Short report: occurrence of Leishmania donovani DNA in donated blood from seroreactive Brazilian blood donors.

Human visceral leishmaniasis (kala-azar) transmitted by blood transfusion has been described in previous reports. Seroprevalence of antibodies to Leishmania donovani was shown to be related to prior blood transfusions in multiply transfused hemodialysis patients in Natal, Rio Grande do Norte, Brazil. In this study, a possible correlation between seroreactivity and the presence of L. donovani DNA was investigated in asymptomatic healthy blood donors. Sera were tested using the fucose mannose ligand (FML) ELISA, which was shown to have a sensitivity of 100%, a specificity of 96-100%, reliability, and diagnostic and prognostic potential for the detection of human and canine kala-azar, respectively. Leishmanial DNA was assessed by the polymerase chain reaction (PCR) and dot-blot hybridization techniques in blood and bone marrow samples. Among 21 FML-seroreactive asymptomatic blood donors, 5 (24%) were positive by the PCR and 9 (43%) were positive in a dot-blot assay of blood samples, showing a significant correlation (chi2 = 14.24, P < 0.01). No Leishmania DNA was detected in 20 FML non-reactive blood donors. Our results point to the need for control of transmission of kala-azar by blood transfusion in areas endemic for this disease.

Functional inactivation of primary T-cells stimulated in vitro in the presence of cyclosporine.

Cyclosporine (CsA) blocks in vitro polyclonal activation of primary murine T-cells in a complex manner. This cannot be completely reversed by exogenous IL2, and leads to a partial blockade in expression of the IL2 receptor (p55 chain) and, more intensely, in CD69. In proliferation assays, T-cells recovered from CsA-treated cultures and washed free from CsA were markedly refractory to restimulation in the presence of fresh accessory cells. In cell titration restimulation assays, CsA-treated, but not control T-cells, were also markedly unresponsive to accessory cell-independent stimuli provided by immobilized anti-CD3 antibody or rIL2, combined to phorbol ester. CsA-treated, but not control activated T-cells, undergo progressive cell death after drug removal and reculturing. In contrast, primary T-cells activated by a CsA-resistant pathway (rIL2 plus phorbol ester) and treated with CsA, did not develop unresponsiveness, compared to controls. When primary T-cells were stimulated with rIL2 plus phorbol ester in the presence of the calcium ionophore ionomycin, treatment with CsA resulted in marked unresponsiveness of the T-cells, compared to untreated controls. The data indicate that primary activation of T-cells in vitro in the presence of CsA induces an unresponsive state which lasts independent of the presence of CsA, and results in progressive cell death. We suggest that these effects could characterize one additional mechanism of CsA action in vivo.

Multiple disseminated pyogenic granuloma.

A 15-month-old baby girl with extensive skin burns developed within the burned areas multiple lesions with the clinical and histological characteristics of granuloma pyogenicum. These lesions seem to differ from those reported by others as pyogenic granuloma with multiple satellites.

Cyclophosphamide blocks both antigen-specific and polyclonal immunoglobulin responses in experimental visceral leishmaniasis.

Cyclophosphamide (Cy) has been shown to modulate antibody responses in a wide range of diseases both in humans and experimental animals. Our results in Syrian hamsters infected with Leishmania donovani have shown that Cy blocks specific and polyclonal antibody production both in vivo and in vitro. This effect was achieved by weekly 100 mg/kg doses and also by a 300 mg/kg single dose. Although Cy provokes a significant decrease in B-cell numbers in infected animals, this cannot explain the suppression of antibody production since a 50% decrease in B-cells of only-infected hamsters did not reproduce the same effect in in vitro assays. Also, this suppression was not reversed either by elimination of adherent cells or by the presence of indomethacin. These data suggest that Cy affects T-cell populations involved in the control of antibody production by B-cells.