Physical Barrier
Skin
Physical Barrier
Mucus coating of epithelium lining respiratory, gastrointestinal and urogenital tracts
Physiological Barrier
Stomach acid
Physiological Barrier
Saliva
Physiological Barrier
Tears
Cellular Barrier
PMNL-neutrophils (WBC)
Cellular Barrier
Monocytes
Cellular Barrier
Natural killer (lymphocyte)
Cytokine Barrier
Interferons