, while lepromatous leprosy (LL) patients show defect in cell-mediated immunity to the causative agent and Th2 type of immune response. Due to distinct clinical and immunological spectra of the disease, leprosy attracted immunologists to consider an ideal model for the study of deregulations of various immune reactions. Recent studies show that Tregs, Th3 (TGF-ß, IL-10), IL-35 producing Treg immune response associated with the immune suppressive environment, survival of bugs. IL-17 producing Th17 immune response associated with tuberculoid leprosy and play protective role. γδ T cells also increased from tuberculoid to lepromatous pole of leprosy. In this review, we will discuss the role of various subtypes of T-cell and their cytokines in the pathogenesis of leprosy.

Keratoderma-like T cell dyscrasia: A report of 13 cases and its distinction from mycosis fungoides palmaris et plantaris.

BACKGROUND: Atypical epitheliotropic T cell lymphocytic infiltrates are commonly encountered in routine and consultative dermatopathology practices and typically do not represent mycosis fungoides. Other conditions can mimic certain light microscopic and phenotypic findings encountered in mycosis fungoides, comprising a diverse spectrum of conditions including the lymphomatoid drug reaction, collagen vascular disease, viral hypersensitivity reactions and cutaneous T cell dyscrasia. AIMS: To examine biopsies obtained from cutaneous T cell dyscrasia localized to the palms and soles and to evaluate whether it exhibits a morphologic and pathogenetic continuum with mycosis fungoides plantaris et palmaris. METHODS: We examined 13 biopsies showing an epidermotropic superficial lymphocytic infiltrate from thirteen patients who presented with a palmar and/or plantar keratoderma without other sites of cutaneous involvement. Conventional light microscopy, immunophenotyping and clonality studies were carried out. The clinical features were recorded. RESULTS: Biopsies showed a variably dense, superficial, angiocentric CD4 or CD8 dominant lymphocytic infiltrate accompanied by a non-destructive pattern of epidermotropism. Low-grade cerebriform atypia along with variable diminution in the expression of CD7 and CD62L was noted. In three cases, statins were suspected to be the cause. Due to lack of familiarity with the entity, treatment interventions were inconsistent and not aggressively pursued. There was no evidence of disease progression to mycosis fungoides in any case. LIMITATIONS: The limitations of this study include the lack of long-term follow up and information on the nature of the therapeutic interventions and responses to treatment. CONCLUSION: The spectrum of cutaneous lymphoid dyscrasias should be expanded to include cases manifesting as palmo-plantar keratoderma. These cases are to be distinguished from mycosis fungoides palmaris et plantaris. As with other forms of cutaneous lymphoid dyscrasia, the lesions tend to be persistent. The course however, is indolent in most cases.

Mycobacterial r32-kDa antigen-specific T-cell responses correlate with successful treatment and a heightened anti-microbial response in human leprosy patients.

BACKGROUND: Immunological characterization of mycobacterial peptides may help not only in the preparation of a vaccine for leprosy but also in developing in vitro T-cell assays that could perhaps be used as an in vitro correlate for treatment outcome. The main goal of this study was to evaluate the use of Mycobacterium bovis recombinant 32-kDa protein (r32-kDa) antigen-stimulated T-cell assay as a surrogate marker for treatment outcome and monitor vitamin D receptor (VDR)-mediated anti-microbial responses during multidrug therapy (MDT) in leprosy. METHODS: Newly diagnosed tuberculoid and lepromatous leprosy patients were enrolled and followed up during their course of MDT at 6 and 12 months. IFN-γ, IL-10, IL-17 and IL-23 levels in culture supernatants and expression of VDR, TLR2, LL37 and DEFB in r32-kDa-stimulated PBMCs were measured. Controls comprised household contacts (HHCs) and healthy endemic subjects (HCs). RESULTS: Significant differences were observed in the levels of IFN-γ, IL-17, IL-23, VDR and anti-microbial peptides LL37 and DEFB after treatment and when compared with that of HHCs and HCs, respectively. CONCLUSIONS: These findings suggest that responses to r32-kDa antigen reflect an improved immunological and anti-microbial response in leprosy patients during therapy, thereby indicating its potential use as an immune correlate in the treatment of leprosy patients.

