Identification of resting human T and B lymphocytes by acid alpha-naphthyl acetate esterase staining combined with rosette formation with Staphylococcus aureus strain Cowan 1.

We describe a method enabling the identification of both lymphocyte class and morphology from a single microscopic slide. As a marker for B cells we used surface immunoglobulin. The surface-Ig-carrying cells were rosetted after poly-valent anti-Ig treatment with Staphylococcus aureus strain Cowan 1 (StaCw) and the cells were cytocentrifuged onto a microscope slide. The lymphocytes forming rosettes with StaCw were identical with cells expressing surface Ig studied by fluorescein-isothiocyanate-conjugated anti-Ig. As a marker for T cells we used the acid alpha-naphthyl acetate esterase (ANAE) histochemical marker. The cell smears were first stained for ANAE and subsequently counterstained to distinguish also cell morphology. The ANAE-marker-carrying cells were all included in the population of lymphocytes forming rosettes with sheep erythrocytes. Thus both T and B lymphocytes could be simultaneously identified from a single microscopic slide, and we therefore recommend the method for routine clinical work.