Figure 1.

T cells are required for muscle regeneration. (A) FACS analysis of CD4⁺ and CD8⁺ T lymphocytes in the TA muscle or the spleen on day 3 after CTX-induced muscle injury. The total number of CD4⁺ or CD8⁺ cells is indicated on top of each panel. The percentage of CD4⁺ or CD8⁺ cells is indicated in parenthesis. The change of CD4⁺ and CD8⁺ T lymphocyte cell number was statistically significant after CTX injection in muscle. ^* indicates statistically significant, P < 0.01. The percentage changes were not statistically significant. Statistical analysis is based on 3 independent experiments. K indicates 10³ cells. M indicates 10⁶ cells. (B) The total number of CD3⁺, CD4⁺ and CD8⁺ T cells infiltrating into the TA muscle on various days post injury. Error bars are based on 3 independent experiments. (C) Representative HE staining of muscle sections on days 3, 7 and 12 after CTX injection in wild-type or Rag1^−/− mice. Scale bar, 200 μm. (D) Activated T or B lymphocytes were injected into the TA muscle of Rag1^−/− mice right after CTX injection. Muscle regeneration was monitored by HE staining 7 days post injury. Scale bar, 200 μm. (E) Statistical analysis of number of myofibers containing centrally located nuclei per visual field. Error bars are based on 3 independent experiments. ^**P < 0.01P < 0.05. (F) Statistical analysis of the myofiber size 12 days post injury. The graph is based on the average myofiber area distribution from 3 independent experiments. See also Supplementary information, Figures S1 and S2.