Immunology Chapter 21 Richard L. Myers, Ph.D. Department of Biology Southwest Missouri State Temple Hall 227 Springfield, MO Homepage:

Immunodeficiency diseases Result from abnormalities of the immune system Clinically, patients suffer from frequent infections caused by normal flora Disease may result from –primary congenital defect –acquired from a secondary cause such as a viral or bacterial infection

Phagocytic deficiencies Defects arise from –reduction in numbers of phagocytic cells –reduction in function of phagocytic cells Resultls in recurrent bacterial or fungal infections –caused by Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Pseudomonas, Candida and Aspergillus

Reduction in neutrophil count Agranulocytosis is complete absence of cells Granulocytopenia (neutrophenia) is a reduction in blood neutrophils Congenital agranulocytosis is a disease where stem cells do not differentiate into mature neutrophils

Defective phagocytic function Adherence defects –leukocyte-adhesion deficiency (LAD) Chemotactic defects –lazy-leukocyte syndrome Killing effects –chronic granulomatous disease (CGD)

Humoral deficiencies X-linked agammaglobulinemia (XLA) –an X chromosome defect that involves maturation of pre-B cells to mature B cells X-linked hyper-IgM syndrome –B cells express membrane-bound IgM or IgD but not IgA, IgE or IgG Common variable hypogammaglobulinemia (CVH) –B cells do not mature into plasma cells

Cell-mediated deficiencies DiGeorge syndrome –characterized by the absence of a thymus –nude mice provide a model system –there is a severe decrease in the number of T cells

Combined immunodeficiencies Reticular dysgenesis –both lymphoid and myeloid stem cells fail to differentiate Bare-lymphocyte syndrome –results in deficiencies in expression of MHC molecules Severe combined immunodeficiency disease –marked decrease in T and B cells

It is only the ignorant who despise education Publius Syrus, 42 B.C.