Th17 cells
ANERGY
Causes of anergy or negatives tuberculin test:
CYTOLYTIC or CYTOTOXIC T-LYPMPHOCYTES
- like CD8 T cell
Nramp (natural resistance assoc. Macrophage protektahan)
TB responsed and course
TB bacilli -> alveoli -> alveolar macrophages
Can evade intracellular killing mechanism -> Get carried to lymph Nodes and other organs.
In lungs macrophages introduce antigens to T cells -> resulting in its expansion, Development of memory Tcell of which DTH cells may be a subset -> may result tuberculin positive persistence and/or long term Protection.
Inflammatory Th1 responses -> local pulmonary infiltrates and hilar Adenopathy (PRIMARY COMPLEX).
If unable to contain: cause progressive dse -> imbalance between proinflammatory and immunosuppressive effects -> military TB
Development of progression TB occurs in ___ % of affected individuals?
10%
Patent TB infection
LTBD
Factors that prompte Development and Ma Inten ace of latency?
Maintaned in Latent phase:
Reactivation of TB occurs at extrapulmonary site without apparently lung lessons in ___ % of affected individuals?
15%
Leads to reactivation due to depression of cell mediated immunity:
What age is particularly susceptible to Develop TB and are at increased risk of developing disseminated dse, particularly TBM.
Under 2yrs of age
Reason: weaker innate and adaptive responses / immaturity of immune system
Congenital infection identified possible reasons for the Development of dse:
TB source:
- environmental factors: overcrowding, poot Ventilation
Risk factors for TB:
AEI
Infectivity of smear positive vs smear negative household exposure?
60 to 80%
30 to 40%
TB morbidity with Family history exposure
2.5 Times than without knowing exposure
Additional groups at high risk of exposure and infection?
TB transmission and portal of entry:
Perinatal transmission of TB occur:
TB incubation period:
3 to 12 weeks
Shorter when the inoculum is large
Primary infection
Pathogenesis
Inhalation —> scavenging noon-activated, alveolar macrophages ingest the tubercle bacilli —> if not inhibited (virulance, microbicidal ability of macrophages) —> unrestrained replication —> some macrophages carry bacilli from lung to regional (hilar and mediastinal) lymph nodes —> disseminated via lymphatics or bloodstream (kidney, meninges, epiphyseal plates of long bones, vertebrae, apical segments of the upper lobes lungs) —> infected macrophages present tuberculous antigens to T lymph —> T-lym sensitized —> produce progeny —> secrete lymphokines (IFN-y, TNF) and activates macrophages —> inc lyrics enzyme (epitheloid macrophages, langhans giant cells)
CMI and DTH both inhibit the inc in Number of bacilli