Leukocytes Flashcards
lymphoid (adaptive)
Th (helper) lymphocyte, Tr (regulatory) lymphocyte, Tc lymphocyte (or cytotoxic T cell), B lymphocyte, plasma cell
lymphoid (innate)
Natural Killer (NK) cell (null)
granulocytic myeloid cells
neutrophil, basophil, mast cell, eosinophil
antigen-presenting myeloid cells
sentinel dendritic cell, monocyte, macrophage
NOT from hematopoiesis
follicular dendritic cells
Th (helper) lymphocyte
Function: Activates inflammation, macrophages, and B cells
Characteristics: coordinates immune response
Surface expression: CD4, receptors for class II, MHC plus antigen
Responds to: antigen presented on class II MHC
Releases: variety of cytokines
TR (regulatory) lymphocyte
Function: suppresses immune response, generally and of specific lymphocytes
Characteristics: prevents allergy and autoimmune diseases
Surface expression: CD4 and CD25 when naive
Responds to: mechanism of action still mysterious
Releases: Cytokines: IL-10, TGFß
TC lymphocyte (or cytotoxic T cell)
Function: destroy altered-self cells
Characteristics: kills viral infected and malignant cells
Surface expression: CD8, receptors for class I, MHC plus antigen
Responds to: Antigen presented on class I MHC
Releases: perforin and granzymes
B lymphocyte
Function: recognize antigen, can present antigen to T cell
Characteristics: develops into plasma cell
Surface expression: membrane bound antibodies, class II MHC, complement receptors 1 and 2
Responds to: circulating antigen, TH cytokine signals
Releases: nothing
Plasma cell
Function: secretes antibodies
Characteristics: mature B cell, lives 1-2 weeks
Surface expression: no surface antibodies
Responds to: TH cytokine signals
Releases: antibodies
Natural Killer (NK) cell (null)
Function: destroy altered-self cells
Characteristics: Kills viral infected and malignant cells. Can recognize altered-self on first exposure
Surface expression: CD16-binds Fc (stem) of antibodies, MHC receptor-when activated, inhibits killing
Responds to: antibodies and down-regulated MHC I
Releases: perforin and granzymes
neutrophil
Function: phagocytosis, part of inflammatory response. Move into infected tissues
Characteristics: picks up both acidic and basic dyes, hydrolytic enzymes in granules
Surface expression: Fc and complement receptors
Responds to: chemokines
basophil
Function: important in allergy
Characteristics: picks up basic dyes e.g. methylene blue
Surface expression: Fc receptors for IgE
Responds to: chemokines
Releases: prostaglandins and leukotrienes
mast cell
Function: inflammatory response, especially to allergens
Characteristics: mature cells in skin, mucosal, digestive tract and other first defense tissues
Surface expression: Fc receptors for IgE
Eosinophil
Function: defense against parasites
Characteristics: pick up acidic dyes, e.g. eosin
Surface expression: Fc receptors for IgE
Responds to: chemokines
Releases: anti-helminth agents
sentinal dendritic cell
Function: process and present antigen to TH cells
Characteristics: covered with PM extensions, potent antigen presenters
Surface expression: Class II MHC, B7, toll-like receptors
monocyte
Function: macrophage precursors
Characteristics: circulate in blood for 8 hours, then differentiated into macrophage
macrophage
Function: phagocytosis of microorganisms and debris, present antigen after activation
Characteristics: move through tissues, differentiated from monocytes
Surface expression: Class II MHC, toll-like receptors
Responds to: Interferon from TH
follicular dendritic cells
Function: feed antibody-antigen complexes to B cells
Characteristics: found in secondary lymphoid organs
Surface expression: receptors to hold antibody-antigen complexes