The role of Schwann cells, T cells and Mycobacterium leprae in the immunopathogenesis of nerve damage in leprosy.

Damage to peripheral nerves is the major complication of reversal (type I) reactions in leprosy. The underlying mechanism of nerve damage remains largely unresolved; however, an important role for type-1 T cells has been suggested. Mycobacterium leprae has a remarkable tropism for the Schwann cells that surround peripheral axons. Because reversal reactions in leprosy are often accompanied by severe and irreversible nerve destruction, and are associated with increased cellular immune reactivity against M. leprae, a likely immunopathogenic mechanism of damage to Schwann cells and peripheral nerves in leprosy is that infected Schwann cells process and present antigens of M. leprae to antigen-specific, inflammatory, type-1 T cells, and that these T cells subsequently damage and lyse infected Schwann cells. Previous animal studies with CD8+ T cells revealed evidence for the existence of such a mechanism. A similar role has been suggested for CD4+ T cells. These latter cells may be more important in causing nerve damage in vivo, given the predilection of M. leprae for Schwann cells, and the dominant role of CD4+, serine esterase+ Th1 cells in the lesions of leprosy. Antagonism of the molecular interactions among M. leprae, Schwann cells and inflammatory T cells may therefore provide a rational strategy for prevention of damage of Schwann cell and nerves in leprosy.

T lymphocyte subpopulations in leprosy patients and their relation with circulating immune complexes.

The possible relationship between circulating immune complexes (CIC) and peripheral T lymphocyte populations was studied in thirteen active multibacillary leprosy (10 lepromatous--LL--and 3 borderline lepromatous--BL--) and 19 matched controls. Theophylline-resistant T cells (The-R, a lymphocyte subpopulation displaying helper activity on B cells) and total T cells were assessed by means of the E rosette technique, with and without previous theophylline incubation, 1h 37 degrees C, respectively. CIC were quantified by 125I-C1q binding test. Although leprosy patients showed a statistical non significant light depression in total T cells the remarkable variability in circulating levels of The-R T cells enabled us to separate them into two well delineated groups (in relation to this variable p less than 0.001) with no difference in age, sex and bacteriologic state: a) leprosy patients with The-R T cells proportionally conserved (6LL and 2BL); b) leprosy patients with The-R T cells proportionally depressed (4LL and 1BL). Patients belonging to the latter group showed the highest statistically significant levels of CIC. Even though we do not discard an unknown factor being responsible for our findings, we believe that this inverse relationship between elevated CIC and depressed The-R circulating T cells might be representing a lower helper activity on antibody synthesis intending to reduce its excessive production.

Suppress of the increase in free cytosolic calcium during the inhibition of T-cell activation by an autoantibody present in the serum of leprosy patients.

A serum factor, believed to be an IgG autoantibody, in certain patients with lepromatous leprosy inhibits the proliferation of mitogen-stimulated lymphocytes. To investigate which stage of the cell cycle was inhibited, we examined the effect of these sera on the kinetics of lymphocyte activation induced by several mitogenic agents: phytohaemagglutinin (PHA), the calcium ionophore A23187, the phorbol ester phorbol myristate acetate (PMA) and purified protein derivative of BCG (PPD). Seven out of 54 sera tested were found to inhibit PHA-stimulated proliferation. Inhibitory sera and to a lesser extent serum IgG from leprosy patients were capable of suppressing the increase in free cytosolic calcium normally observed immediately after PHA stimulation. Subsequent stages of the cell cycle, increase in cell size, the expression of the IL-2 receptor and increase in DNA were also suppressed. The inhibitory sera was not toxic and, if addition of the sera was delayed, would not inhibit lymphocytes that had already entered the cell cycle. Using mitogenic agents which act intracellularly, the normal early increase in cell size with A23187- and PMA-stimulated lymphocytes was not affected by inhibitory leprosy sera or serum IgG, but all subsequent steps in the cell cycle were suppressed; although the inhibition of proliferation in PMA-stimulated cultures was incomplete. The mechanism of action of the inhibitory sera and derived IgG, although acting through a cell surface antigen, appears to interfere with a fundamental process in activation since the effect was seen with all of the diverse stimuli examined in this study.

