Adaptive Immune Defenses

 While the passive immune system creates barriers and provides general antimicrobial defenses, the adaptive immune system is able to become activated by the presence of a pathogenic target and increased inflammatory signaling, indicating the presence of an infection (Iwasaki & Medzhitov, 2015).
      
    The adaptive immune system includes many antimicrobial responses including activation of B-cells to generate pathogen-specific antibodies and activation of T-cells to target the pathogenic species and further activate macrophages to clear the microbial pathogen.
    
    These defenses typically take one to two weeks to fully activate following the introduction of a specific pathogenic species and the start of an infection.
    For example, C. albicans colonization of the oral cavity is mostly held in check by the adaptive immune system (Richardson & Moyes, 2015).
    
    Dendritic cells are positioned beneath mucosal tissue and are activated by chemokines and antimicrobial peptides, including beta-defensin, secreted by epithelial cells responding to infection. The dendritic cells target C. albicans using pattern recognition receptors that respond to specific protein signatures on the fungal cells.
How T cells are formed
Dendritic cells are a type of antigen-presenting cell, and when they interact with C. Albicans, they present the fungal cell surface markers on their own membranes allowing the subsequent activation of T-cells (Richardson & Moyes, 2015).

Cause of Microbial Strain
On their own, these adaptive immune responses are able to resolve most viral, bacterial, and fungal infections; however, immunocompromised individuals are less able to combat these infections, and certain microbial strains or more virulent species can require additional medical intervention even in immunocompetent individuals.