Figure 2A Total cellularity of thymus spleen and of mesenteric and peripheral LNs of WT and Arhgap45-/- mice (see key in upper right corner). Data information: In (A) the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. Mean and SD are also shown. B Upon thymus colonization, ETP develop into CD4-CD8-double negative (DN) cells that mature into CD4+CD8+ double positive (DP) cells, some of which proceed further into CD4+ and CD8+ single positive (SP) cells that egress from the thymus. Based on the expression of CD25 and CD44, DN cells can be further organized according to the following developmental series: DN1 (CD44+CD25−) → DN2 (CD44+CD25+) → DN3 (CD44−CD251+) → DN4 (CD44−CD25−). After excluding cells positive for CD11b, CD11c, CD45R, or CD161c, WT and Arhgap45-/- thymocytes were analyzed by flow cytometry for expression of CD4, CD8, CD25, and CD44 and the numbers of cells present in each of the specified T cell developmental stages determined. Data information: In the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. Mean and SD are also shown. C Numbers of T and B cells found in the blood of WT and Arhgap45-/- mice. Data information: In the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. Mean and SEM are also shown. D Numbers of T and B cells found in pooled mesenteric and peripheral LNs of WT and Arhgap45-/- mice. Data information: In the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. SEM are also shown. E Numbers of T and B cells found in the Peyer's patches of WT and Arhgap45-/- mice. Data information: the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. Mean and are also shown. F In the spleen, IgMhiIgDlo transitional 1 (T1-Bc) B cells constitute recent immigrant from the BM that develop into IgMhiIgDhi transitional (T2-Bc) B cells, which differentiate into mature IgMloIgDhi, or follicular recirculating B cells Fol-Bc (Carsetti, 2004)). WT and Arhgap45-/- splenocytes were analyzed by flow cytometry for expression of CD19, CD45R, IgM and IgD and the numbers of cells present in each of the specified B cell developmental stages determined. Data information: In the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. Mean and SEM are also shown. G Numbers of total CD4+ and CD8+ T cells, and of naïve and effectors CD4+ and CD8+ T cells found in peripheral LNs of WT and Arhgap45-/- mice. Also shown are CD62L levels on naïve CD4+ and CD8+ T cells from WT and Arhgap45-/-. Data information: In the results for each mouse are shown as a dot and correspond to three to four experiments involving a total of 12-25 mice. * P ≤ 0.033, ** P ≤ 0.002, *** P ≤ 0.001, **** P ≤ 0.0001; unpaired Student's t test. Mean and SD are also shown. H CD4+ and CD8+ T cells from peripheral LNs analyzed for expression of CD44 and CD62L. Numbers in quadrants indicate percent naïve (CD44loCD62Lhi) and central memory CD8+ T cells (CD44hiCD62Lhi).