Involvement and interactions of different immune cells and their cytokines in human visceral leishmaniasis

Visceral leishmaniasis (VL) or kala-azar, a disseminated infection of the lymphoreticular system of the body, is marked by severe defect in immune system of the host. Successful cure of VL depends on the immune status of the host in combination with the effects of the antileishmanial drugs. The rationale approach towards eradication of this disease would be to potentiate the immune functioning of the host in addition to parasite killing. This review deals with different aspects of adaptive and innate immune responses and explores their role in protection or pathogenesis of VL. IL-10 has emerged as the principal cytokine responsible for disease pathogenesis, although evidences regarding its source during active VL remain inconclusive. On the other hand, IFNγ, under the influence of IL-12, is mostly correlated with healing of the disease. Chemokines are important in mounting cell-mediated immune response as they can prevent parasite invasion in association with cytokines. Different types of T cells like CD4, CD8 and NK T cells also contribute to the immunology of this disease. In spite of conflicting reports, the role of regulatory T cells in VL pathogenesis is important. Recently discovered Th17 subset and its different members have been reported to perform diverse functions in the course of VL and leishmaniasis as a whole. Innate immune responses, depending on the cell types, are essential in early parasite detection and subsequent development of an efficient NK cell response. Immunotherapy targeting IL-10 could be looked upon as an interesting option for the treatment of VL.

Immune responses in kala-azar.

Human infection with Leishmania results in diverse clinical and immunopathological situations. The capacity of the parasites to cause this wide range of disease manifestations depends upon their ability to evade the immune defense mechanisms by performing a well-tuned orchestra of hostparasite interactions inside the macrophages. While updated knowledge focus on the key role of cell-mediated immunity (CMI) in protection, the survival strategies of the parasites leads to the suppression of CMI which can further be aggravated by the co-infections with HIV, tuberculosis etc. The present review describes the immune mechanisms in human leishmaniasis with a special attention to visceral leishmaniasis or kala-azar, one of the most important epidemiological health problems in Indian subcontinent. Modulations of the both humoral and cell-mediated immune responses during asymptomatic infections, active disease and after successful chemotherapy are discussed. The components responsible for the regulation of the critical balance of Th1/Th2 type of responses are re-evaluated. Co-infection of HIV and visceral leishmaniasis and their interdependence has been addressed. Although the specific role of an elevated humoral response in kala-azar is yet to be established, attempts for its application in diagnosis, precisely for the development of field diagnostic techniques, are presented. Also discussed are attempts to utilize the immunogenic potentials of different leishmanial antigens in the development of anti-leishmanial vaccines.

A study on cryopreservation of cultured rabbit periodontal ligament cells.

Cultured rabbit periodontal ligament cells were subjected to short term cryopreservation in liquid nitrogen, for a period of 84 hours and 168 hours, to study the effect of cryopreservation on coll viability and culturing ability. The vital cell count performed by Trypan Blue exclusion was 14.93 x 10(0) cells/ml in vial A and 9.11 x 10(6) cell/ml in vial B, before cryopreservation. The loss of viability was minimal--vital cell count being 14.64 x 10(6) cells/ml in vial A and 8.87 x 10(6) cells/ml in vial B after 84 hrs of cryopreservation and 14.6 x 10(6) cells/ml in vial A and 8.82 x 10(6) cells/ml in vial B after 168 hours of cryopreservation. The cryopreserved cells after thawing could grow again in cultured.