PCR for identification of species causing American cutaneous leishmaniasis.

Parasites of the complexes Leishmania (Leishmania) mexicana, Leishmania (Viannia) braziliensis, and Leishmania (Leishmania) chagasi coexist within the same endemic areas of the American Continent. They produce similar clinical manifestations, yet not all respond well to treatment with anti-leishmania drugs. Thus, high specificity and sensitivity are needed to improve diagnosis and treatment. We developed a highly specific and sensitive polymerase chain reaction based diagnostic method that permits the identification of parasites belonging to the genus Leishmania and the differentiation between parasites belonging to the L. (L.) mexicana and L. (V.) braziliensis complexes and the identification of species of the L. (L.) mexicana complex, such as L. (L.) mexicana, Leishmania (L.) amazonensis, and Leishmania (L.) venezuelensis. This PCR permits the specific identification of Leishmania species in tissues of patients with different clinical forms of leishmaniasis. Its high sensitivity and specificity allow a precise diagnosis in lesions of patients that harbor few parasites, where the microscopic evaluation is unreliable. Additionally, this PCR could be a valuable tool for the identification of Leishmania species in mammalian reservoirs and sand fly vectors present in the American Continent.

Peripheral blood mononuclear cells proliferation and Th1/Th2 cytokine production in response to streptococcal M protein in psoriatic patients.

BACKGROUND: Psoriasis is a chronic skin disease that is probably a T cell-mediated autoimmune condition which is strongly associated with streptococcal throat infections. Although some groups have associated the involved response with different streptococcal antigens, M protein has been described as the major virulence factor of Streptococcus pyogenes. Thus, it is necessary to describe some features of the cellular responses to this streptococcal antigen. METHODS: Proliferation and Th1/Th2 cytokine production of peripheral blood mononuclear cells (PBMC) in response to total soluble extracts from type M5 S. pyogenes with (TSE37Sp) and without (M(-)TSESp) M protein were analyzed in 10 psoriatic patients and 10 healthy controls. RESULTS: PBMC from both patients and controls proliferated to both extracts. Responses to M(-)TSESp were significantly lower than those to TSE37Sp (P < 0.05). PBMC IL-2 and gammaIFN production after TSE37Sp stimulus was much higher than after M(-)TSESp antigenic stimulation in both groups (P < 0.05). Meanwhile, IL-4 production was quite low in both groups and in response to both extracts. We found a differential production of IL-10 between groups. PBMC from healthy controls responded to TSE37Sp with a much higher production of this cytokine as compared to the responses showed to M(-)TSESp while the cells from psoriatic patients responded without differences in the production of IL-10. CONCLUSION: Results obtained suggest an important Th1 response to M protein in psoriatic patients which could be associated with the cellular responses involved in psoriasis, while healthy subjects respond in a probably non-Th2 IL-10 producing regulatory T cells fashion.