General Considerations

• SS 1. It is critical to maintain a high index of suspicion for PIDDs in patients presenting with recurrent infections, autoimmune disease, malignancy, and combinations of these conditions (D).
• SS 2. Other conditions that can increase susceptibility to infection should be sought in patients with suspected PIDDs. (D)
• SS 3. It is important to confirm the precise focus of infection and organism when possible in any patient with known or suspected PIDDs. (F)
• SS 4. A focused family history (eg, recurrent infections, absence of infections in siblings, early childhood deaths, and diagnosed PIDDs) should be obtained when the differential diagnosis includes a PIDD. (D)
• SS 5. A stepwise approach is recommended to evaluate suspected PIDDs. (D)
• SS 6. Evaluation of specific immune responses is essential for diagnosis of PIDDs. (C)
• SS 7. PIDDs should be defined at the molecular genetic level if management can be affected. (F)
• SS 8. The possibility of an X-linked PIDD should be considered, even in female patients, when other possibilities have been ruled out. (D)
• SS 9. Carrier status should be determined for all potentially affected relatives of patients with severe PIDDs. (D)

Figure 1. General Approach for the Diagnosis of Primary Immunodeficiency

Table 1. Characteristic Clinical Presentations of Some Immunodeficiency Disorders

Diagnosis	Symptoms and/or clinical presentation
Combined Immunodeficiencies
SCID	Failure to thrive, diarrhea, severe/disseminated infections, opportunistic infections, rash; abnormal newborn screena
CD40L deficiency	Recurrent serious pyogenic infections, opportunistic infections (PCP)
Immunodeficiency syndromes
WAS	Thrombocytopenia with bleeding and bruising, eczema, recurrent infection with encapsulated organisms, autoimmunity
AT	Chronic sinopulmonary disease, cerebellar ataxia, oculocutaneous telangiectasia, malignancy
DGS	Hypocalcemic seizures caused by hypoparathyroidism, cardiac disease, abnormal facies, infection, abnormal newborn screena
Antibody deficiency	Recurrent sinopulmonary infections with encapsulated bacteria, recurrent viral respiratory tract and gastrointestinal infections
Immune dysregulation	Autoimmunity, lymphoproliferation, HLH
Phagocytic cell defects
CGD	Deep-seated infection, abscess with granuloma formation
LAD	Recurrent serious bacterial infections, delayed separation of the umbilical cord; poor wound healing, lack of pus
HIES type 1	Chronic dermatitis, recurrent serious infection of the lungs with pneumatoceles; skin infections, bone fragility, failure to shed primary teeth
MSMD	Severe mycobacterial and Salmonella species infections
Innate immune defects
NEMO deficiency	Severe bacterial infections, opportunistic infections, anhidrotic ectodermal dysplasia
IRAK-4 defect	Severe gram-positive bacterial infections in early childhood
CMCC	Chronic skin and mucous membrane fungal infections
HSE	Herpes simplex encephalitis
EV	Severe disseminated cutaneous papillomatosis
Autoinflammatory disorders	Episodic fever often associated with dermatitis, gastrointestinal symptoms, and arthropathy
Complement deficiency	Recurrent bacterial infections (encapsulated strains, Neisseria species), autoimmunity
Immunodeficiency associated with autoantibodies
Anti–GM-CSF autoantibodies	Cryptococcal meningitis and PAP (alone or together)
Anti–IFN-γ autoantibodies	Disseminated infections with mycobacteria, Salmonella species, Cryptococcus species, Histoplasma species, Penicillium species, and varicella-zoster virus

^a Many states are now screening for SCID (see SS 26). Some infants with DGS (and other disorders) might be detected by this newborn screening. See Table 11 for abbreviations.

