Updated: 2/12/2018

Cells of the Immune System

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Overview
 

This illustration highlights the basic development of various blood cells from hematopoietic stem cells.

 
Introduction
  • The immune system involves cells from two major lineages including
    • lymphoid cells derived from a lymphoid progenitor such as
      • natural killer (NK) cells
      • T-lymphocytes
      • B-lymphocytes
    • myeloid cells derived from a myeloid progenitor such as
      • mast cells
      • basophils
      • neutrophils
      • eosinophils
      • monocytes
      • macrophages
  • These cells carry out many of the major roles of the immune system including
    • phagocytosis of invading microbes
    • secretion of the protein components of humoral immunity such as
      • antibodies
    • production of toxic substances such as
      • reactive oxygen species
    • direct cytotoxic signals through receptor based interactions
Lymphoid Cells
  • Lymphoid cells can broadly be divided into four classes including
    • NK cells that kill cells without major histocompatability complexes (MHC)
    • T-cells that can be further subdivided into
      • killer T-cells that are directly cytotoxic
      • helper T-cells that enable other immune functions
      • regulatory T-cells that maintain immune tolerance
    • B-cells that mediate humoral immunity
Lymphoid Cell Types
Feature NK Cells B Cells Killer T
Helper T
Regulatory T
Function
  • Kill cells lacking MHC
  • Secrete antibodies
  • Kill infected cells
  • Enable other immune cells
  • Suppress immunity
Surface proteins
  • CD56
  • MHC receptor
  • CD19, 20, and 21
  • CD40
  • CD2
  • CD3
  • CD8
  • CD2
  • CD3
  • CD4
  • CD3
  • CD4
  • CD25
  • FOXP3
    • deficiency results in IPEX (Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked) syndrome
Secreted proteins
  • Perforin
  • Granzymes
  • Antibodies
  • Toxic compounds
  • Diverse cytokines
  • IL10
  • TGF-B
  • Helper T-cells (CD4+ cells) can be further subdivided into classes based on function
Helper T-Cell Subtypes
Feature Th1 Th2
Th17
Function
  • Promote cell based immunity
  • Activate macrophages and cytotoxic T-cells
  • Promotes humoral immunity
  • Recruits eosinophils as part of parasite defence
  • Activate neutrophils
Differentiation
  • IFN-γ
  • IL-12
  • IL-2
  • IL-4
  • IL-6
  • TGF-β
Associations
  • Granuloma formation
  • Tuberculous leprosy
  • Lepromatous leprosy
  • IgE production by B cells
  • Chronic inflammatory conditions
Secreted Factors
  • IFN-γ
  • IL-2 
  • IL-4
  • IL-5
  • IL-13
  • IL-17
  • IL-21
 
Myeloid cells
  • Myeloid cells perform a large variety of innate immune functions including
    • phagocytosis of invading antigens
    • secretion of cytokines and immunoactive proteins
    • clearance of cellular debris
    • presentation of antigens to adaptive immune system
    • alteration of vascular physiology
  • Different innate immune cells are specialized for different functions
Myeloid Cell Types
Cell Type Functions and Features
Monocytes
  • Phagocytosis of invading pathogens
  • Differentiates into macrophages
  • Express receptors for the antibody Fc and the complement protein C3b
Macrophages
  • Phagocytosis of pathogens as well as cellular debris
  • Secretion of cytokines
  • Stimulation of the healing response
Dendritic cells
  • Capture of antigens from pathogens
  • Presentation of antigens to adaptive immune cells
  • Called Langerhans cells in skin and mucosa
Neutrophils
  • Secretion of cytokines and signaling molecules
  • Phagocytosis of pathogens
  • Generation of reactive oxygen species
Eosinophils
  • Production of major basic protein
  • Anti-parasitic defence
Basophils
  • Allergic response
Mast cells
  • Production and release of histamine
  • Allergic repsonse
 

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Questions (4)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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