It seems that the limitation of the recognition and presentation of antigens, expressed in a statistically significant decrease in the number of CD4+ and CD8+ T cells in the immediate vicinity of the introduced product, shown in prospective histopathological studies in patients suffering from Hashimoto’s disease, is the basis for the safety of PEGylated hyaluronic acid fillers recorded in long-term retrospective observations also in this group of patients. Here, CD4 is linked to Hashimoto thyroiditis.