麻省理工大学课件：系统微生物学18-免疫学I(笔记)

20.106J – Systems Microbiology

Lecture 18

TA: Megan McBee

?Chapters 22 and 23

Innate immunity and inflammation

o Cells and organs

o Innate response

o Signals (chemokines, cytokines)

o Inflammation

o Adaptive immune response

Why do we have an immune system?

o Vertebrates and mammals have the most developed immune system, with both arms active

Cells of the immune system

o Differentiation starts from bone marrow cells

o Today we’ll be talking about polymorphonuclear leukocytes and

macrophages

The immune system can also be called the Lymphatic system

o Similar to the circulatory system in that there are vessels that can carry things throughout your body

o Lymph nodes

An overview of the immune response

Cell characteristics

o We’re mainly going to be talking about neutrophils

o There are PMN and Monocytes – both are phagocytic

PRRs – pathogen recognition receptors

o Toll-like receptors (TLRs) in mammals

Monocytes and Neutrophils perform phagocytosis, gobbling up the microbe and then creating a very acidic environment inside the phagolysosome to kill it o Respiratory burst

Chemokines and cytokines

o Chemokines are potent chemoattractants

CXC, CC, and C

o Cytokines are activator molecules

A lot of these are acute phase response, which can lead to septic

shock

Typically produced by leukocytes

When all these cells are attracted to the site of infection what results is inflammation

o This is visually noticeable (redness, swelling, heat, pain), so it’s been described by physicians for thousands of years, going back to ancient

Greece

o Lymph nodes, spleen, thymus, mucosal tissues

o Accumulation at the extravascular tissues

o Increased blood flow

o Increased permeability

o Emigration of leukocytes from the microcirculation and their

accumulation at the site of injury

o Leukocyte extravasation

Healing

o Resolution

o Pus formation

o Healing with fibrosis – tissue that is no longer functional

o Chronic inflammation – tissue that is no longer functional

Adaptive Immunity

o Trying to specifically target the pathogen, rather than risking damaging other cells with a generalized, nonspecific reaction

o Specificity for the antigen

o Memory – if exposed a second time, it can kick in immediately

o Tolerance – ability to discriminate self antigens from non-self antigens o Antibody-mediated immunity

o Cell-mediated immunity