Identificação dos alelos HLA-DQB1*01 em pacientes hansenianos mitsuda negativos / Identification of HLA-DQB1*01 alleles in mitsuda negative leprosy patients

A proposta deste estudo foi identificar os alelos que codificam o HLA-DQ1 envolvidos na ausência de resposta imune celular em 60 pacientes hansenianos (50LL e 10BL) Mitsuda negativos. Os resultados obtidos mostraram a presença do alelo HLA-DQB1*0501 em 48.30% dos pacientes, seguido do HLA-DQB1*0602 em 31.66%, ambos subtipos do fenótipo HLA-DQB1*01. Apesar do predomínio destes alelos, não se pode afirmar que eles sejam os responsáveis pela ausência de resposta ao teste de Mitsuda. Sugerimos mais estudos neste segmento para a confirmação dos resultados.

The purpose of this study was to identify the gene encoding HLA-DQ1 involved in the absence of cellular immune response in 60 Mitsuda negative leprosy patients (50LL and 10BL). The results showed the presence of HLA-DQB1*0501 in 48.30% of patients, followed by HLA-DQB1*0602 in 31.66%, both subtypes of the phenotype HLA-DQB1*01. Despite the prevalence of these alleles, we can not say that they are responsible for the lack of response to the Mitsuda antigen. We suggest further studies to confirm the results.

Coupling of proteins to liposomes and their role in understanding delayed type of hypersensitivity in human and mice.

Liposome-coupled lepromin was found to elicit a 3-week skin reaction in leprosy patients similar to that elicited by whole Mycobacterium leprae. The present study suggests that the presentation of antigens in a specific orientation is necessary for evoking delayed type hypersensitivity response in humans.

Immunological unresponsiveness in leprosy and its relevance to immunoregulation in man.

The varied forms of leprosy form a clinical and immunological spectrum which offers extraordinary possibilities for insight into immunoregulatory mechanisms in man. At one pole, tuberculoid leprosy, patients develop high levels of cell-mediated immunity which ultimately results in killing of bacilli in the tissues, albeit often with damage to nerves. At the lepromatous pole, patients exhibit selective immunological unresponsiveness to antigens of Mycobacterium leprae. Even though all currently known protein species of Mycobacterium leprae and BCG are cross-reactive, lepromatous patients unreactive to Mycobacterium leprae antigens frequently respond strongly to tuberculin. In vitro experiments suggest the existence of lepromin-induced suppressor activity, mediated by both monocytes and Τ cells. The Τ suppressor cells have the T8 phenotype of which 50% express the activation markers, Ia and FcR. The one unique species of antigen of the leprosy bacillus is a phenolic glycolipid, and it appears that the Ts cells largely recognize the terminal trisaccharide of this unique antigen. Depletion of Ts cells restores in vitro reactivity of lymphocytes to lepromin in a portion of lepromatous patients, and addition of IL-2 containing supernatants partially restores responsiveness to Mycobacterium leprae antigens. Vaccination of lepromatous patients with a mixture of Mycobacterium leprae and live BCG restores cell-mediated immunity in the majority of lepromatous patients, and concomitantly reduces the in vitro suppressor activity and number of activated T8 cells. These experiments suggest the existence of stage-of-disease related suppressor cells in leprosy which appear to block the responsiveness of TH capable of responding to either specific or cross-reactive mycobacterial antigens. The mode of action of these Ts appears to be the inhibition of production of IL-2 and other lymphokines. Successful immunotherapeutic vaccination appears to overcome this block in the majority of patients.