Distribution of cathepsin D in human polymorphonuclear and mononuclear blood cells.

We have investigated the distribution of cathepsin D in mononuclear and polymorphonuclear cells using an anti-rabbit human cathepsin D antibody and indirect immunofluorescence. Lymphocytes showed the same fluorescence intensity as control cells incubated with normal serum. Fluorescence staining patterns of polymorphonuclear cells differed according to the fixative used. Monocytes and granulocytes fixed in ethanol, methanol, glutaraldehyde, and Bouin's fixative caused a homogeneous cytoplasmic staining with a distinct nuclear sparing. A perinuclear staining was seen in acetone-fixed cells in both monocytes and granulocytes. Another interesting difference was observed between monocytes and granulocytes when formalin was used as fixative. Monocytes appeared with a cytoplasmic staining, but in formalin-fixed granulocytes redistribution to the nuclear membrane was seen.