Table 2. Laboratory Tests of Immune Function

Screening tests	Advanced tests
Humoral immunity
Serum immunoglobulin levels	Flow cytometry to enumerate B-cell subsets (eg, naïve and switched memory cells)
Serum specific antibody titers	In vitro immunoglobulin production in response to mitogens or other stimuli
Antibody response to booster immunization	Antibody response to immunization with ΦΧ174
Flow cytometry to enumerate total B cells
Cellular immunity
TREC newborn screening	Flow cytometry to enumerate T-cell subsets (eg, naïve, memory, and activated cells)
Flow cytometry to enumerate CD4 and CD8 T cells and NK cells	In vitro proliferative response to mitogens and antigens
Cutaneous delayed hypersensitivity	T-cell cytotoxicity
Spontaneous NK cytotoxicity	In vitro surface marker expression and cytokine production in response to stimuli
	Cytoplasmic protein phosphorylation in response to stimuli
Phagocytic cells
Blood cell count with differential	Chemotaxis and/or phagocytosis assay
Neutrophil staining, morphology on a peripheral blood smear	Enzyme assays (myeloperoxidase, G6PDH)
DHR reduction or nitroblue tetrazolium	WBC turnover
Flow cytometry for adhesion molecules	Bacterial or fungal killing
	Bone marrow biopsy
Complement
CH50 assay (total hemolytic complement activity)	Level or function of individual complement components
AH50 assay (alternative pathway hemolytic activity)
Lectin pathway function
Genetic tests
Microarray for copy number variation	Targeted gene sequencing
	Whole-exome/genome sequencing

Table 3. Summary of Laboratory Findings in the Diagnosis of Antibody Deficiencies

IgG	IgA	IgM	IgG subclass	Vaccine response	B cells	Diagnosis
NL	NL	NL	NL	NL	NL	Normala
NL	NL	NL	NL	Lowb	NL	SAD
NL	NL	NL	≥1 Low	Lowb	NL	IGGSD
NL	Absent	NL	Normal	NL or low	NL	SIGAD
NL	Absent	NL	≥1 Low	Lowb	NL	IgA deficiency with IGGSD
Low	NL	NL		NL	NL	Possible secondary, unspecified, or transient hypogammaglobulinemiac
Low	NL or low	NL or low		NL	NL or low	Unspecified or transient hypogammaglobulinemia
Low	Low	NL or high		Low	NL	HIM
Low	Low	NL or low		Lowd	NL or low	CVID, possible transient hypogammaglobulinemia
Absent	Absent	Absent			Absent	Agammaglobulinemia or severe CVIDe

The clinical presentation is primarily suggestive of an antibody defect or any evaluation of cellular function is thus far normal, and the clinical presentation is at least consistent with a possible antibody deficiency and not suggestive of a cellular component (e.g., lack of opportunistic infections). The initial laboratory examination of humoral immunity consists of measuring levels of various immunoglobulin isotypes (IgG, IgA, IgM, and possibly IgG subclasses) in serum, as well as a measure of function or specific antibody production, which should include both protein and polysaccharide antigens (see SS 6).
^a Consider complement deficiency or phagocyte defect.
^b Usually refers to polysaccharide response.
^c In this circumstance it is useful to measure serum total protein and/or albumin levels. If low, this is consistent with secondary hypogammaglobulinemia.
^d Protein and/or polysaccharide response.
^e Cellular immunity should be evaluated as indicated by other clinical features but is often worth considering when significant impairment of humoral immunity is observed because it could be a component of a CID.

Table 4. Summary of Therapeutic Considerations for Primary Immunodeficiencies and Their Complications

