Immunodeficiency disorders occur when the immune system is impaired or absent, resulting in increased susceptibility to infection. Primary immunodeficiencies are congenital and caused by genetic defects, while secondary immunodeficiencies are acquired through other diseases, malnutrition, or HIV infection. Clinical manifestations of primary immunodeficiencies include infectious diseases, autoimmune disorders, malignancies, anemia, thrombocytopenia, and recurrent respiratory infections. The document further categorizes immune deficiencies based on defects in B cells, T cells, or both, and describes the roles and activation of the complement system in enhancing immune responses.

1. IMMUNODEFICIENCY
DISORDERS
SUDESHNA BANERJEE DUTTA
LECTURER S.R.S.V.M CON

2. Immunodeficiency Disorders
➢ Defect or impairment in immune function
IMMUNODEFICIENCY:
▪ The immune system’s ability to fight against infectious
diseases is completely absent or compromised (not
adequate).

3. Types
➢ Primary: Usually congenital, resulting from genetic
defects in some components of the immune system.
➢ Secondary (Acquired): As a result of other diseases
or conditions such as:
✓ HIV infection
✓ Malnutrition

4. Clinical Manifestations (Primary)
➢ Infectious diseases
➢ Autoimmune diseases (SLE, Psoriasis)
➢ Malignant disorders
➢ Anemia, Thrombocytopenia
➢ Recurrent respiratory infections.
➢ Diarrhea and mal-absorption

5. Categories of immune mechanisms
❖ B cell mediated immunodeficiency: Caused by improper
production of one or all of the immunoglobulins. Results in
increased infection from staphylococcus, pseudomonas,
streptococcus etc.
❖ T cell mediated immunodeficiency: Caused by defects in T
cell development both CD4 (Helper cell) & CD8 (killer cell)
Children rarely survive.
E.g. Di George syndrome: under development of thymus
gland

6. Categories of immune mechanisms
❖ Combined T cell & B cell immunodeficiency:
➢ Severe combine immuno-deficiencies (SCID): Caused
by diverse genetic mutation resulting in the absence of all
immune function.
Infants with this disease lead a short life with chronic
infections.

7. Categories of immune mechanisms
❖ Complement system (classical pathway):
❖ C3
Ag + Ab
complex
C3a
C3b C5
C5a
C5b
CELL
PERFORATION
& LYSIS
C5b6789
(membrane
attack
complex)
MAC
Activates
Macrophage &
helps in
PHAGOCYTOSIS

8. Complement system (classical pathway)
➢ Over 30 proteins makes up the complement sytem.
➢ It enhances the ability of antibody & phagocytic cells to destroy the
micro-organisms.
➢ It consists number of small proteins found in blood, synthesized in
liver & circulate as inactive precursors.
➢ When stimulated by any micro-organisms, the cytokines are released
& complement system gets prepared by activating the cell killing MAC.
➢ The end result of this system activation is stimulation of phagocytes to
clear the foreign materials.

9. Lab investigations
➢ TLC & DLC
➢ Lymphocyte count
➢ ESR
➢ Platelet count

10. Secondary immunodeficiency disorders
➢ AIDS
➢ Immuno-supression due to use of steroids
➢ Effect of ageing on immune competence
➢ Immuno-supression in transplant patients

11. Causes (secondary)
➢ IV drug abuse
➢ Unsafe sexual activity
➢ Chronic disease
➢ Steroids