Sp17 is expressed on the surface of normal circulating lymphocytes.

(A) PBMCs from healthy donors were dual stained with antiserum to Sp17 and a monoclonal antibody specific for T lymphocytes (anti-CD3) or B lymphocytes (anti-CD19) and then analyzed by flow cytometry. Dot plots (upper panels) show the subpopulation of CD3⁺ and CD19⁺ cells, and histograms (lower panels) show the staining profile for Sp17 of those 2 subpopulations. (B) Sp17 is also present on polymorphonuclear leukocytes (PMNs) and monocytes. To distinguish PMN and monocyte populations, the light scatter pattern (forward versus side light scatter) was used. Data in panels A and B are representative of 2 to 4 independent experiments. (C) Amplification of Sp17 mRNA by RT-PCR confirms that normal PBMCs are producing the cell surface Sp17 that is detected by flow cytometry.