Diagnosis	IgGa	HSCT	Gene therapy
CIDs
SCID (IL2RG, ADA)	Yes	Yes	Yes	Avoid live vaccines: all PCP prophylaxis: all SCID, CD40, CD40L Blood products irradiated, CMV–: all ADA: PEG-ADA CD40, CD40L: G-CSF
SCID (other)	Yes	Yes	No
CD40L deficiency	Yes	Yes	No
Other CID	Yes	Many	No
Immunodeficiency syndromes
WAS	Yes	Yes	Yes	Avoid live vaccines: many Multidisciplinary care: many WAS: splenectomy DGS: thymus transplantation Immunomodulation as needed Chemotherapy as needed
AT	Some	No	No
DGS	Some	No	No
Other syndromes	Some	Some	No
Antibody deficiency
Agammaglobulinemia	Yes	No	No	Avoid live vaccines: agammaglobulinemia, CVID Antibiotics: all Splenectomy: CVID Immunomodulation: CVID Chemotherapy: CVID Pneumococcal vaccine: SIGAD, IGGSD, SAD
CVID	Yes	Rare	No
Other antibody deficiency	Yes	No	No
Immune dysregulation
FHL	No	Yes	No	Antimicrobials as needed Chemotherapy as needed Immunomodulators as needed
ALPS	No	Yes	No
IPEX	No	Yes	No
APECED	No	No	No
Other	Some	Some	No
Phagocytic cell defects
Neutropenia	No	Yes	No	Avoid live bacterial vaccines: all Antimicrobial prophylaxis: all IFN-γ: CGD Surgical or dental debridement: CGD, LAD-I Granulocyte transfusions: CGD, LAD-I G-CSF: neutropenias Fucose: LAD-II
CGD	No	Yes	Yes
LAD	No	Yes	No
HIES type 1	Some	Rare	No
MSMD	No	Some	No
Innate immune defects
NEMO deficiency, other NF-κB defects	Yes	Yes	No	Avoid live vaccines: NF-κB PCP prophylaxis: NF-κB Antimicrobial prophylaxis: NF-κB, CMCC G-CSF: WHIM syndrome Antiviral prophylaxis: HSE
CMCC	No	No	No
WHIM syndrome	Yes	Some	No
HSE	No	No	No
EV	No	No	No
Autoinflammatory disorders	No	No	No	Cytokine (IL-1, TNF, IL-6) inhibitors: CAPS, DIRA, PAPA, PSMB8, TRAPS Steroids: Blau syndrome, DITRA, HIDS, TRAPS Retinoids: DITRA Colchicine: TRAPS
Complement deficiency	No	No	No	Antibiotics: all Pneumococcal vaccine: C1, C2, C3, C4 Meningococcal vaccine: C5-C9 Immunomodulators: C1, C2, C4, factors H and I
Cytokine autoantibody-mediated disorders	Possible	No	No	Plasmapheresis Rituximab Cytokine supplement

^a Yes or No indicates whether or not IgG replacement is a component of standard therapy for this disorder.

Table 5. Regimens for Prophylaxis of Bacterial Respiratory Tract Infections

Antibiotic	Regimen for children	Regimen for adults
Oral agentsa
Amoxicillin (consider with clavulanate, if necessary)	10-20 mg/kg daily or twice daily	500-1,000 mg daily or twice daily
Trimethoprim (TMP)/ sulfamethoxazole dosing for TMP)	5 mg/kg daily or twice daily	160 mg daily or twice daily
Azithromycin	10 mg/kg weekly or 5 mg/kg every other day	500 mg weekly or 250 mg every other day
Clarithromycin	7.5 mg/kg daily or twice daily	500 mg daily or twice daily
Doxycycline	Age >8 y: 25-50 mg daily or twice daily	100 mg daily or twice daily
Inhaled agents
Gentamicin	Age >6 y: 80 mg twice daily, 28 days on, 28 days off, OR 21 days on, 7 days off
Tobramycin	Age >6 y: 300 mg twice daily, 28 days on, 28 days off

^a These are commonly used regimens. If these agents are not effective or are not tolerated, other drugs can be considered, including cefuroxime, cefprozil, cefpodoxime, ciprofloxacin or other quinolone, or others, depending on the individual circumstances of the patient.

Figure 2. Diagnosis of Combined or Syndromic Immunodeficiencies

Combined B- and T-Cell Immunodeficiencies

Severe combined immunodeficiency (SCID)

• SS 26. SCID should be considered in the differential diagnosis when an infant presents with recurrent, persistent, or severe bacterial, viral, or fungal infections or failure to thrive. (C)
• SS 27. Patients with SCID or suspected SCID should receive IgG replacement therapy. (C)
• SS 28. Patients with SCID or suspected SCID should be protected from exposure to infectious agents. (C)
• SS 29. Patients with SCID should receive PCP prophylaxis. (C)
• SS 30. Early signs of infection should be promptly investigated and antimicrobial regimens initiated and for prolonged periods. (C)
• SS 31. Polyethylene glycol (PEG)-conjugated ADA (PEG-ADA) should be administered to patients with SCID caused by ADA deficiency if HSCT or gene therapy is unavailable. (C)
• SS 32. A suspicion of SCID should be considered an urgent clinical condition. (C)
• SS 33. Patients with SCID should be immunologically reconstituted by means of HSCT or gene therapy. (B)

Table 6. Clinical and Laboratory Manifestations of Selected Combined Immunodeficiencies and Syndromes

