Skin and mucous membranes, blood-brain, blood-fetal barrier

Local secretion of inhibitory and bactericidal substances in the skin and mucous membranes

Non-specific effector cells and effector molecules

Hematopoietic organs: the birthplace of various blood cells and immune cells

The place where B cells develop, differentiate, and mature

1. The thymus is the place where T cells differentiate and mature.

2. Secrete thymus hormones and cytokines

3. Immune regulatory function

4. Establish self-tolerance and maintain immune homeostasis

Filtration: a place where T and B lymphocytes settle and increase their value

generate specific immune response

Filtration function: Lymphocyte settlement, value-added place

generate specific immune response

Synthetic secretory effects: such as complement, cytokines

Binding of TCR to antigen peptide_MHC complex

APC uptake

APC processes, processes, and presents antigens

Th cell activation requires dual signal stimulation

1. Cytotoxic effect mediated by CD8 CTL

2. CD4 Th1 cells mediate DTH

3. CD4 Th2 cells assist B cells in producing antibodies

BCR directly recognizes the B cell epitope of the antigen and transmits specific recognition signals (activation signal 1)) by Iga and Igβ.

The co-stimulatory molecule interaction between activated Th2 and B cells (CD40L/CD40) provides activation signals to B cells 2)

This response is not restricted by MHC, does not require APC and Th assistance, does not respond again, and occurs early.

A specific antigen stimulates the body for the first time, with low output and short maintenance time. The antibodies produced are mainly IgM type, with low affinity and low specificity.

After the initial response, the same antigen is stimulated again. The antibody yield is high and the maintenance time is long. The antibodies produced are mainly IgG type, with high affinity and high specificity.

TCR_CD3 complex

CD4 and CD8 molecules

Classification according to the function of T cells

BCR complex

composition

effect

NK cell function

NK cells are lymphocytes

APC can process, uptake, process antigen and present antigen information to T cells

Binding to membrane proteins between lymphocytes is the initiating factor for lymphocyte activation, proliferation, and effects.

1. Dendritic cells

2. Mononuclear phagocyte system (MPS))

3, B cells

conditioning effect

Antigen-dependent cell-mediated cytotoxicity

Mediates type I hypersensitivity reactions

IgG crosses the placenta