Lepromin and Kveim antigen reactivity in man, and their relation to tuberculin reactivity

Evaluation of cell-mediated immune responses to two BCG vaccination regimes in young children in South Korea

Children in South Korea are vaccinated with either BCG Pasteur vaccine intradermally (ID), or with BCG Tokyo vaccine given by multipuncture device (MP). Data from a recent national survey indicated that in children under 6 years old, 31.1% had received the ID vaccine and 64.5% the MP vaccine. To compare the T cell responses induced by the two vaccines, children aged 3-7 were recruited and tested for tuberculin skin test reactivity and for in vitro IFN-γ responses to mycobacterial antigens. DTH responses were not significantly different in children vaccinated by either the ID or MP vaccines. PPD-induced IFN-γ was measured in supernatants of 6-day diluted whole blood cultures. IFN-γ production to PPD was not significantly different in the two vaccine groups, although there is a trend that the MP group gives a higher proportion of IFN-γ positivity than the ID group. In addition, when IFN-γ responses to the antigens ESAT-6 and CFP-10 were assessed in the 6-7 year old group, there was no significant difference between the two vaccine groups. Thus, there was no evidence that the increasing use of MP vaccination has reduced protection against M. tuberculosis in young children in South Korea, based on immunogenicity as assessed by DTH and IFN-γ responses to PPD, and also equivalent frequency of responses to ESAT-6 and CFP-10.

Etiology of sarcoidosis

Since sarcoidosis was first recognized as a distinct clinical entity, investigators have speculated that a transmissible agent may cause sarcoidosis. Recent attempts at directly isolating infectious organisms or indirectly detecting microbial DNA or RNA from sarcoid tissue have led to inconclusive results. Studies on the immunopathogenic origins of sarcoidosis have provided evidence of persistent antigenic stimulation at sites of inflammation that are associated with dysregulated cytokine production. To date, however, the challenge of defining the cause of sarcoidosis remains unmet.

Fatores envolvidos na reatividade do PPD em pacientes com doença de Hansen

Foram testados intradermicamente com PPD (RT23 e FAP5U) 236 pacientes hansenianos (138 multibacilares e 98 paucibacilares) e 291 contatos sadios. Observa-se um percentual menor de reatores ao PPD em pacientes multibacilares (42%), quando comparados a paucibacilares (62,2%) e contatos sadios (63,2%). Entre os pacientes multibacilares, o índice bacteriológico (IB) mostrou ser fator de interferência na resposta ao PPD, sendo significativamente maior o percentual de respondedores em pacientes com IB negativo, quando comparados aos com IB igual ou acima de 3. Foi observado um elevado índice de positividade à tuberculina em contatos sadios (61,0%) e pacientes paucibacilares (65,3%) com teste de Mitsuda positivo.

Early cellular responses to intradermal injection of Kveim suspension in normal subjects and those with sarcoidosis

In a detailed controlled study of the cellular response to Kveim suspension in vivo we used immunohistological and histochemical methods to examine cryostat sections of immature Kveim biopsy specimens in subjects with sarcoidosis and normal controls. Changes seen at 48 hours, at which time papular reactions have sometimes been reported, are described. Eight cases of sarcoidosis previously confirmed by a positive Kveim test were studied, in five of whom the test remained positive; plus two subjects with sarcoidosis studied prospectively; and four healthy controls. There were two main features of the 48 hour response: collagen disruption with associated histiocytes, which showed increased acid phosphatase activity; and perivascular infiltrates of lymphocytes and small groups of dendritic cells. The T4:T8 ratios in the infiltrates were similar to those found in the peripheral blood of the subjects, and few lymphocytes showed evidence of activation. T lymphocytes were also seen free in the dermis and migrating to the epidermis. Small juxtacapillary clumps of dendritic cells, identified by NA1/34 (= OKT6; Langerhans' cells) and RFD1 (interdigitating cell) monoclonal antibodies, were found. The Langerhans' cells in the epidermis were, however, normal in number and distribution. These features, which were found in all groups, are not consistent with pre-existing hypersensitivity to Kveim suspension in sarcoidosis. Subsequent differences between sarcoid and normal subjects in the development of granulomas in the Kveim response may therefore relate to the different handling of the foreign material by the cells affected, rather than to differences in the early non-specific recruitment of the cells to the test site.

In-vitro inhibition of leucocyte migration in Crohn's disease by a sarcoid spleen suspension

A Kveim suspension has been shown to inhibit the migration of leucocytes in vitro from 12 out of 18 patients with Crohn's disease but to have no comparable effect on leucocytes from patients with ulcerative colitis or from a group of patients with other diseases. These findings provide further evidence of cross-reactivity or of a possible aetiological link between Crohn's disease and sarcoidosis and suggest a further immunological distinction between Crohn's disease and ulcerative colitis.

Cell-mediated immunological processes in leprosy

A large number of organisms such as viruses, protozoa, helminths, fungi and bacteria, especially mycobacteria, need cell-mediated immunological processes for their elimination. As well as being involved in protection, cell-mediated immunological processes are also involved in a number of allergic reactions to products derived from mycobacteria. Cell-mediated immunological processes can be demonstrated by a number of in vitro reactions. Leprosy can present with a wide range of different clinical patterns. The clinical spectrum of leprosy can be shown to depend on the degree of the cell-mediated immune response of the host against Mycobacterium leprae. Thus in tuberculoid leprosy there is a high degree of cell-mediated immune response whereas in lepromatous leprosy such a response is virtually absent. There appears to be a constitutional predisposition to lepromatous leprosy. In addition to a specific loss of cell-mediated immune response against Myco. leprae, there is also a non-specific drop in the ability of patients with lepromatous leprosy to show other aspects of cell-mediated immune response, e.g., contact sensitivity and skin homograft rejection. There is also a relative impairment of the ability of lymphocytes to react in vitro. Lymph nodes from patients with lepromatous leprosy show a deficiency in those areas associated with the development of cell-mediated immune responses.The article includes a discussion on the possible causes of deficiencies in cell-mediated immune responses in lepromatous leprosy.