Development of the immune system in children.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000818:Animals; D002473:Cell Wall / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D006168:Guinea Pigs; D006801:Humans; D007107:Immune System / Q000254:growth & development*; D007070:Immunoglobulin A / Q000032:analysis; D007071:Immunoglobulin A, Secretory / Q000032:analysis; D066298:In Vitro Techniques; D007223:Infant; D007962:Leukocytes / Q000276:immunology; D008213:Lymphocyte Activation; D009297:Nasal Mucosa / Q000276:immunology / Q000378:metabolism; D013297:Streptococcus pyogenes / Q000276:immunology
D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory