The hamster cheek pouch: an immunologically privileged site suitable to the study of granulomatous infections.

The hamster cheek pouch is an invagination of oral mucosa, characterized histologically as skin-like. In this paper we describe anatomical, histological and embriological features of the pouch and comment on the pouch as an immunologically privileged site since it lacks lymphatic drainage and has few Langerhans cells. We present the review from literature and our observations after inoculation in the pouch of mycobacteriae (BCG, Mycobacterium tuberculosis and Mycobacterium leprae) and a fungus (Paracoccidioides brasiliensis). Lesions in the pouch were granulomatous but smaller and long lasting; even granulomatous, the reaction was inefficient to control the proliferation of agents compared with inoculation in other sites, except for BCG. Appearance of immunity was also delayed or absent and, when it was detected, a sharp decrease in number of agents in pouch lesions was observed. These observations make the pouch an interesting site for the study of the role of immune system in infectious diseases and in granuloma formation.

[Assessment of the Mitsuda reaction in lepromatous patients inactive before and after immunotherapy]. / Avaliação da reação de Mitsuda em pacientes virchovianos inativos antes eapós imunoterapia.

In this study the immunopotentiator levamisole as well as a mixture of BCG/Mycobacterium leprae were investigated in inactive lepromatous leprosy patients by using the Mitsuda reaction as a parameter. Twenty lepromatous patients ten years ago classified as histologically negative for Mitsuda's test were divided into three groups: five patients that were only retested with Mitsuda antigen; eight patients that received oral levamisol and seven patients that received a mixture of alive BCG plus autoclaved M. leprae. The results indicated that: 1) the levamisole did not alter the reactivity to lepromin in any of the patients studied; 2) neither the changes in the reactivity to lepromin by using the mixture (3 cases) nor those that occurred spontaneously (3 cases) were clear. They properly reflected the natural variation of patients with some degree of resistance to Mycobacterium leprae.

[Cellular immunity in leprosy patients]. / Estudo da imunidade celular em pacientes branqueados.

Forty eight clinically arrested lepromatous patients were submitted to several tests to evaluate cellular immunological competence (PPD, Trichophytin, DNCB, determination of the percentage of T lymphocytes in the peripheral blood, and early and late reactions to the lepromin). The results of the Trychophytin test and of the lymphocyte percentage test did not differ from those of the control group, whereas the results to the PPD test were more often positive for the arrested Virchovian cases. All the patients presented positivity to the DNCB test, and none of them showed positivity to the Fernandez reaction. As for the late reaction to the lepromin, all the patients were negative, although in histopathological testing four degrees of reactivity was observed ranging from focal, non specific inflammatory reaction to granulomatous histiocytic with an epithelioid outline. By means of these results the authors were able to confirm that: 1. There is no cross reactivity between the PPD and lepromin tests. 2. Sulfone therapy does not interfere in immunocellular results for the tests employed. 3. Lepromatous patients respond like the general population to the unspecific sensitivity tests utilized. 4. The finding of histiocytic reaction with epithelioid outline in some biopsies of Mitsuda reaction in lepromatous patients, suggests the presence of a sub-population within this group, probably Borderline patients that suffered during the infection's evolution downgrading of theirs clinic and histological characteristics.