Plasmacytoid dendritic cells in cutaneous lesions of patients with chromoblastomycosis, lacaziosis, and paracoccidioidomycosis: a comparative analysis.

Plasmacytoid dendritic cells (pDCs) are characterized by expression of CD123 and BDCA-2 (Blood Dendritic Cell Antigen 2) (CD303) molecules, which are important in innate and adaptive immunity. Chromoblastomycosis (CBM), lacaziosis or Jorge Lobo's disease (JLD), and paracoccidioidomycosis (PCM), are noteworthy in Latin America due to the large number of reported cases. The severity of lesions is mainly determined by the host's immune status and in situ responses. The dendritic cells studied in these fungal diseases are of myeloid origin, such as Langerhans cells and dermal dendrocytes; to our knowledge, there are no data for pDCs. Forty-three biopsies from patients with CBM, 42 from those with JLD and 46 diagnosed with PCM, were evaluated by immunohistochemistry. Plasmacytoid cells immunostained with anti-CD123 and anti-CD303 were detected in 16 cases of CBM; in those stained with anti-CD123, 24 specimens were obtained from PCM. We did not detect the presence of pDCs in any specimen using either antibody in JLD. We believe that, albeit a secondary immune response in PCM and CBM, pDCs could act as a secondary source of important cytokines. The BDCA-2 (CD303) is a c-type lectin receptor involved in cell adhesion, capture, and processing of antigens. Through the expression of the c-lectin receptor, there could be an interaction with fungi, similar to other receptors of this type, namely, CD207 in PCM and CD205 and CD209 in other fungal infections. In JLD, the absence of expression of CD123 and CD303 seems to indicate that pDCs are not involved in the immune response.

LILRA2 activation inhibits dendritic cell differentiation and antigen presentation to T cells.

The differentiation of monocytes into dendritic cells (DC) is a key mechanism by which the innate immune system instructs the adaptive T cell response. In this study, we investigated whether leukocyte Ig-like receptor A2 (LILRA2) regulates DC differentiation by using leprosy as a model. LILRA2 protein expression was increased in the lesions of the progressive, lepromatous form vs the self-limited, tuberculoid form of leprosy. Double immunolabeling revealed LILRA2 expression on CD14+, CD68+ monocytes/macrophages. Activation of LILRA2 on peripheral blood monocytes impaired GM-CSF induced differentiation into immature DC, as evidenced by reduced expression of DC markers (MHC class II, CD1b, CD40, and CD206), but not macrophage markers (CD209 and CD14). Furthermore, LILRA2 activation abrogated Ag presentation to both CD1b- and MHC class II-restricted, Mycobacterium leprae-reactive T cells derived from leprosy patients, while cytokine profiles of LILRA2-activated monocytes demonstrated an increase in TNF-alpha, IL-6, IL-8, IL-12, and IL-10, but little effect on TGF-beta. Therefore, LILRA2 activation, by altering GM-CSF-induced monocyte differentiation into immature DC, provides a mechanism for down-regulating the ability of the innate immune system to activate the adaptive T cell response while promoting an inflammatory response.

Quantitation of the soluble E-receptor of human T lymphocytes by rocket electrophoresis in the serum of patients with lepromatous and tuberculoid leprosy.

Human T lymphocytes carry a membrane receptor for sheep erythrocytes (E) which is responsible for the well-known phenomenon of E-rosette formation. This receptor has been related to CD2 molecules; it is present in a soluble form (Rs) in normal serum and may play an immunoregulatory role. In this study we quantitated soluble E-receptor in serum samples of 43 normal controls, 32 patients with tuberculoid leprosy and 53 with lepromatous leprosy, using rocket electrophoresis and an anti E receptor serum (anti-Rs) obtained from an adult sheep immunized with autologous E treated with Rs. In the 3 groups studied, the rocket means were respectively 5.0, 7.5 and 10.9 mm (p less than 0.001). We found abnormally high levels of Rs in the serum of various diseases associated with a depression of cell-mediated immunity. The increase of Rs levels in the serum may be one of the mechanisms responsible for the depression of cellular immunity in leprosy.

