[Defense mechanisms of the respiratory tract].
D001424:Bacterial Infections / Q000276:immunology*; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis; D009113:Muramidase / Q000032:analysis; D012141:Respiratory Tract Infections / Q000276:immunology*; D013183:Sputum / Q000276:immunology
D007071:Immunoglobulin A, Secretory; D009113:Muramidase