Question

Predict three ways that the normal defense system in the body can fail.

Answer 1

Prediction of three ways that human defence system can fail:

Consideration of interrelationships to the analysation of patients with suspected immune deficiency. They are mainly,

1. Specific adaptive immune responses are mediated by developmentally independent, but functionally interacting, families of lymphocytes.

2. T Lymphocytes mediate cellular immunity, while B lymphocytes and their plasma progeny produce antibodies to provide humoral immunity.

3. The activities of B and T cells and their products in host defence are closely integrated with innate immune functions of other cells of reticulo endothelial system.

4. Macrophages also become effector cells especially when activated by cytokines products of lymphocytes.

5. Immune deficiencies primarily involving T cells are usually associated with abnormal B cell function.

Clinical Disease features common to Immune Deficiency: we cal also predict by the following clinical features, host defence mechanism being failed,

1. Immunodeficiency syndromes whether congenital, acquires or iatrogenic,

2. Unusual susceptibility to infection,

3. Auto immune disease and lymphoreticular malignancies.

  The type of infection often provide the first clue to the nature of the immunologic defect.

Defects in Humoral Immunity: patients may have recurrent or chronic sinopulmonary infection, meningitis and bacteremia most commonly caused by pyogenic bacteria.

- these pyogenic bacteria also cause frequent infections in individuals who have either neutropenia or a deficiency of the pivotal third component of complement C3,

- the tripartite collaboration of antibody, complement and phagocytes in host defence against pyogenic organisms makes it important to assess all three systems in individuals with unusual susceptibility to bacterial infections.

Cell mediated Immunity: Antibody deficient patients in whom cell mediated immunity is intact have an interesting response to viral infections,

Laboratory evaluation of Host Defence status:

1. Initial screening assays,

- CBP with differential smear,

- Serum immunoglobulin assays.

2. Immunofluoroscence assays:

3. T cell functional evaluation,

4. B cell functional evaluation,

5. Complement assays,

6. Phagocyte function.

The classification of immune deficiency disorders are,

1. Primary immune deficiency syndromes,

2. Secondary immune deficiency syndromes,

   Due to failure of defence mechanism the immuno compromised patients will get frequent infections like:

1. HIV type-1,

2. Opportunistic infections,

3. Cytomegalovirus infection,

4. Mycobacterium tuberculosis,

5. Candida species,

6. Crypto coccus neoformans and

7. Histoplasma capsulatm infections.

Summary of the topic: There is mainly three predict ways to know the failure of host defence mechanism, mainly persons who will get frequently infected by bacteria, virus and fungi and auto immune disorders or failure of T cell or B cell functions.