Quantitation of the soluble E-receptor of human T lymphocytes by rocket electrophoresis in the serum of patients with lepromatous and tuberculoid leprosy

Los linfocitos T humanos poseen, a nivel de membrana, receptores para eritrocitos de carnero (E) que les permite la unión espontánea con estas células, llevando al fenómeno de formación de rosetas. Este receptor fue relacionado con la molécula CD2. Se produjeron varios anticuerpos monoclonales contra la estructura CD2; la mayoría de ellos inhibe alguna de las funciones de los linfocitos T (blasogénesis, formación de rosetas y reacción en cultivo mixto de linfocitos). Es posible obtener este receptor de membrana en forma soluble (Rs), en el sobrenadante de células T incubadas por una hora a 4-C y en el suero de individuos normales. En nuestro laboratorio fueron estandarizados varios métodos para detección y ccuantificacióne de Rs, a partir de un antisuero (anti-Rs) obtenido al inmunizar un carnero con eritrocitos autólogos tratados con Rs (ERs). Este antisuero inhibe la formación de rosetas, es citotóxico para células T, aglutina complejos ERs e identifica linfocitos T por inmunofluorescencia. El método más práctico para cuantificacióne de Rs es el suero de pacientes con patologías asociadas a depresión de la respuesta inmune mediada por células (anemia, lepra, neoplasias, leucemias, linfomas y aplasia medular). Numerosos trabajos han demostrado que los pacientes portadores de lepra presentan alteraciones inmunológicas. Se sabe que los pacientes con lepra lepromatosa presentan deficiencia primaria específica de células T contra antígenos del M. leprae y deficiencia secundaria, inespecífica, de la respuesta inmune celular. En este trabajo, cuantificamos Rs por inmunoelectrdifusión en el suero de 43 individuos normales, 32 pacientes con lepra tuberculoide y 53 con lepra lepromatosa. El promedio de los picos obtenidos fue de 5,0, 7,5 y 10,9 mm., respectivamente. Este aumento fue estadísticamente significativo (Kruskal-Wallis p<0,001), entre los 2 grupos de pacientes y comparados con el grupo control. El aumento de Rs en el suero de los pacientes con lepra puede ser uno de los mecanismos responsables de la depresión de la respuesta inmune celular encontrada en esta enfermedad

Quantitation of the soluble E-receptor of human T lymphocytes by rocket electrophoresis in the serum of patients with lepromatous and tuberculoid leprosy

Los linfocitos T humanos poseen, a nivel de membrana, receptores para eritrocitos de carnero (E) que les permite la unión espontánea con estas células, llevando al fenómeno de formación de rosetas. Este receptor fue relacionado con la molécula CD2. Se produjeron varios anticuerpos monoclonales contra la estructura CD2; la mayoría de ellos inhibe alguna de las funciones de los linfocitos T (blasogénesis, formación de rosetas y reacción en cultivo mixto de linfocitos). Es posible obtener este receptor de membrana en forma soluble (Rs), en el sobrenadante de células T incubadas por una hora a 4-C y en el suero de individuos normales. En nuestro laboratorio fueron estandarizados varios métodos para detección y ccuantificacióne de Rs, a partir de un antisuero (anti-Rs) obtenido al inmunizar un carnero con eritrocitos autólogos tratados con Rs (ERs). Este antisuero inhibe la formación de rosetas, es citotóxico para células T, aglutina complejos ERs e identifica linfocitos T por inmunofluorescencia. El método más práctico para cuantificacióne de Rs es el suero de pacientes con patologías asociadas a depresión de la respuesta inmune mediada por células (anemia, lepra, neoplasias, leucemias, linfomas y aplasia medular). Numerosos trabajos han demostrado que los pacientes portadores de lepra presentan alteraciones inmunológicas. Se sabe que los pacientes con lepra lepromatosa presentan deficiencia primaria específica de células T contra antígenos del M. leprae y deficiencia secundaria, inespecífica, de la respuesta inmune celular. En este trabajo, cuantificamos Rs por inmunoelectrdifusión en el suero de 43 individuos normales, 32 pacientes con lepra tuberculoide y 53 con lepra lepromatosa. El promedio de los picos obtenidos fue de 5,0, 7,5 y 10,9 mm., respectivamente. Este aumento fue estadísticamente significativo (Kruskal-Wallis p<0,001), entre los 2 grupos de pacientes y comparados con el grupo control. El aumento de Rs en el suero de los pacientes con lepra puede ser uno de los mecanismos responsables de la depresión de la respuesta inmune celular encontrada en esta enfermedad (AU)

Defective intralesional interferon-gamma activity in patients with lepromatous leprosy.

