Limitations
There were some limitations to this study. First, this is a
single-center study and the sample size was not large, thus restricting
generalizability. Our data were used to observe the circulating Th17 and
Treg changes and the correlation between Th17/Treg ratio and length of
ICU stay. In addition, patients were included for sepsis as a variety of
risk factors, and our findings need to be confirmed by further studies
and more patients. Second, the change in functional immunocompetent
cells was only measured at one time point, because we aimed to
understand the early functional immune cells influence on clinical
outcomes. Many factors affect the length of hospital stay of patients
with sepsis, not all of them were observed. Therefore, further research
is necessary to include more factors that influence hospital stay length
of sepsis patients. Finally, Due to the cost and experimental
conditions, we did not purify CD4+T lymphocytes from human PBMC, nor did
we conduct further mechanism verification. CD28 knockout mice were not
used in our in vivo study for verification, and the intervention only
used CD28 antibody, and CD28 agonist was not used. As for the mechanism
of the effect of CD28 antibody on T cell function, we only focused on
the splenocytes’ apoptosis, but did not further explore other possible
mechanisms.