MS4a4B protein is expressed in thymocytes. (A) Double-negative thymocytes were analyzed by flow cytometry using 4-color staining. The samples were gated first on the CD4/CD8 double-negative population and subsequently on the 4 subsets of CD44 and CD25 expression, and then analyzed for MS4a4B as shown. Fluorescence intensity of MS4a4B (solid heavy line) or rabbit IgG control (light line) in each selected subset. (B) Total thymocytes were analyzed by flow cytometry as described in “Materials and methods” using 3-color staining. CD4 and CD8 were used for gating thymocyte subpopulations, and anti-MS4a4B (bold line) or Ig as control (light line) was analyzed subsequently as shown. Results shown are representative of 2 separate experiments.