Cells of the Immune System
Granulocytes
• Neutrophils: most numerous and
important
• Basophils: allergic response
• Eosinophils: allergic response
Mast Cells
• Non-phagocytic cells
• Involved in allergic reaction (histamine
release)
• Cause vasodilation and increase vascular
permeability (inflammation)
Macrophages
• Engulf bacteria, cells and products targeted by the
innate and adaptive response elements:
– PAMPS
– Complement
– Antibody
• Present to TH cells for activation
• Long lived and capable of producing more
lysosomes
Dendritic Cells
• Antigen presenting cells (APC):
– Phagocytize bacteria
– Present parts of bacteria and their products on
their surface receptors (MHC-II and MHC-I)
– Activates T cells for adaptive immune response
Lymphoid Cell Lines
• T cells and B cells with specific antigen
receptors
• Natural killer cells: lymphoid cell line but
NOT part of the adaptive immune system
– Large granular lymphocytes
– Kill cells that are abnormal such as viralinfected and tumors
Lymphoid Tissues
• Primary lymphoid organs (central):
– Thymus
– Bone marrow
• Secondary lymphoid organs (peripheral)
–
–
–
–
–
Lymph nodes
Spleen
Mucosal lymphoid tissues: GALT
Tonsils, adenoids
Appendix
T-cells
• T-cell receptor (TCR) member of the
immunoglobulin super family
– Helper T cell (TH): activate macrophages and B
cells. Also called CD4 cells
– Cytotoxic T cell (TC): kill intracellularly
infected cells. Also called CD8 cells
B cells
• B-cell receptor (BCR) binds the antigen
– Presents to TH cells for activation
– cell proliferation and differentiation
– Plasma cells and some memory cells
• Antibodies produced have the same
specificity as the BCR (membrane Ig)
Cellular Interaction
• Macrophages bind pathogens and engulf
them (cytokines are produced)
– Neutrophils are recruited in to engulf bacteria
• Dendritic cells engulf and begin to travel to
nearest lymphatic tissue
– Maturation includes presenting antigen
– Presenting co-stimulatory molecules
Adaptive Immune Response
•
•
•
•
Mature dendritic cells activate T cells
TH cells will activate B cells
B cells produce antibodies as plasma cells
TC cells travel to the site of infection and
kill infected cells
Immune System Cells
• Myeloid cells have receptors that bind cells
based on conserved patterns
• Lymphocytes have specific unique
receptors that can recognize pathogens and
their products
https://www.bing.com/images/search?q=initiation+of+adaptive+immune+response&view=detailv2&id=93EBADA5CA653A8183F10A4669E009A7DDEA3A55&selectedindex=
7&ccid=MUHk9tUZ&simid=608019722209264909&thid=OIP.M3141e4f6d5198ff8c82d91e2e8cfad06o0&mode=overlay&first=1