Innate immune cells at injection site

Innate immune cells at the injection site encompass a variety of myeloid cells, such as neutrophils, monocytes, macrophages, and dendritic cells, that are the first to respond to the administration of vaccines or injectable therapeutics. Upon injection, these cells are recruited from the blood and surrounding tissues in response to local chemical signals and tissue damage (Liang et al., 2020). Their primary biological role is to detect foreign antigens and danger signals via pattern recognition receptors, subsequently processing these antigens for presentation to the adaptive immune system (Awate et al., 2013). In pharmaceutical development, this cell population is the primary site of action for adjuvants, which are designed to enhance the immune response by prolonging antigen persistence or stimulating specific cellular pathways (O'Hagan et al., 2017). While this activation is necessary for vaccine efficacy, it is also the source of common side effects known as injection site reactions, including localized inflammation and pain (Pulendran et al., 2011). Consequently, monitoring the behavior of these cells is crucial for evaluating both the immunogenicity and the safety profile of new injectable formulations.

Other names

Local innate immune responseInjection site leukocytesInnate immune cell population

Recruitment, activation, and maturation of innate immune cells (e.g., dendritic cells, macrophages) to facilitate antigen processing and the induction of adaptive immunity.