Gene defect(s) or disease(s)	Clinical features	Laboratory features
Ca/Mg channel defects (MAGT1, ORAI1, STIM1)	Severe and opportunistic infections, autoimmune disease, anhydrotic ectodermal dysplasia, myopathy	Normal T-cell numbers, ↓ T-cell function
CARD11	Opportunistic infections	Hypogammaglobulinemia, normal lymphocyte numbers, ↓ T-cell function
CD27	Persistent symptomatic EBV viremia, recurrent infection	Hypogammaglobulinemia, impaired specific antibody response, decreased mitogen proliferation
CD3G	Variable severity, SCID or mild phenotype, autoimmune hemolytic anemia	Modest ↓ CD8 T cells, ↓ CD45RA+ cells, ↓ TCR expression, variable immunoglobulins
CD8	Recurrent bacterial respiratory tract infections, bronchiectasis	Absent CD8 T cells, ↑ double-negative T cells
CTLA4	Autosomal dominant, lymphoproliferation, organ infiltration, lymphoma, respiratory tract infections	↓ CD4 T cells, ↓ B cells, hypogammaglobulinemia, ↑ T-cell proliferation
CTPS1	Disseminated infections with EBV and varicella-zoster virus, encapsulated bacteria, B-cell lymphoma	Lymphopenia, ↓ naïve CD4 cells, ↓ IgG2, ↓ pneumococcal response, ↓ memory B cells, absent invariant NK T cells, ↓ PHA proliferation
FOXN1	Athymia, reduced T-cell numbers, absence of hair, and nail dysplasia	↓ Naïve T cells; ↑ double negative (CD4– CD8)– T cells
IKZF1	Prematurity, polyhydramnios with fetal hydrops, neonatal pancytopenia	Normal lymphocyte numbers, absent B cells, ↓ NK cells, ↓ CD45RO+ T cells, absent mitogen proliferations, ↓ IgG
IL21R	Respiratory tract infections, failure to thrive, diarrhea, cryptosporidiosis	Normal lymphocyte numbers, ↑ IgE, ↓ specific antibody, normal T-cell function, ↓ NK cytotoxicity
ITK	EBV-associated lymphoproliferation, lymphoma	Lymphopenia, hypogammaglobulinemia
MHC class I deficiency (TAP1, TAP2, TAPBP), CD8A	Variable severity, recurrent respiratory tract infections, bronchiectasis	Complete absence of CD8+ cells, normal CD4 cells, normal T-cell proliferation, normal immunoglobulins and antibody
MHC class II deficiency (MHC2TA, RFX5, RFXANK, RFXAP), and LCK mutation	Severe and opportunistic infections, diarrhea, malabsorption, failure to thrive	↓ CD4 T cells, normal CD8 cells; ↓ T-cell proliferation, hypogammaglobulinemia, ↓ antibody
NP	Severe and opportunistic infections, severe varicella (including vaccine strain), neurological impairment	↓ T cells, variable ↓ in B cells, ↓ T-cell proliferation, variable immunoglobulins and antibody
PGM3	Recurrent infections, skeletal dysplasia, developmental delay	Neutropenia, lymphopenia (↓ T and B cells), bone marrow failure
POLE1	Mild facial dysmorphism, livedo, short stature, recurrent pulmonary infection with bronchiectasis, recurrent Streptococcus pneumoniae meningitis, long-bone abnormalities	↓ IgM, ↓ IgG2, ↓ isohemagglutinin, ↓ CD27+ memory B cells, low naïve T-cell numbers
SLC46A1	Severe opportunistic infections, failure to thrive (reversible with folate administration)	Normocytic anemia, ↓ serum folate, hypogammaglobulinemia, ↓ T-cell proliferation
RHOH deficiency	Warts, molluscum, granulomatosis, Burkitt lymphoma	↓ CD4 T cells, normal immunoglobulins and antibody
STAT5B	Growth failure, ichthyosis/eczema, diarrhea ± bacterial or opportunistic infections, autoimmune disease	↓ Insulin-like growth factor, ↑ growth hormone, ↓ T cells, especially ↓ Treg cells
Trisomy 21	Cognitive impairment, characteristic facies, cardiac defects, gastrointestinal disorders, hypothyroidism, recurrent respiratory tract infections	Variable T- and B-cell lymphopenia, ↓ naïve T and B cells, IGGSD, poor vaccine response, ↓ in vitro T-cell proliferation, ↓ neutrophil chemotaxis
TRNT1	Sideroblastic anemia, periodic fevers, developmental delay, sensorineural hearing loss, cardiomyopathy, CNS abnormalities	Variable ↓ immunoglobulins, ↓ B cells, progressive ↓ T cells and NK cells
ZAP70	Variable severity, SCID, and opportunistic infections, failure to thrive, mild phenotypes	↓ CD8 T cells, normal CD4 cells, ↓ T-cell proliferation, hypogammaglobulinemia, ↓ antibody

