After intraperitoneal injection of CTX, the levels of TNF-α, IL-2, and IgG decreased significantly (P < 0.01), and after gavage with collagen peptides, the cytokine levels increased gradually, with no significant difference in the TNF-α and IL-2 levels in the CH group compared to the CK group (P > 0.05), indicating that the immunity levels in the CH group returned to normal values (Figure 5). Here, TNF is linked to cyclic hematopoiesis.