R L Modlin

Determination of the cytokine profile in American cutaneous leishmaniasis using the polymerase chain reaction.

The lymphokine profiles were determined in the skin lesions of the three distinct clinical forms of American cutaneous leishmaniasis (ACL), using a reverse transcriptase polymerase chain reaction (RT‐PCR) and primers for various lymphokines. The message for interferon‐gamma (IFN‐y). tumour necrosis factor‐beta (TNF–β) and IL‐8 was expressed in the three clinical forms of ACL. IL‐lβ inRNA was expressed in most localized (LCL) and mucoeutaneous (MCL) leishmaniasis. but in only few of the diffuse cutaneous leishmaniasis (DCL). IL‐2 mRNA was detected in about half of the lesions, with more prominent values for MCL. IL‐4 mRNA was present in most lesions from the three clinical forms, but markedly increased in DCL. IL‐5 and IL‐10 mRNAs were expressed in all MCL and in half of the DCL lesions and weakly expressed in LCL lesions. IL‐10 mRNA was more abundant in MCL lesions. In contrast. IL‐6 and TNF‐s mRNAs were expressed in a Iarge number of LCL. In MCL, IL‐6 mRNA was expressed in most cases and TNF–α mRNA in all the cases. In DCL. 11,–6 mRNA was absent and TNF–α mRNA was weakly expressed. These results suggest that most T cells present in the MCL and DCL lesions secrete a mixture of type 1 and type 2 cytokine patterns, but in DCL granulomas type 2 cytokines predominate. In LCL the cytokine patterns show a mixture of type l and type o with a preponderance of IFN–γ over IL‐4, and low levels of IL‐5 and IL‐10. The Iack of IL‐6 and TNF–α mRNAs, and the low expression of IL‐lβ in DCL lesions suggest a defect in the anligcn‐processing cells that may account for the state of unrcsponsiveness in these patients.

T lymphocyte subsets in the skin lesions of patients with leprosy

Lymphocyte subsets in the tissues of fourteen patients with leprosy were studied using monoclonal antibodies and a modified immunoperoxidase technic. Two immunohistologic patterns were observed. In tuberculoid leprosy, helper-inducer cells were present among the aggregates of mononuclear phagocytes (epithelioid cells), but the suppressor-cytotoxic cells were predominantly in the lymphocytic mantle surrounding the epithelioid cell aggregates. In reversal reaction and lepromatous tissues, the helper-inducer and the suppressor-cytotoxic cells were both distributed among the mononuclear phagocytes (histiocytes). In tuberculoid specimens the Langerhans cells of the epidermis were increased in number as compared to lepromatous and normal tissues. The technic used appears to be of value in studying some of the cellular components of the immune response in situ.

Kaposi's sarcoma in homosexual men: an immunohistochemical study.

A recent outbreak of disseminated Kaposis sarcoma has been recognized in homosexual men in New York, San Francisco, and Los Angeles. Biopsy specimens of skin lesions were obtained from nine of these homosexual men in Los Angeles and San Francisco. T lymphocyte subset antigens, factor VIII-related antigen, and HLA-Dr antigen were evaluated in situ in frozen sections using immunoperoxidase technics. Factor VIII-related antigen and HLA-Dr antigen were present on tumor cells, supporting a vascular endothelial origin of this neoplasm. Langerhans cells and T lymphocytes were present in numbers similar to that of normal skin in skin specimens from seven patients with Kaposis sarcoma with visceral dissemination, but were increased in specimens from two patients with only cutaneous involvement.

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 lie 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 fro/en section from cases of leprosy, mycosis fungoides, halo nevus, Kaposis sarcoma, lichen planus and atopic dermatitis. Technical details and potential applications arc 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.

Immunopathology of leprosy granulomas.

Lymphocytes T dans les lesions lepreuses. Etude anatomopathologique, sous populations cellulaires de lymphocytes T. Etude de lepiderme, modeles experimentaux. Extraction des lymphocytes a partir des lesions, fonctions des lymphocytes derives des tissus

In situ detection of amastigotes in American cutaneous leishmaniasis, using monoclonal antibodies

Using an immunoperoxidase technique we have applied monoclonal antibodies against American Leishmania for the detection of amastigotes in biopsies from cutaneous leishmaniasis patients. The immunocytochemical procedure was notably superior to conventional histological staining in terms of the visualization and definition of the amastigotes. This technique could eventually prove to be of value in epidemiological studies, and possibly have prognostic importance, by allowing the in situ characterization of the species of infecting organism.