The reconstitution of cell-mediated immunity in the cutaneous lesions of lepromatous leprosy by recombinant interleukin 2.

Human rIL-2 (10-30 micrograms) was injected intradermally into the skin of patients with lepromatous leprosy with high bacillary loads. All patients responded to the lymphokine with local areas of induration that peaked at 24 h and persisted for 4-7 d irrespective of whether the site was "normal skin" or a nodular lesion. Within 24 h there was an extensive emigration of T cells and monocytes into the site. The percentage of the dermis infiltrated by mononuclear cells increased by more than sevenfold, peaking at 4 d and persisting for greater than 15 d. Both CD4+ and CD8+ T cells entered the site. T cells of CD4+ phenotype predominated at 2-7 d but by 11 d, CD8+ cells were predominant. Considerable numbers of T6+ Langerhans' cells appeared in the dermis by 72 h and persisted for 3 wk. By 4 d the thickness of the overlying epidermis had increased twofold, and keratinocytes were expressing MHC class II antigen and the IFN-gamma-induced peptide IP-10. Starting at 48 h, there was an extensive destruction of mononuclear phagocytes that contained structurally intact or fragmented M. leprae observed at the electron microscope level. The organisms, either free or contained within endocytic vacuoles, were discharged into the extracellular space and then reingested by blood-borne monocytes. This was followed by marked reductions in the number of acid-fast organisms in the injected site, evident as early as 4-7 d and more marked at 2-3 wk after injection. 13 of 15 patients exhibited a disposal of acid-fast bacilli ranging from 5- to 1,000-fold with a mean value of approximately 100-fold. The administration of IL-2 leads to the generation of an effective cell-mediated immune response, recapitulating an antigen-driven event and leading to striking local reductions in M. leprae. In comparison with the purified protein derivative of tuberculin reaction, bacilli are cleared more promptly, although emigratory cells persist for a shorter time.

Comparison of the characteristics of infiltrates in skin and nerve granulomas of leprosy.

The characteristics of infiltrates in the dermal and neural granulomas from the same leprosy patients were compared by preparing a single cell suspension. Skin and nerve biopsies from 10 patients, 5 with tuberculoid and 5 with lepromatous leprosy were analysed. The granulomas contained lymphocytes and macrophages. Lymphocytes were the predominant infiltrating cells in the tuberculoid dermal and neural granulomas. A high proportion of lymphocytes in both the skin and nerve granulomas in these cases were activated T cells as they formed rosettes with sheep erythrocytes and expressed HLA-DR antigens. In contrast, lepromatous dermal and neural granulomas contained very few of these lymphocytes. Dermal and neural granulomas from both the types of leprosy contained mature macrophages as they were esterase positive, did not exhibit peroxidase activity and expressed HLA-DR antigens. These macrophages did not possess C3 surface receptors either. These findings suggest that the infiltrates in the skin and nerve granulomas of a given type of leprosy have similar characteristics.

Isolation and characterization of cells in granulomas of nerves of leprosy patients.

Single cell suspension from the granulomas in nerves of leprosy patients were prepared for an in vitro study of the properties of infiltrating cells. Nerve biopsies from 17 patients with tuberculoid (n = 9) and lepromatous (n = 8) leprosy cases were analysed. The granulomas were found to contain lymphocytes and macrophages. Lymphocytes were the predominant infiltrating cells in the tuberculoid nerves. In contrast, lepromatous nerves contained very few of these cells. The majority of lymphocytes in tuberculoid granulomas were activated T cells as they formed rosettes with sheep erythrocytes, exhibited esterase dots in the cytoplasm and expressed HLA-DR antigens. A small proportion of the lymphocytes also formed rosettes with EAC. Most macrophages from both the granulomas were mature macrophages as they were esterase positive, did not exhibit peroxidase activity and expressed HLA-DR antigens. The macrophages did not possess C3 surface receptors.

