Oral Intake of Semi-refined Carrageenan by Rats Affects Apoptosis of Lymphocytes

Introduction. The safety of generally recognized as safe food additives E407 and E407a is under rigorous debate. The aim of our research was to evaluate the effects of the orally administered food additive E407a (semi-refined carrageenan) on the viability of lymphocytes and their cell death modes. Methods. Totally, 16 adult WAG rats were divided into two equal groups (experimental – oral intake of 140 mg/kg of E407a during 2 weeks; control – oral consumption of drinking water instead). Blood samples were used to obtain leukocyte suspensions stained with Annexin V-FITC and 7-aminoactinomycin D (7-AAD). The region of lymphocytes was analyzed after collecting data using a BD FACSCanto™ II flow cytometer. Results. Oral administration of E407a led to a decrease in the amount of viable (Annexin V-, 7-AAD-) circulating lymphocytes. Furthermore, exposure to semi-refined carrageenan resulted in an elevated number of early apoptotic (Annexin V+, 7-AAD-) lymphocytes. Their percentage was approximately 4 times higher in rats exposed to E407a compared with the control group. Conclusion. Our findings indicate that dietary intake of E407a promotes apoptosis of circulating lymphocytes. Keywords: processed Eucheuma seaweed, annexin V, 7-aminoactinomycin D, flow cytometry.