The frequency, severity, and location of the infection and thepathogens involved can help differentiate infections in a normalhost from infections in an immunodeficient patient (see Table 72-3). Although otitis media and sinopulmonary infectionsare common in children, recurrent infections, invasive or deepseeded infections, infections that require multiple rounds of oralantibiotics or need intravenous antibiotics, or infections with opportunistic infections suggest a primary immunodeficiency.Recurrent sinopulmonary infections with encapsulated bacteria suggest a defect in antibody-mediated immunity becausethese pathogens evade phagocytosis. Failure to thrive, diarrhea,malabsorption, and infections with opportunistic infections (i.e., fungi, Candida sp, Pneumocystis jiroveci [carinii]) suggest T-cell immunodeficiency. Recurrent viral infections can resultfrom T-cell or NK-cell deficiency. Deep-seated abscesses and infections with Staphylococcus aureus, Serratia marcescens, and Aspergillus suggest a disorder of neutrophil function, such as chronic granulomatous disease (CGD). Delayed separation ofthe umbilical cord, especially in the presence of omphalitis andlater onset periodontal disease, in addition to poorly formedabscesses, indicates leukocyte adhesion deficiency.
Age of onset of symptoms can be helpful in defining animmune deficiency, although significant variability does occur. Neutrophil defects (e.g., congenital neutropenia, leukocyte adhesion deficiency) typically present in the first severalmonths of life. Antibody defects (e.g., agammaglobulinemia)and T-cell defects (e.g., severe combined immunodeficiency[SCID]) typically present after 3 months of life after maternal antibody levels have waned. Presentation with symptomsof an antibody deficiency in adolescence or young adulthoodsuggests common variable immunodeficiency (CVID) ratherthan agammaglobulinemia, although milder phenotypes ofprimary immunodeficiency disease may not present until later
Table 72-2 Cytokines and Chemotactic Cytokines and Their Functions FACTOR SOURCE FUNCTION IL-1 Macrophages Co-stimulatory effect on T cells, enhances antigen presentation, acute phase response, fever IL-2 T cells Primary T-cell growth factor; B-cell and NK-cell growth factors; required for T regulatory cell function and survival
T cells, macrophages, Enhances immunoglobulin synthesis, antiviral activity, induces acute phase response, fever, fibroblasts, endothelium hematopoietic effects
IL-7 Stromal cells Enhances growth of pre-T cells
T cells, macrophages, Neutrophil-activating protein; T lymphocyte and neutrophil chemotactic factor epithelium
IL-9 T cells Acts in synergy with IL-4 to induce IgE production, mast cell growth
T cells, including regulatory Cytokine synthesis inhibitory factor; suppresses macrophage function; enhances B-cell T cells, macrophages growth; inhibits IL-12 production; suppresses inflammation at mucosal surfaces
Macrophages, neutrophils NK cell stimulatory factor; cytotoxic lymphocyte maturation factor; enhances IFN-γ synthesis; inhibits IL-4 synthesis
IL-17 T cells Induces IL-1β and IL-6 synthesis, important in fungal infections
TGF-β T cells, including regulatory Inhibits T-cell and B-cell proliferation and activation, induces T regulatory cells T cells, many other cells
RANTES T cells, endothelium Chemokine for monocytes, T cells, eosinophils
MIP-1α Mononuclear cells, Chemokine for T cells; enhances differentiation of CD4+ T cells endothelium