Efficacy of a cell-mediated reaction to the purified protein derivative of tuberculin in the disposal of Mycobacterium leprae from human skin.

The purpose of this study was to evaluate the effects of a delayed-type cell-mediated immune response to Mycobacterium tuberculosis antigen on the Mycobacterium leprae load in the skin of leprosy patients. Twelve patients with the lepromatous form of leprosy have been injected intradermally with 5 units of the purified protein derivative of tuberculin (PPD). Ten individuals responded with areas of induration ranging from 12 to 21 mm in diameter, and two were unresponsive (less than 10 mm). Twenty-one days thereafter, the injected and control sites were biopsied, and the histology, number of acid-fast bacilli, nature and phenotype of the emigrant cells, and ultrastructural characteristics of the lesions were evaluated. Eight of the 10 responding patients showed reductions in the number of acid-fast bacilli by factors ranging from 5 to 10,000. Two responders and both nonresponders exhibited no discernible decline in the number of organisms. The reduction in bacillary load was correlated with an intense mononuclear cell infiltrate, the maintenance of a high CD4+ T-cell/CD8+ T-cell ratio, the formation of granulomata, and the extensive destruction of previously parasitized macrophages.

[Characterization of experimental infection with Mycobacterium lepraemurium in 2 strains of mice]. / Caracterización de la infección experimental con Mycobacterium lepraemurium en dos cepas de ratones.

A model of experimental leprosy in two strains of mice, namely CBA/J and CBi, has been developed based on: 1) the histological examination of a granuloma in the hind foot pad 200 days after inoculation of 0.30 microliter of Mycobacterium lepraemurium (6 x 10(8) MLm/ml); 2) the assessment of T lymphocytes in the granuloma identified by the alpha-naphthyl acetate method for esterase, and c) dissemination of the infection. The histological findings in the low resistance CBA/J strain included positive acid fast bacilli vacuolated cells, without lymphocytic infiltration, scarce number of T lymphocytes and a generalized and important dissemination, similarly to the one observed in human lepromatous leprosy. The histological findings in the hind foot pad granuloma of 30-40 per cent of the medium to high resistance CBi strain, consisted of vacuolated cells and lymphocytic infiltration, a large number of T cells and a scarce dissemination, similar to the human borderline leprosy. Both strains present a different susceptibility to a unique challenge with the mycobacterium which could be useful to disentangle the immunogenetic components involved, by means of appropriate selection and crosses. Furthermore, it could be of interest to perform immunoprotection assays in CBi mice, which might have some bearing on the development of a vaccine in human leprosy.

Local and systemic effects of intradermal recombinant interferon-gamma in patients with lepromatous leprosy.

Evidence that interferon-gamma may be a physiologic macrophage-activating factor, and that macrophage activation may be defective in lepromatous leprosy, led us to test the effects of intradermal injection of low doses of recombinant interferon-gamma in six patients with this disease. Interferon-gamma, 1 or 10 micrograms, was administered daily by jet gun for three days into a single cutaneous lesion. A biopsy specimen was taken from the injection site on the sixth study day and compared with specimens obtained previously from a site where no injection had been made or where excipient alone had been injected in the same way as the interferon. Interferon-gamma elicited local effects similar to certain features of delayed-type hypersensitivity reactions or tuberculoid leprosy, including induration, T-cell and monocyte infiltration, keratinocyte proliferation, diminution of epidermal Langerhans cells, and dermal and epidermal cell HLA-DR (Ia) antigen expression. At some of the sites of interferon-gamma injection, there was also an apparent decrease in acid-fast bacilli. Before treatment, monocytes from patients with lepromatous leprosy released 48 percent as much hydrogen peroxide as did monocytes from controls in response to phorbol myristate acetate, and 36 percent as much as those from controls in response to Mycobacterium leprae. When recombinant interferon-gamma was injected, these responses became normal. No toxic effects were observed. These observations suggest that interferon-gamma can mediate certain manifestations of delayed-type hypersensitivity or cell-mediated immunity in vivo, and that recombinant interferon-gamma should be tested for possible therapeutic effects in certain nonviral infectious diseases.

