The effects of melamine on humoral immunity with or without cyanuric acid in mice

- Ingestion of melamine and cyanuric acid caused a lower content of CD138+.
- Ingestion of melamine and cyanuric acid suppressed the production of sIgA and C3.
- Melamine-related toxicity suppressed the production of IL-21, IL-6, IL-4 and IL-10.
- Melamine-related toxicity suppressed gata-3 and blimp-1 protein expression.
- Ingestion of melamine and cyanuric acid had certain humoral immunotoxicity.

Melamine is an industrial chemical with high nitrogen content. When added to the pet food and milk it can falsely elevate the apparent protein concentration readings. Cyanuric acid related structurally to melamine has a strong mutual affinity with melamine. The combined ingestion of melamine and cyanuric acid was considered to be responsible for the crystalluria, kidney stones and subsequent renal failure in animals. In our previous investigation, we demonstrated that melamine alone or its combination with cyanuric acid appears to be toxic to the immune system in mice. The objective of this study was to investigate the potential effects of melamine on humoral immunity with or without cyanuric acid in mice. In comparison to control group, a significantly lower content of plasma cells expressing CD138 were observed in mixture groups of melamine and cyanuric acid with both middle and high doses. The co-administration of melamine and cyanuric acid resulted in a significant decreasing in blimp-1 protein expression and the contents of sIgA, C3, IL-21 and IL-4 compared with the control group. Moreover, our data clearly showed that melamine-related toxicity suppressed the production of IL-6 and IL-10 in a dose-dependent manner. Also, the animals from mixture of melamine and cyanuric acid with high dose group exhibited a significantly lower expression of gata-3 protein, The results from the present study suggested that the exposure to melamine alone or combination with cyanuric acid had certain humoral immunotoxicity in mice, especially when ingested in high dosage.