Normal Values of Immunology Parameters

Immunology is the branch of biomedical science that studies the structure, function, and regulation of the immune system, including innate immunity, adaptive immunity, humoral immunity, cellular immunity, complement pathways, cytokine networks, immunoglobulins, leukocyte subsets, and immunogenetics. Immunological reference values provide standardized benchmarks for evaluating immune competence, immune dysregulation, autoimmune diseases, immunodeficiency disorders, transplant monitoring, allergy testing, infectious diseases, and immunotherapeutic responses. Modern immunology laboratories employ flow cytometry, nephelometry, turbidimetry, ELISA, chemiluminescence immunoassays, multiplex cytokine assays, immunofluorescence, immunoblotting, and molecular immunodiagnostic techniques to quantify immune parameters.

Immunoglobulin Parameters

Immunoglobulins (antibodies) are glycoproteins produced by plasma cells and constitute the principal mediators of humoral immunity.

Serum Immunoglobulin G (IgG)

Parameter	Reference Range
Adult	700–1600 mg/dL
SI Units	7–16 g/L

IgG Subclasses

Subclass	Reference Range
IgG1	341–894 mg/dL
IgG2	171–632 mg/dL
IgG3	18–106 mg/dL
IgG4	2.4–121 mg/dL

Serum Immunoglobulin A (IgA)

Parameter	Reference Range
Adult	70–400 mg/dL
SI Units	0.7–4.0 g/L

Serum Immunoglobulin M (IgM)

Parameter	Reference Range
Adult	40–230 mg/dL
SI Units	0.4–2.3 g/L

Serum Immunoglobulin E (IgE)

Parameter	Reference Range
Adult	<100 IU/mL
SI Units	<240 ng/mL

Serum Immunoglobulin D (IgD)

Parameter	Reference Range
Adult	<15 mg/dL

Complement System Parameters

The complement cascade comprises more than 30 plasma proteins involved in innate immunity, opsonization, inflammation, and membrane attack complex formation.

Total Complement Activity

Parameter	Reference Range
CH50	30–75 U/mL
AH50	70–130% Activity

Individual Complement Components

Component	Reference Range
C3	90–180 mg/dL
C4	10–40 mg/dL
C1q	70–180 mg/L
C2	1.6–4.0 mg/L
Factor B	90–320 μg/mL
Properdin	10–33 μg/mL

Lymphocyte Subset Analysis (Flow Cytometry)

Total Lymphocyte Count

Parameter	Reference Range
Absolute Lymphocyte Count	1000–4000 cells/μL

T-Lymphocyte Parameters

CD3+ T Cells

Parameter	Reference Range
Percentage	60–85%
Absolute Count	800–2500 cells/μL

CD4+ Helper T Cells

Parameter	Reference Range
Percentage	30–60%
Absolute Count	500–1600 cells/μL

CD8+ Cytotoxic T Cells

Parameter	Reference Range
Percentage	15–40%
Absolute Count	200–900 cells/μL

CD4/CD8 Ratio

Parameter	Reference Range
CD4/CD8 Ratio	1.0–3.5

B-Lymphocyte Parameters

CD19+ B Cells

Parameter	Reference Range
Percentage	5–20%
Absolute Count	100–500 cells/μL

CD20+ B Cells

Parameter	Reference Range
Percentage	5–20%

Natural Killer (NK) Cells

CD16+/CD56+ Cells

Parameter	Reference Range
Percentage	5–30%
Absolute Count	90–600 cells/μL

Cytokine Reference Values

Cytokines are soluble signaling proteins regulating immune responses.

Pro-inflammatory Cytokines

Cytokine	Reference Range
IL-1β	<5 pg/mL
IL-6	<7 pg/mL
TNF-α	<8 pg/mL
IL-17A	<20 pg/mL

Anti-inflammatory Cytokines

Cytokine	Reference Range
IL-10	<10 pg/mL
TGF-β1	1–10 ng/mL

T-cell Regulatory Cytokines

Cytokine	Reference Range
IL-2	<15 pg/mL
IL-4	<5 pg/mL
IL-5	<10 pg/mL
IFN-γ	<15 pg/mL

Acute Phase Reactants

C-Reactive Protein (CRP)

Parameter	Reference Range
CRP	<5 mg/L
High-Sensitivity CRP	<1 mg/L

Serum Amyloid A

Parameter	Reference Range
SAA	<10 mg/L

Autoimmune Screening Parameters

Antinuclear Antibody (ANA)

Parameter	Reference Range
ANA	Negative
Titer	<1:80

Rheumatoid Factor (RF)

Parameter	Reference Range
RF	<14 IU/mL

Anti-Cyclic Citrullinated Peptide (Anti-CCP)

Parameter	Reference Range
Anti-CCP	<20 U/mL

Anti-dsDNA Antibody

Parameter	Reference Range
Anti-dsDNA	<30 IU/mL

Extractable Nuclear Antigen (ENA) Profile

Antibody	Reference Result
Anti-Sm	Negative
Anti-RNP	Negative
Anti-SSA/Ro	Negative
Anti-SSB/La	Negative
Anti-Scl-70	Negative
Anti-Jo-1	Negative

Allergy and Hypersensitivity Parameters

Total IgE

Parameter	Reference Range
Adult	<100 IU/mL

Eosinophil Cationic Protein (ECP)

Parameter	Reference Range
ECP	<24 ng/mL

Serum Tryptase

Parameter	Reference Range
Baseline Tryptase	<11.4 ng/mL

Transplant Immunology Parameters

Panel Reactive Antibody (PRA)

Parameter	Reference Range
PRA Class I	<10%
PRA Class II	<10%

Donor-Specific Antibody (DSA)

Parameter	Reference Result
DSA	Negative

Major Histocompatibility Complex (MHC)

HLA Expression

Parameter	Reference Value
HLA Class I Expression	Present on All Nucleated Cells
HLA Class II Expression	APCs Only

Immunodeficiency Screening Parameters

Neutrophil Oxidative Burst

Parameter	Reference Range
DHR Assay Positive Cells	>95%

Lymphocyte Proliferation Assays

Parameter	Reference Range
Mitogen Response	Normal Stimulation Index >20

Advanced Flow Cytometric Immunophenotyping

Marker	Normal Range
CD45+ Leukocytes	>95%
CD34+ Stem Cells (Peripheral Blood)	<0.1%
Regulatory T Cells (CD4+CD25+FoxP3+)	5–10% of CD4 Cells
Memory B Cells (CD27+)	10–35% of B Cells
Naive T Cells	30–70% of T Cells

Mucosal Immunology Parameters

Secretory Immunoglobulin A (sIgA)

Parameter	Reference Range
Salivary sIgA	70–400 μg/mL

Fecal Calprotectin

Parameter	Reference Range
Fecal Calprotectin	<50 μg/g Stool

Immunogenetics Parameters

Kappa/Lambda Free Light Chain Ratio

Parameter	Reference Range
κ/λ Ratio	0.26–1.65

Serum Free Light Chains

Parameter	Reference Range
Kappa	3.3–19.4 mg/L
Lambda	5.7–26.3 mg/L

References

• Roitt's Essential Immunology.
• Kuby Immunology.
• Janeway's Immunobiology.
• Clinical Immunology Principles and Practice.
• Henry's Clinical Diagnosis and Management by Laboratory Methods.
• Clinical and Laboratory Standards Institute.
• World Health Organization.
• International Union of Immunological Societies.
• American Association of Immunologists.
• European Federation of Immunological Societies.