TRBC1 and infection: However, TCRβ−expressing CD11bhighCD14+F4/80+ macrophages increased significantly over the course of a Pb−A infection; in ECM susceptible C57BL/6 mice, the number of TCRβ−expressing CD11bhighCD14+F4/80+ macrophages increased 6.5 fold (p<0.01, Mann Whitney U test) from day 2 (2.2 x 105) to day 4 (1.4 ± 0.5 x 106) post-infection and the percentage of CD11bhighCD14+F4/80+ macrophages that express TCRβ was maximal (87.0 ± 3.6%) on day 6 post-infection when mice were exhibiting symptoms of ECM.