Tissue and blood T-lymphocyte subpopulations in erythema nodosum leprosum.

To study T lymphocytes in erythema nodosum leprosum (ENL), monoclonal antibodies were used to identify T-lymphocyte subpopulations in the blood and skin lesions of patients with ENL and patients with nonreactional lepromatous leprosy. The blood of nonreactional lepromatous patients had a lymphopenia and a proportionate reduction in pan T cells, helper-inducer, and suppressor-cytotoxic subsets, but a normal helper-suppressor ratio, as compared with controls. Patients with ENL did not differ significantly from the controls. In skin lesions, an admixture of helper and suppressor phenotypes among foamy histiocytes was found. The ENL tissue had more numerous cells of the helper-inducer phenotype and fewer of the suppressor-cytotoxic phenotype, as compared with nonreaction lepromatous tissues. In 22 patients with simultaneous examination of tissue and blood T-cell subsets, there was no correlation between tissue and blood helper-suppressor ratios, indicating that some sort of selection process brings lymphocytes into tissues from peripheral blood.

Immunoperoxidase techniques applied to dermatopathology.

Immunoperoxidase techniques provide the pathologist with the capability for staining a wide range of antigens in tissue sections. More than 100 different antigens have been successfully demonstrated in fixed paraffin sections; other antigens can only be visualized in frozen sections. This latter group particularly includes lymphocyte surface antigens detectable by monoclonal antibodies. This review describes the current state of the art and provides several illustrations of the use of monoclonal antibodies for the identification of T-lymphocyte phenotypes in frozen section from cases of leprosy, mycosis fungoides, halo nevus, Kaposi's sarcoma, lichen planus and atopic dermatitis. Technical details and potential applications are discussed. The growing availability of commercial immunostaining kits makes these techniques more accessible to the surgical pathologist; indeed a whole new range of truly specific, special stains are available, as pathologists we must simply learn to use them.

The histopathology of the spleen from a patient with lepromatous leprosy.

The histopathology of the spleen from a young man with diffuse non-nodular lepromatous leprosy is reported. As judged by this case, other case reports, and necropsy series, involvement of the spleen in lepromatous leprosy is characterized by aggregations of large vacuolated histiocytes, containing individual bacilli and globi, in both the red and white pulp. In the white pulp the histiocytes localize about the arterioles. Findings in the present case, which may represent a comparatively early change, include numerous, small germinal centers containing nonaggregated large, vacuolated histiocytes with intracellular bacilli.

Numerical changes in T cell subsets (T gamma and T mu) in leprosy patients.

Eighty-six leprosy patients (49 active lepromatous, 24 inactive lepromatous 7 borderline, and 6 tuberculoid) and nine healthy controls were examined for numerical changes in T cell subsets (T gamma and T mu), and complement levels in peripheral blood to determine the roles of T cell subsets and complement in the etiology of leprosy. The percentage and number of T gamma and T mu showed no significant differences among the different clinical groups, but 4 out of 49 active lepromatous, 3 out of 24 inactive lepromatous and 3 out of 7 borderline cases showed a high prcentage of T gamma cells. Serum concentrations of C4, C3c, and C3 activator, an important factor in the alternative pathway of complement activation, were not significantly different among the groups. However, C3 activator and C3c concentrations were significantly high in active lepromatous patients complicated by an immune complex disease called "erythema nodosum leprosum" (ENL) compared with ENL-free active lepromatous leprosy.