Updated: 4/5/2021

Cells of the Immune System

0%
Topic
Review Topic
0
0
N/A
N/A
Questions
5
0
0
0%
0%
Evidence
2
0
0
0%
0%
Videos / Pods
1
Topic
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
  • IL2 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
  • Involved in allergic responses 
  • 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

Please rate topic.

Average 5.0 of 9 Ratings

Questions (5)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Evidence (2)
VIDEOS & PODCASTS (2)
EXPERT COMMENTS (17)
Private Note