Skin Immune Defense: Leukocytes in the Dermis and Hypodermis

Reticular connective tissue in the dermis and hypodermis houses leukocytes (white blood cells) that defend against infection via:

1. Phagocytosis (neutrophils, macrophages).
2. Antigen presentation (dendritic cells → T cells).
3. Antibody production (B cells/plasma cells).
4. Inflammation (chemokines, cytokines recruit effectors).
5. Cell-mediated immunity (cytotoxic T cells kill infected cells).

These coordinated responses eliminate pathogens and maintain skin homeostasis.