Flow cytometric analysis of CD300a expression on human peripheral blood and tonsil B cells. (A) Freshly isolated PBMCs were labeled with anti-CD19 and anti-CD300a mAb. The lymphocyte gate was determined according to the forward and side scatter parameters. The expression of CD300a was assessed on B cells (CD19⁺). Empty histogram represents binding of anti-CD300a mAb; and gray histogram, the binding of isotype control Ig. (B) Freshly isolated PBMCs were labeled with anti-CD19, anti-IgD, anti-CD27, and anti-CD300a mAb. The expression of CD300a for a representative donor was measured for the 4 subsets within the CD19⁺ gate (B cells) defined by the expression of IgD and CD27. The number in the histograms indicates the percentage of CD300a⁺ cells. (C) Single-cell suspensions from tonsils were labeled with anti-CD19, anti-IgD, anti-CD38, and anti-CD300a mAb. The expression of CD300a for a representative donor was measured in the 5 subsets of the CD19⁺ gate (B cells) defined by the expression of IgD and CD38. The number in the histograms indicates the percentage of CD300a⁺ cells.