Fig. 1.
Detection by monoclonal antibodies (mAb) of Poly α 2,8 N-acetyl neuraminic acid (PSA) and PSA containing de-N-acetyl neuraminic acid (NeuPSA) in Leishmania major. Promastigote cells were labeled with each mAb indicated and examined by flow cytometry. Upper panel, binding without Triton X-100 exposure to detect only surface-associated antigens; lower panel, mAb binding after a 10 min Triton X-100 exposure to detect both cytoplasmic and surface-associated antigens. Black fill, binding of indicated mAb; white fill, irrelevant isotype matched control mAbs. Results indicate that nearly all leishmanial promastigotes possess PSA/NeuPSA internally, but only a small fraction of the population expresses these antigens on their surface when grown at 24--26 °C. In contrast, nearly all cells express cell surface gp63 under the same culture conditions.