Table 7. Lymphocyte Phenotype Classification of SCID

Disease	Genes
T–B–NK–
Adenosine deaminase	ADA
Adenylate kinase (reticular dysgenesis)	AK2
T–B–NK+
Artemis	DCLRE1C
Cernunnos	NHEJ1
DNA-dependent protein kinase	PRKDC
DNA ligase IV	LIG4
RAG1 and RAG2	RAG1, RAG2
T–B+NK–
X-linked SCID	IL2RG
JAK3 deficiency	JAK3
CD25 deficiency	IL2RA
T–B+NK+
CD3 complex defects	CD3D, CD3E, CD3Z
Coronin 1A deficiency	CORO1A
CD45 deficiency	PTPRC
IL-7 receptor deficiency	IL7RA

Other CID syndromes

• SS 34. Patients with CID with intermediate T-cell numbers and function should be studied for leaky SCID or one of several CID syndromes based on clinical and laboratory characteristics. (C)
• SS 35. All forms of ancillary or supportive therapy administered to patients with SCID should be considered for patients with leaky SCID or non-SCID combined immunodeficiency. (C)
• SS 36. Patients with leaky SCID or a non-SCID combined immunodeficiency should be considered for stem cell therapy or gene therapy on a case-by-case basis. (C)

Hyper-IgM syndrome (HIM) caused by defects of CD40L and CD40

• SS 37. The diagnosis of a form of HIM should be considered in patients with very low IgG, IgA, and IgE levels and normal or increased IgM levels. (C)
• SS 38. CD40L expression should be evaluated by using flow cytometric methods on activated T cells. (C)
• SS 39. CD40 expression should be measured by using flow cytometry on monocytes or B cells. (C)
• SS 40. Female patients with the HIM phenotype should be studied for CD40L mutation if the CD40 mutation or another known mutation associated with the HIM phenotype is not found. (C)
• SS 41. PCP prophylaxis is indicated for all patients with known or suspected CD40 or CD40L deficiency. (C)
• SS 42. Neutropenia in patients with CD40 or CD40L deficiency should be treated with granulocyte colony-stimulating factor (G-CSF). (C)
• SS 43. HSCT should be considered for CD40L and CD40 deficiency. (C)

CID, unspecified

• SS 45. Any patient with abnormal serum immunoglobulin levels, specific antibody production, or both and evidence of impaired cellular immunity who does not fulfill the clinical and laboratory diagnostic criteria for any of the above disorders should be given a diagnosis of unspecified CID. (D)

Well-Defined Syndromes with Immunodeficiency

• SS 46. A diagnosis of Wiskott-Aldrich Syndrome (WAS) should be considered in all male patients with clinically significant thrombocytopenia and small platelets. (C)
• SS 47. Patients suspected to have WAS should have a definitive molecular diagnosis by finding a known deleterious WAS mutation and/or abnormal WAS protein expression, which might be helpful for prognosis. (C)
• SS 48. Management of patients with WAS should include IgG replacement. (C)
• SS 49. HSCT must be seriously considered for patients <5 years of age with suitable stem cell donors. (C)

