Tuberculosis is caused by the bacterium Mycobacterium tuberculosis. It spreads through inhaling droplets from infected individuals and is able to survive inside macrophages. A cell-mediated immune response involving CD4+ T cells is required for immunity against the infection. CD4+ T cells activate macrophages to wall off the bacteria in structures called granulomas or tubercles. Cytokines released destroy nearby tissue, which can lead to caseous lesions. While most infections are controlled, some progress to more severe disease as the immune response damages tissues.

1. Immune
response to
tuberculosis
DONE BY
MANOVINA.M

2. Tuberculosis
 Principal causative agent:
 Mycobacterium tuberculosis
 Organism spreads easily and causes
pulmonary infection that results in
inhalation of small droplets containing few
bacilli

3.  The organism able to survive and multiply
intercellularly by inhibiting formation of
phagolisosomes.
 The infected macrophages lyses and releases large
number of bacilli.
 A cell mediated response involving CD4+T cells are
required for immunity .

4. Mode of action
 CD4+T cells are activated within 2-4 days
of infection they secrete cytokines that
Leads to infiltration of large number of
activated macrophages.
 These cell wall of the organism inside a
granuloma called Tubercle.

5. Tubercle formed in pulmonary
tuberculosis

6.  The localized concentrations of lysosomal enzymes in
these granulomas Can cause extensive necrosis.
 Massive activation of macrophages releases
concentrated lysosomal enzymes that are Released to
destroy healthy tissues nearby leading to formation on
circular region by necrosis that may develop into a
caseous lession ( cheesy consistency ).

7.  As these lesions heal they become calcified and
leave a scar that becomes visible on the x-ray of the
lungs as the defined shadow they are called as
Ghon complexes.
 Much of the tissue damage is due to the cell
mediated immune response because the activated
macrophages suppress the phagocytosed bacilli that
leads to infection.

9.  Cytokines produced by CD4+Tcells (TH1subset)
activates Macrophages so that they are able to kill the
bacilli or inhibit their growth.
 The role of INF alpha in immune response has been
demonstrated with knockout mice lacking INF alpha
these mice died when infected with attenuated strain
of mycobacteria.

10.  The INFalpha+ normal mice survived .
 The CD4+ T cell mediated immune response
mounted by majority of the people Gets controlled
to the infection and also reinfection.
 About 10% disease progress and leads to activation
of CD4+T cell and macrophages leads to granule
formation.

11.  Eventually the lesions rupture And the bacilli
dessiminate in the lungs And spread through blood and
lymphatic vessels To the plueral cavity ,bone, urogenetal
systems, meninges and peritoneum or skin.
 Tuberculosis has been traditionally treated by different
antibiotics for long period.

12. Treatment
 Drugs includes,
 Isoniazid
 Rifampicin
 Streptomycin
 Pyrazinamide
 Ethambutol

13. Vaccine
 Michael badtrains of mycobacterium bovis Called BCG
(bacillus calmetteguerin).
 Effective against extra pulmonary tuberculosis but less
against Common pulmonary tuberculosis.
 But after this vaccine the skin detection test cannot be
done so this vaccine is not widely used.
 The emergence of antibiotic resistant strain has been
developed for tuberculosis.