FGF21 and pertussis: It plays a central role in regulating immune responses, promoting B cell proliferation and differentiation, enhancing antibody production, and inhibiting Th1-type immune responses.[26] Its causal role in pertussis may be related to its promotion of antibody generation and regulation of immune balance.[27] The findings related to IL-18R1 and FGF-21 are novel, particularly IL-18R1, IL-18R1 is the receptor for interleukin-18 (IL-18), an important pro-inflammatory cytokine involved in the immune system’s response to pathogens.