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.