No association found between late‐onset inflammatory adverse events after soft tissue filler injections and the adaptive immune system

BACKGROUND: To date, it is unknown why some individuals develop late‐onset inflammatory adverse events after treatment with fillers. These events may result from various factors, including an immunological response of the adaptive immune system. OBJECTIVE: In a pilot study, we looked for evidence that is there a relation between late‐onset inflammatory adverse events and the presence of immune cells surrounding the injected filler. METHODS AND MATERIALS: We included 47 patients, of whom 20 experienced late‐onset inflammatory adverse events to different fillers (inflammatory group) and 27 who did not (reference group). A biopsy was taken from the area of the adverse event. Hematoxylin–eosin staining and immunohistochemistry analysis with CD3 (T‐cells) and CD68 (macrophages) on paraffin tissue sections was used to assess the biopsies. RESULTS: Immune cells were found in biopsies obtained from 18 of 47 patients: Nine biopsies from the inflammation group and nine from the reference group. All these 18 cases showed CD68‐positive immune cells. Virtually no CD3‐positive immune cells were found. CONCLUSION: Our results indicate that there is no T‐cell activity in biopsies from areas with late‐onset adverse events after filler injections. The macrophages found in the biopsies are probably not responsible for the inflammatory response.