β1 and β7 integrins are not essential for normal T-cell development. Single-cell suspensions from thymus of control and β1β7 mutant BM chimeras 2 months after polyIC injection were prepared, stained with antibodies against CD4, CD8, and β1 integrin, and analyzed by FACS. (A) The dot blots show a representative staining of DN, DP, CD4SP, and CD8SP thymocytes for both control and β1β7 mutant BM chimeras. (B) A representative histogram displays β1 integrin expression on DP T cells of control (filled) and β1β7 mutant (line) mice. (C) Single-cell suspensions from spleen of control and β1β7 mutant BM chimeras 6 months after polyIC treatment were prepared, stained with CD4-FITC or CD8-FITC antibody, and subsequently sorted using anti-FITC MACS beads. FACS analysis of the CD4⁺- or CD8⁺-enriched fraction indicated higher than 95% purity (representative histogram is shown). DNA was prepared from MACS-enriched CD4⁺ or CD8⁺ splenocytes and analyzed by Southern blot and densitometrically evaluated. The bar graphs show the relative amount of CD4⁺ or CD8⁺ cells deficient for a functional β1 integrin gene. Error bar shows the standard deviation (n [control BM chimera]/[β1β7 mutant BM chimera]: CD4⁺, 3/3; CD8⁺, 4/4).