Depletion of immunoglobulin-secreting PCs from tonsil grafts. Tonsil grafts were recovered form xenochimeric mice at 4 weeks after surgery, and cells were assessed by multiparameter flow cytometry, with live cells sorted for analysis of immunoglobulin secretion by ELISPOT. (A) Expression of human IgD, CD19, CD20, CD27, CD38, CD52 in cells from the tonsil before surgery (tonsil), untreated (control), rituximab-treated (rituximab), and alemtuzumab-treated (Campath) mice. The percentage of positive cells in each quadrant and the percentage of PCs (CD38^bright) are shown. Lower panels show expression of human CD19, CD20, CD27, CD52 in PCs. (B) ELISPOT analysis of immunoglobulin secretion showing average spot frequency per 10 000 cells in grafts recovered from control (Con), rituximab-treated (Rit), and alemtuzumab-treated (Cam) mice. Bars represent SEM. (C) The percentage of PCs secreting immunoglobulin was calculated by expressing the number of spots as a percentage of the number of PCs in each well. (D) The mean spot size of cells secreting IgG (□) and IgM (▩) isolated from tonsil before surgery (TN), untreated (Con), rituximab-treated (Rit), or alemtuzumab-treated (Cam) mice was calculated. Bars represent SEM. (E) Sections of tonsil grafts from rituximab-treated mice were stained for expression of human CD138 (green), Ki-67 (blue), CD3 (red). Scale bar represents 50 μm. Results are representative of 4 experiments.