Lepromin-induced suppressor cells in lepromatous leprosy

The presence or absence of suppressor cells in leprosy patients was investigated by measuring peripheral blood lepromin-induced suppression of the Con A response. Significant suppressor activity was measured in 15 of 15 untreated or recently treated patients with lepromatous leprosy and 3 of 5 patients with borderline lepromatous leprosy. In addition, in patients with lepromatous leprosy, suppressor cell activity was found in 10 of 14 patients that had been under treatment for more than 1 year but in only 2 of 27 patients who had active or thalidomide controlled erythema nodosum leprosum. Suppression was observed in only 5 of 29 tuberculoid leprosy patients, 1 of 6 patient contacts, and 0 of 11 normal controls. The differences between the lepromatous or borderline lepromatous group as compared with the tuberculoid group were statistically significant (P less than 0.001). Our findings confirm the presence of lepromin-triggered suppressor cells in the peripheral blood of patients with lepromatous leprosy. These suppressor cells may contribute to the selective unresponsiveness of lepromatous patients to the antigens of Mycobacterium leprae.

Mechanisms of Immunological Unresponsiveness in the Spectra of Leprosy and Leishmaniasis

Leprosy and cutaneous leishmaniasis share a number of important characteristics1,2. They are both chronic granulomatous diseases; both affect the skin and both present a spectrum of clinical manifestations. In the case of leprosy, there is a remarkable correlation between the clinical and histopathological spectrum, and cell-mediated immune responsiveness to antigens of M. leprae. At the tuberculoid pole, patients have few lesions which contain rare organisms and are able to mount strong T-cell-mediated immune responses to M. leprae antigens in vitro and in vivo. In contrast, at the lepromatous end of the spectrum, patients have disseminated skin lesions containing large numbers of acid-fast bacilli and are selectively unresponsive to antigens of M. leprae. In American cutaneous leishmaniasis, the spectrum is somewhat less well defined, more variable clinically and less predictable at the histopathologic level. The disease ranges from a single defined lesion containing few amastigotes in localized cutaneous leishmaniasis (LCL) to diffuse cutaneous leishmaniasis (DCL) which, like lepromatous leprosy, is characterized by disseminated granulomata containing macrophages laden with amastigotes and immune unresponsiveness to leishmanial antigens. There are other clinical forms of cutaneous leishmaniasis including the highly destructive mucocutaneous (espundia) form, and a verrucous form, the pathogenesis of which are not entirely predictable from histopathology and molecular immunological data. In addition, in different parts of the world systemic forms of visceral leishmaniasis (kala-azar) occur in Asia, and a mild local form, Oriental Sore, exists in the Middle East primarily. Antibody levels appear to be elevated in both lepromatous leprosy and in diffuse cutaneous leishmaniasis, indicating that antibodies are unlikely to play a major role in protection.

T-lymphocyte clones from leprosy skin lesions

Introduction The immune response of patients with leprosy to antigens of Mycobacterium leprae correlaxad tes with a spectrum based upon cl inical and histopathologic categories ( I ) . Patients at the tuxad berculoid pole have strong cell-mediated immune responses whereas , patients at the lepromatous pole are selectively unresponsive to antigens of M. ieprae. The identification of epitopes recognized by lymphocytes from the res istant tuberculoid patients are important in designing an antileprosy vaccine . In addition , the mechanism of immune unresponsiveness of lepromatous patients i s of fundamental importance in contributing to our understanding of immune toler�nce in man (2) . The overwhelming majority of investigative studies into the immunology of leprosy has been performed on cells obtained from peripheral blood of patients . For example, Mehra et ai. described lepromin-induced suppressor T-lymphocytes in lepromatous patients which were thought to contribute to the unresponsiveness of these patients (3-5) . We have confirmxad ed these studies by measuring the effect of Dharmendra lepromin on the Concanavalin A (Con A) response of peripheral blood mononuclear cells (PBMC) . We were able to dexad monstrate suppressor cell activity in lepromatous and borderl ine lepromatous patients , but not in tuberculoid patients , normals or contacts (6) . Mehra further demonstrated that suppressor T-lymphocytes could be induced to suppress PBMC Con A responses by phenolic glycolipid-l (PG-I) (7) . In collaboration with B loom and Brennan (81 0 ) , we sought to define the epitope recognized by these suppressor cells . Suppression in lepromatous patients was observed with both synthetic terminal disaccharide and monosaccharide conj ugated to bovine serum albumin . Thus it appears that the terminal sugar unit of PGl i s the carbohydrate epitope recognized by T -suppressor cells from lexad promatous patients . In taking care of increas ing numbers of patients at Los Angeles County Hospital , we rexad cognize that leprosy is a disease of skin and nerves . The focal point of the immune response to M. ieprae is the granuloma, a col lection of lymphocytes and macrophages . Therefore , it is important to critically evaluate these cells in s i tes of disease activity .

Molecular Approaches to Developing a Vaccine for Leprosy

Leprosy, a chronic infectious disease afflicting 10 million to 15 million people, is caused by the obligate intracellular parasite Mycobacterium leprae. Although M. leprae was the first identified bacterial pathogen of man, it remains one of the few human pathogens that cannot yet be grown in culture. The inability to grow leprosy bacillus in culture has severely limited the understanding of the bacillus and the disease.