Cryostat sections of full-thickness skin biopsies from 21 patients along the whole spectrum of leprosy were subjected to immunohistological examination with special regard to defective lymphokine production. There was an inverse relationship between intra-lesional IL-1 reactivity and IL-2R expression, in that the latter was markedly observed in tuberculoid lesions. Whenever epithelioid cell containing granulomas were present in paucibacillary forms, significant reactivity within the central phagocytic cells with the monoclonal antibody directed against interferon-gamma was detectable. The keratinocytes covering tuberculoid lesions abundantly expressed class II alloantigens (HLA-DR antigens), indicating high intra-lesional interferon-gamma activity. In contrast, multibacillary forms revealed significant anti-IL-1 reactivity within the cellular infiltrate. IL-2R bearing cells were virtually absent as was anti-HLA-DR reactivity of the keratinocytes, underlining a defective intra-lesional interferon-gamma activity.

Quantitative analysis of contrasuppressor T lymphocytes in leprosy; induction of Ia antigens with gamma interferon.

Lepromatous leprosy is characterized by immune anergy and abnormal suppressor T-cell function. Contrasuppressor cells are a subset of CD8+, vicia villosa-adherent T lymphocytes. T-contrasuppressor (Tcs) cells act on T-helper cells to cause them to become unresponsive to the action of T-suppressor cells. In 8 lepromatous (LL) and 7 tuberculoid (TT) patients, and 6 healthy contacts we studied the percent of the following lymphocyte subsets: CD3+, CD4+, CD8+, Ia+, vicia villosa+ (VV+), CD8, VV+, VV, Ia+, and Ia, Tac+. This was done in baseline status as well as post-stimulation with recombinant gamma interferon (rIFN-gamma). We found that peripheral blood mononuclear cells from LL and TT patients and controls exhibit a similar number of putative contrasuppressor lymphocytes (CD8, VV+ cells). However, in the contrasuppressor subset from LL patients we found a low percent of Ia+ (p less than 0.05 compared to controls or TT). In the three groups studied, the rIFN-gamma enhanced the percent of Ia+ lymphocytes in the CD8, VV+ cell subpopulation. However, the CD8, VV+ lymphocytes from LL patients, despite the effect of rIFN-gamma, continue to have a low percent of Ia+ cells (p less than 0.05 compared to controls or TT). These findings suggest that LL patients might have abnormalities in the contrasuppressor immune circuit. Future functional studies on the role of Tcs cells in the anergy seen in LL will be required in order to define the apparent dysfunction occurring in this disease.

In situ characterization of the cellular immune response in American cutaneous leishmaniasis.

American cutaneous leishmaniasis is a spectrum of granulomatous disease caused by related species of an intracellular parasite. The host response in localized cutaneous leishmaniasis (LCL) is effective in that few organisms can be found in tissue lesions. In contrast, diffuse cutaneous leishmaniasis (DCL) patients mount a poor response with numerous parasites present in multiple skin lesions. Immunopathological correlates were sought in LCL and DCL with immunoperoxidase techniques using monoclonal antibodies directed against T lymphocyte subpopulations and interleukin-2 in tissue lesions. Both LCL and DCL granulomas showed a mixture of T lymphocyte subpopulations with the ratio of helper:suppressor phenotypes less than one. This ratio and localization of cells is more similar to the ineffective lepromatous leprosy granuloma than the effective tuberculoid leprosy granuloma. In contrast, interleukin-2 was identified in equivalent numbers of cells in LCL and tuberculoid leprosy, an order of magnitude greater than DCL and lepromatous leprosy lesions. Cells expressing Tac, the receptor for interleukin-2, were present in approximately equal numbers in all disorders. The immunological effectiveness of granulomas appear to related less to the numbers and location of T cell phenotypes than to the functional aspects of these cells, particularly the ability to generate lymphokines.

The in situ characteristics of mononuclear cell infiltrates in dermal lesions of leprosy.

The in situ nature of mononuclear cell infiltrates in the dermal lesions of 38 untreated leprosy patients was studied by means of conventional surface marker techniques using erythrocytes coated with AET, anti-erythrocyte IgG antibody, hemolysin and complement for the identification of T cells, and cells bearing Fc and C3 receptors, respectively. In general, T cells were the predominant lymphocytes in the leprosy lesions. They were mostly seen to be associated with epithelioid cell granulomas and showed maximal density in tuberculoid leprosy. A graded reduction of T cells was observed in borderline leprosy with a severe reduction/absence in polar lepromatous leprosy. The cells of the mononuclear phagocyte series in the various granulomas of the leprosy spectrum showed the presence of Fc and C3 receptors. Cells bearing a higher density of these receptors had a peripheral localization; whereas cells showing diffuse staining for nonspecific esterase were located more in the central regions of the granulomas. The differences in the individual cells of the phagocytic series appeared to be related to cell maturity; whereas the quantity of T cell infiltration in the lesions showed a correlation with the leprosy spectrum.