## 4 Discussion
CPA-induced cytotoxicity releases damage-associated molecular patterns that activate splenic immune cells, leading to proliferation and increased splenic size [43]. Additionally, the spleen may act as a compensatory site for hematopoiesis in response to CPA-induced damage to the bone marrow, further contributing to its enlargement [44]. The absence of a significant decrease in spleen size in the PMT-treated groups suggests that PMT does not directly mitigate CPA-induced reactive splenic hypertrophy (Supplementary Figure S2). Instead, the effects of PMT appeared to be more pronounced in protecting the thymus, as evidenced by the restoration of thymus size, weight, and structure. This indicates that the immunomodulatory effects of PMT may be more effective in modulating adaptive immunity (T cell recovery) than in preventing splenic hypertrophy, which is driven by innate immune responses and hematopoietic compensation. Furthermore, T lymphocytes were significantly depleted in CPA-treated mice, reflecting profound immunosuppression. PMT treatment significantly increased the percentages of CD3e\({}^{+}\)CD4\({}^{+}\) T helper cells and CD3e\({}^{+}\)CD8\({}^{+}\) T cytotoxic cells, with the PMT200 group showing the most pronounced recovery. Moreover, immunohistochemical analysis revealed a significant increase in CD3+ lymphocyte levels, indicating enhanced T cell activity. The ability of PMT to enhance IL-10 expression and support thymic recovery is particularly noteworthy, as these effects are critical for maintaining immune homeostasis, particularly in the context of T cell-mediated immunity. PMT is a traditional herbal formula composed of 14 medicinal herbs, each containing bioactive compounds with distinct immunomodulatory properties. These compounds regulate cytokine production, macrophage activation, T cell differentiation, and inflammatory signaling pathways, contributing to PMTs immunoregulating potential. Key components include decursin (_Angelica gigs_) and ligustilide (_Ligusticum officinal_), which suppress proinflammatory cytokines and enhance T cell function [45; 46; 47; 48]. Paeoniflorin (_Paenonia japonica_) and catalpol (_Rehmania glutinosa_) regulate immune homeostasis by modulating inflammatory pathways such as MAPK/NF-kB and TLR-4 [49; 50; 51; 52]. Ginsensoides (_Panax ginseng_) maintain the Th1/Th2 balance [53; 54], while astragaloside IV (_Astragalus mongholicus_) enhances immune responses with anticancer potential [55; 56]. Pachymic acid (_Poria cocos_) and glycyrrhizin (_Glycyrrhizia uralensis_) play protective roles in inflammation and sepsis by inhibiting NF-kB and caspase-11 activation [57; 58; 59]. Other notable immunomodulators include bornyl acetate (_Amomum villosum_) and atractylenolide (_Attractylodes macrocephala_), which suppress the NF-kB/MAPK pathways, controlling inflammatory cytokine production [60; 61; 62]. Gallic acid (_Dimocarpus longan_) regulates the Th17/Treg balance, contributing to autoimmune disease management [63]. Lycium barbarum polysaccharides from _Lycium chinense_ stimulate macrophage activity and cytokine production [64], while flavonoids (_Crataegus pimattifida_) exhibit antiviral and immune-enhancing properties [65]. 6-Gingerol (_Zinggiber officinal_) has been shown to activate p38 MAPK and NF-kB, promoting Th1/Th17 responses while suppressing LPS-induced inflammation [66]. Collectively, these bioactive compounds contribute to PMT's synergistic immunomodulatory effects, making it a promising candidate for treating immune-related disorders. Further studies are needed to explore their precise mechanisms and combined therapeutic potential. While PMT treatment enhanced T cell populations, this study did not assess functional aspects such as antigen-specific responses, cytokine secretion, or T cell proliferation. Future studies should incorporate functional immune assays to better understand how PMT restores adaptive immunity. Although PMT significantly improved thymic recovery, it did not directly mitigate CPA-induced splenic hypertrophy.