Association of HLA specificity LB-E12 (MB1, DC1, MT1) with lepromatous leprosy in a Venezuelan population.

To investigate whether an association could be found between HLA and lepromatous leprosy a population study was performed in Tachira, Venezuela. This was done in the same endemic area in which recently both non-random parental HLA-haplotype and preferential segregation of the HLA specificity LB-E12 (MB1, DC1, MT1) was demonstrated in lepromatous leprosy patients from multicase families. In this study 32 lepromatous patients and 32 healthy controls were typed for HLA-A, -B, -C, -DR and the specificities MB and MT. The frequency of LB-E12 (MB1, DC1, MT1) showed a significant increase in lepromatous leprosy patients (p = 0.04). This is the first report concerning HLA and leprosy which confirms in the same endemic area an association observed in families on the population level.

HLA-DR-associated genetic control of the type of leprosy in a population from surinam.

The relationship between HLA phenotype and leprosy classification was studied in 73 unrelated patients and 92 healthy controls from a mixed Negroid-Caucasoid population originating from Surinam, South America. Heterogeneity in the distribution of HLA-DR (but not A, B, and C) was detected between tuberculoid (TT* + BT*) leprosy and lepromatous (BL* + LL*) leprosy patients (p = 0.024). This heterogeneity appeared to be caused almost exclusively by DR3. Most significantly, the frequency of DR3 was increased among polar tuberculoid (TT) leprosy patients as compared to the rest of the patients (p = 0.0003). Compared with healthy controls the frequency of DR3 was increased among TT patients (p = 0.006), unchanged in BT patients, and decreased among lepromatous (BL + LL) patients (p = 0.027). These data indicate that in this population an DR3-associated factor controls the type of the disease that develops after infection with Mycobacterium leprae.

Natural supressor cells in human leprosy: the role of HDLA-D-identical peipheral lymphocytes and macrophages in the in vitro modulation of lymphoproliferative responses

Six families with HLA-D-identical siblings suffering from leprosy were studied. Lymphocytes and macrophages isolated from the peripheral blood were co-cultured with allogeneic, HLA-D-identical cells and stimulated with M. Leprae antigens and concanavalin A. tuberculoid patients had circulating lymphocytes which showed marked functional suppression of lymphoproliferative responses to antigen and mitogen. In contrast, lepromatous patients showed weak lymphocyte suppressor activity. Macrophages derived from responder individuals augmented, while those derived from lepromatous patients inhibited, M. leprae-induced proliferation of lymphocytes.

Genetic control of survival in epidemics.

Descendants of Dutch colonists, who emigrated to Surinam in the last century and survived epidemics of typhoid and yellow fever with a total mortality of about 60%, were tested for twenty-six polymorphisms. The gene frequencies were compared with those of a large Dutch control sample. An analysis of drift indicated that the variations in gene frequencies observed for C3, Gm, HLA-B, and GLO were unlikely to be due to drift. Therefore these data might indicate selection through genetic control of survival in these epidemics.