When analyzing the relative content of CD4+CD25+ lymphocytes, it was found that after 3 days in animals with acute pneumonia, there was a statistically significant 3.6-fold decrease in the proportion of regulatory T cells compared with the control (0.7% vs. 2.5%; p = 0.041), suggesting significant down-regulation of the Treg axis of the immune response in the acute phase of inflammation. Here, CD4 is linked to pneumonia.