IMMUNITY V
Immunodeficiency Diseases: Primary Immunodeficiency Diseases: Inherited immunodeficiency diseases may affect one or multiple components of immune system including B - cells, T- cells, macrophages, NK cells & complement. They are characterized by increased susceptibility to infection & often an increased incidence of autoimmunity, malignancy & elevated level of IgE.Examples: 1. B - cells: * X-Linked agammaglobulinemia (no antibody , loss of B cell specific tyrosine kinase), increased susceptibility to extracellular bacteria. ** Selective IgA deficiency, no IgA increased susceptibility to respiratory infection. 2.T - cells: Di George's Syndrome: * Loss of T cell : Thymic aplasia. ** Increased susceptibility to bacterial & viral infections.
3. B & T - cells: * Severe combined immunodeficiency ** Defective cytokines (e.g. X Linked SCID) lead to Increased susceptibility to bacterial, viral & other pathogenic infections. 4. Complement: Defect in specific complement component if late will lead to increased susceptibility to pyogenic infection as neisseria, but if there is an early deficiency of complement this will lead to autoimmune diseases & infections.
mediated by chemokine receptors such as CCR5 & CCR2. Persistent infection follows & through the depletion of CD 4 T- cells & an accompanying reduction in antibody and cytotoxic T - cells responses, immunity decreases and the host becomes more susceptible to opportunistic infections, In addition, loss of effective immunity may occur from generation of viral escape mutants & modification of amino acid sequence.