Effect of CTLA4-Ig injection in scurfy mice. (A) Lifespan of CTLA4-Ig–injected (dotted line, n = 5) and phosphate-buffered saline–injected (solid line, n = 3) scurfy mice. Intraperitoneal CTLA4-Ig injection took place every 4 days from day 7 until day 19 after birth (shown above the panel) (P < .001). (B) Total cell number of inguinal lymph nodes from phosphate-buffered saline– and CTLA4-Ig–injected scurfy (sf) and wild-type (wt) mice. (C,D) Surface antigen analysis of T cells from CTLA4-Ig–injected scurfy mice. Numbers in each quadrant indicate the percentage of cells in each region against the total. (C) CD4 and CD8 and (D) CD44 and CD62L (CD4 gated) surface phenotypes of inguinal lymph node cells from wild-type and scurfy mice. Cells were isolated from CTLA4-Ig–injected scurfy mice at day 22 (d22) and day 48 (d48) after birth. As a control, data from phosphate-buffered saline–injected scurfy mice at day 22 are shown.