In vitro maintenance of Leishmania amastigotes directly from lesions: advantages and limitations.

Leishmania amazonensis (MHOM/BR/77/LTB0016) amastigotes were obtained from mouse cutaneous lesions and maintained in vitro for 48 hr at pH 4.6, 33 C. These organisms were reproducing, capable of transformation to promastigotes, and did not display the promastigote-specific antigen, GP46. In contrast, 97% of the organisms maintained for 24 hr at 31 C, pH 7.3, were positive for GP46. Thus, short-term cultivation of this L. amazonensis strain under appropriate conditions can provide a high yield of amastigotes for various in vivo and in vitro studies. However, the possible interference of host immunoglobin on the surface of these amastigotes needs to be considered because fluorescent-labeled anti-mouse immunoglobulin was detected on 16% of lesion-derived amastigotes even after 114 hr of cultivation.