CD4 and schizophrenia: In addition, the TLR4 signaling pathway promotes the secretion of IL-12 (88) and induces the differentiation of naive CD4+ T cells towards the Th1 lineage through the STAT4 signaling pathway (89), which may lead to Th1/Th2 imbalance, causing abnormal immune responses and subsequently affecting the function of the nervous system, related to the occurrence and development of schizophrenia (90).