Treatment with PCI-32765 affects spleen size and lymphocyte activation in B6.Sle1 mice. (A) Mice that received PCI-32765 are of similar weight compared to vehicle treated mice. All mice were weighed before sacrifice. (B-C) PCI-32765 reduces splenomegaly, but not kidney size, as measured by weight or cell number. Spleens and kidneys isolated from mice treated with PCI-32765 (n = 9) or vehicle (n = 8) for 56 days were weighed prior to the preparation of a single cell suspension of each tissue. Cells were then counted on a Cellometer Auto M10 automated cell counter (Nexcelom Bioscience, Lawrence, MA, USA). (D) Inhibition of Btk results in decreased lymphoid activation. Single cell suspensions were prepared from isolated spleens and stained for flow cytometry analysis of the indicated lymphocyte populations and activation status (CD69+). Each data point represents one mouse. Line represents mean ± standard error of the mean. *P < 0.05, **P < 0.005. Data were compared by two-tailed Student's t-test with Welch's correction.