Immunity Lecture Flashcards
What is the purpose of immune system?
For survival and protection against infections
What is the innate immunity?
Natural or native
First line of defense
Always present
What are macrophages?
Evolve from monocytes formed in bone marrow
“circulating scavengers”
When monocytes differentiate and move to the tissue
Found in inflammation sites
What are natural killer cells?
“Large granular lymphcytes”
Part of innate immunity
Kills infected cells, tumor cells and possibly normal cell
What is the adaptive immunity?
Acquired or specific Silent but adapts when required Recognizes microbes and non-microbial substances "Immune response" Humoral or Cellular
What does the humoral adaptive immunity include?
B lymphocytes, antibodies, extracellular microbes
What does the cellular adaptive immunity include?
T lymphocytes, intracellular microbes
Mechanism of killing an infected cell?
Antibody secretion –> activation of macrophages –> inflammation –> stimulation of B cells –> killing of infected cell
What are dendritic cells?
Antigen presenting cells
Under epithelia –> at the site of entry of microbes
Capture microbial antigen and migrate to lymph node
What are lymphocytes?
T lymphocytes (mature in thymus)
B lymphocytes (mature in the bone marrow)
Naive concentrated in lymphoid organs
Each cell expresses receptors for a single antigen
What are T cells?
Majority in blood
Do not recognize circulating antigens
Recognize antigen peptide fragments bound to MHC
Cytotoxic, helper, and suppressor T cells
What are CD4 cells?
MHC Class II -- Helper For internalized extracellular antigens B cell- helps antibody production Macrophage- helps in phagocytosis Activates T cells and NK cells
HIV destroys what?
Helper T cells
What are CD8 cells?
For cytoplasmic antigens (viruses)
Direct killing of virus infected cells/tumor cells
Cytotoxic T cells
What does a unique antigenic profile mean?
Unique combination of HLA alleles (HLC haplotype)
Inheritance of HLA genes could be responsible for diseases and allergies
What are TH1 molecules?
Produce IFN-gamma Induce IFN-gamma and IL-2 Trigger macrophage and IgG Defend against intracellular microbes Role: immune-mediated chronic inflammation
What are TH2 molecules?
Produce IL-4/5/13 Induce IL-4 Trigger IgE, mast cells, eosinophils Defend against helminthic parasites Role: Allergies
What are TH17 molecules?
Produce IL-17 IL-22 and chemokines
Induce TGF-beta, IL-6/1/23
Trigger the recruitment of neutrophils and monocytes
Defend against extracellular bacteria and fungi
Role: immune-mediated chronic inflammation
How are B cell activated?
Naive B cells recognize antigens and under the influence of TH cells and other stiuli, the B cell are activated to proliferate and to differentiate into antibody-secreting plasma cells and some become memory cells
What are suppressor T cells?
Turns off the immune response when antigen has been eliminated
When antigens are eliminated what happens?
Effecto lymphcytes die by apoptosis
Long live memory cells remain
Subsequent exposure to antigens will lead to a faster response due to memory cells (vaccination)