Non-SCID DNA repair defects

• SS 50. AT and other chromosomal repair disorders should be considered in all children with frequent infections and characteristic neurological, skeletal, and/or cutaneous manifestations, including ataxia, microcephaly, and telangiectasia. (C)
• SS 51. Immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome should be considered in patients with abnormal facies, developmental delay, and immunodeficiency. (C)
• SS 52. Postmeiotic segregation increased 2 (PMS2) defects should be sought in patients with dysgammaglobulinemia, cafe-au-lait spots, and colon and/or brain tumors. (C)
• SS 53. A diagnosis of radiosensitivity, immunodeficiency, dysmorphic features, and difficult learning (RIDDLE) syndrome should be suspected in patients with developmental delay, short stature, dysmorphic facies, and hypogammaglobulinemia. (C)
• SS 54. Cytogenetic abnormalities, such as chromosomal translocations and chromosome fragility, support a diagnosis of AT or other chromosomal repair disorders. (C)
• SS 55. Patients suspected to have AT should be screened by measuring the serum α-fetoprotein (AFP) level (C).
• SS 56. Imaging with radiography should be used cautiously in patients with AT or other chromosomal repair disorders. (C)
• SS 57. Antibiotic prophylaxis, IgG replacement therapy, or both are indicated for patients with AT or other chromosomal repair disorders with increased susceptibility to infections. (C)
• SS 58. Management of malignancy in patients with AT and related disorders must be individualized. (C)
• SS 59. Stem cell transplantation can be considered in selected patients with AT and related disorders. (C)

DiGeorge syndrome (DGS)

• SS 60. DGS should be investigated in patients with thymic hypoplasia, cardiovascular structural defects, midline craniofacial defects, and hypoparathyroidism. (C)
• SS 61. Periodic immunologic re-evaluation is recommended for patients with DGS. (C)
• SS 62. Patients suspected of having DGS should have molecular testing for deletion of chromosome 22q11.2 or 10p14-13 by using fluorescence in situ hybridization or a genomic DNA microarray. (C)
• SS 63. Treatment of infants with complete DGS requires some form of T-cell reconstitution. (C)

Idiopathic CD4 lymphopenia (ICD4L)

• SS 64. ICD4L should be suspected in patients with opportunistic infections and persistent CD4 T-cell counts of <300 cells/μL in the absence of HIV infection or another cause of lymphopenia. (D)
• SS 65. Management of ICD4L is supportive and dictated by the degree of immune compromise. (D)

Immuno-osseous dysplasias

• SS 66. The immuno-osseous dysplasias should be considered in patients with severe growth retardation, skeletal abnormalities, and T-cell lymphopenia. (C)
• SS 67. Medical management of immunoosseous syndromes should include antibiotic prophylaxis and IgG supplementation appropriate to the severity of the immune dysfunction. (C)
• SS 68. HSCT is indicated and has been successful for the correction of hematologic and immunologic defects in patients with CHH. (C)

Comel-Netherton syndrome

• SS 69. A diagnosis of Comel-Netherton syndrome (SPINK5 gene mutation) should be sought in patients with abnormal hair structure, ichthyosis, allergic disease, and increased IgE and low IgG levels. (C)

Hyper-IgE syndromes (HIES)

• SS 70. A form of HIES should be considered in patients with recurrent sinopulmonary and skin infections, chronic eczematous dermatitis, high serum IgE levels, and eosinophilia. (C)
• SS 71. The initial approach to HIES therapy should be directed toward management of complications. (C)
• SS 72. Patients with DOCK8 deficiency and poor antibody production should receive IgG replacement therapy. (C)
• SS 73. The use of IVIG or IFN-γ in patients with type 1 autosomal dominant HIES might be helpful in selected cases. (C)
• SS 74. HSCT should be considered for both forms of HIES. (C)

Hepatic veno-occlusive disease

• SS 75. Mutations in the SP110 gene should be sought in patients with hepatic veno-occlusive disease with immunodeficiency. (C)

Dyskeratosis congenita (DKC)

• SS 76. DKC should be investigated in patients with abnormal skin pigmentation, nail dystrophy, and leukoplakia of the oral mucosa. (C)

Defects of vitamin B12 and folate metabolism

• SS 77. Inborn errors of folate and vitamin B12 malabsorption should be considered in the differential diagnosis of SCID. (C)
• SS 78. Infants with severe vitamin B12 or folate deficiency should be treated aggressively with folate or cobalamin replacement as soon as the diagnosis is made. (C)

Immunodeficiency with multiple intestinal atresia (MIA)

• SS 79. Patients born with MIA should be screened for CIDs. (C)
• SS 80. HSCT should be considered for treatment of MIA-SCID. (C)