Page 473 - Clinical Immunology_ Principles and Practice ( PDFDrive )

454 ParT FOur Immunological Deficiencies

trait can sometimes be traced back to many generations. A social
history should be obtained for risk factors associated with
increased risk of acquiring HIV infection. Socioeconomic factors
often determine malnutrition, known to be of a significant impact
on immune function. 12

KEY CONCEPTS
Genetic Immunodeficiencies
• Diagnosis of genetic immunodeficiencies require high clinical suspicion
and confirmation with molecular studies.
• In a minority of cases, genetic immunodeficiencies might not present
with all clinical elements of classic descriptions. For example, patients
with Bruton agammaglobulinemia might have residual B-cell and
immunoglobulin production.

PHYSICAL EXAMINATION FINDINGS
The physical examination might provide findings that indirectly
address the immune system; for example, scarred bilateral tympani
suggest recurrent ear infections. More commonly, patients with
immunodeficiency might otherwise look like normal individuals, FIG 32.3 Severe gingivostomatitis and dental erosion in a 2-year-
unless severe infections had produced an organ damage or had old child with leukocyte adhesion defect (LAD). (Courtesy of Dr.
delayed growth and development. However, attention to details D.C. Anderson.)
in the physical examination may supply important clues that
suggest immune dysfunction. In a normal child, a paucity of
lymphoid tissue, such as tonsils and lymph nodes, might reflect age-specific ranges. Leukocytosis, neutropenia, lymphopenia, and
impaired development resulting from immune deficiency. This abnormalities in WBC morphology can be detected from this
is especially seen in patients with X-linked agammaglobulinemia. test. Persistent neutrophilia might suggest LAD. Anemia may be
Certain physical findings are suggestive of syndromic immuno- present in children with chronic disease. Platelet counts may be
deficiencies, such as with telangiectasia over the bulbar conjunc- abnormally low in children with poor bone marrow function or
tivae and face with or without ataxia in ataxia–telangiectasia autoimmune disease, and platelets will be reduced in number
(AT); chronic eczema and delayed shedding of primary teeth in and morphologically small in children with WAS. Chemistry
hyper-IgE syndrome (HIES); severe eczema in immunodeficiency, panels, including serum liver enzymes levels, might suggest organ
polyendocrinopathy and enteropathy, X-linked (IPEX) syndrome, compromise as a result of infections or autoimmunity associated
and WAS; chronic periodontitis in defects of the neutrophils; with immunodeficiency. Low protein levels suggest malnutrition
or silvery hair, pale skin, and photophobia in Chediak-Higashi and conditions associated with protein losses, which may cause
syndrome. Investigation for Shwachman-Bodian-Diamond hypogammaglobulinemia. Examination of the posteroanterior
syndrome (SBDS) should be considered in patients with neu- and lateral chest radiographs to look for a thymic shadow can be
tropenia, especially if they also present with skeletal dysplasia. helpful because its absence suggests impaired T-cell development.
Patients with DiGeorge syndrome and nuclear factor-κB (NF-κB) This is especially useful in infants because the thymus mass
essential modulator (NEMO) deficiency present with characteristic normally involutes with age. In addition, the thymus may shrink
facies. in response to such stresses as surgery, infection, or high-dose
Children with severe immune defects are small for their age, steroid treatment.
with growth delay secondary to recurrent infections. Hepato- HIV infection can be ruled out by screening with measurement
splenomegaly and diffuse lymphadenopathy might suggest HIV of anti-HIV antibodies, by the enzyme-linked immunosorbent
infection or a disorder of immune dysregulation. Children with assay (ELISA) or the rapid HIV test. In those individuals with
leukocyte adhesion defect (LAD) can present with severe gingi- suspected humoral immunity defect and in children younger
vostomatitis and dental erosion as a consequence of abnormal than 18 months of age, a polymerase chain reaction (PCR)–based
leukocyte function (Fig. 32.3). Multiple scars from skin abscesses test to detect HIV viremia should be performed to avoid false-
might suggest neutrophil defects, and scarred tympani with negative results and confounding maternal anti-HIV antibodies,
reduced hearing might indicate a history of recurrent otitis media, respectively.
which can be associated with antibody deficiency.
Immunology Testing
LABORATORY TESTING FOR IMMUNE FUNCTION Specific immunological testing is guided by clues obtained from
the history and physical examination and common screening
Results from commonly ordered tests might provide with a great laboratory tests.
deal of information about the immune system. The complete
blood count (CBC) with differential and platelet determination Serum Immunoglobulin Levels
is ordered to quantitate the total white blood cell (WBC) count The levels of IgG, IgA, IgE, and IgM can be measured in serum.
and total numbers of neutrophils, lymphocytes, eosinophils, The IgA level is especially helpful in that it is low in all permanent
and platelets. Abnormal counts should be determined by using types of agammaglobulinemia and in selective IgA deficiency.