Although it may be rationalized that this was expected based on T cell’s central role in HP, it should be noted that our findings contrast with those from Denis et al. [3] where injection of anti-Thy1.2, anti-CD8, or anti-CD4 antibodies failed to reduce absolute BALF cell numbers a similar model of HP, the anti-Thy1.2 even causing a surge in neutrophils. Here, CD4 is linked to hypersensitivity pneumonitis.