aktivasi sel t

8/10/2019 Aktivasi Sel T

1/3

Aktivasi sel T

Antigen recognition by a TCR with CD4 or CD8 proteins is thefirst signal in activationof a T cell.

A T cell becomes activated only if it binds to the foreign antigenand at the same time receives asecond signal, a process known as costimulation. Of the more than 20

known costimulators, some are cytokines, such as interleukin-2. Other costimulators include pairs of

plasma membrane molecules, one on the surface of the T cell and a second on the surface of anantigen-presenting cell, that enable the two cells to adhere to one another for a period of time.

Aktivasi neutrofilFungsi: Tissue remodelingDirect harm to pathogensRegulation of proteasesVasodilation, infl ammation

Phagocytosis. Destruction of bacteria with lysozyme, defensins, and strong oxidants, such as

superoxide anion, hydrogen peroxide, and hypochlorite anion.

Fungsi eosinofil:

Induces formation of ROSVasodilation, basophil degranulation

Antiviral activityModulation of adaptive immune responses

Combat the effects of histamine in allergic reactions, phagocytize antigenantibody

complexes, and destroy certain parasitic worms.

Fungsi basofil

Liberate heparin, histamine, and serotonin in allergic reactions that intensify the overall

inflammatory response.

Fungsi sel mastmast cells release substances involved in inflammation, including heparin, histamine, and

proteases.Modulation of adaptive immune responseRegulation of inflammationVasodilation, smooth muscle activation

The principal functionsof B cellsare to make antibodies against antigens, to perform

the roleof antigen-presenting cells(APCs), and to develop into memory B cellsafter

activation by antigen interaction.

Eosinophils develop and mature in the bone marrow. They differentiate frommyeloidprecursorcells in response to the cytokinesinterleukin 3(IL-3),interleukin 5(IL-5), andgranulocytemacrophage-colony stimulating factor(GM-CSF).After maturation, eosinophils circulate in blood and migrate to inflammatory sites in tissues, or tosites ofhelminthinfection in response tochemokineslikeCCL11(eotaxin-1), CCL24 (eotaxin-2),CCL5 (RANTES), and certainleukotrieneslike leukotriene B4 (LTB4) and MCP1/4. At theseinfectious sites, eosinophils are activated by Type 2 cytokines released from a specific subsetofhelper T cells(Th2); IL-5, GM-CSF, and IL-3 are important for eosinophil activation as well asmaturation.

Aggregation of FcR1 by polyvalent antigen recognized by bound IgE activates mastcells and is the basis for anaphylaxis and other allergic diseases.FcR1 density on the

surface of mast cells is upregulated in the presence of elevated free IgE levels and in thepresence of IL-4, thus enhancing activation. In addition, mast cells are activated by C3a
http://en.wikipedia.org/wiki/Myeloidhttp://en.wikipedia.org/wiki/Myeloidhttp://en.wikipedia.org/wiki/Myeloidhttp://en.wikipedia.org/wiki/Interleukin_3http://en.wikipedia.org/wiki/Interleukin_3http://en.wikipedia.org/wiki/Interleukin_3http://en.wikipedia.org/wiki/Interleukin_5http://en.wikipedia.org/wiki/Interleukin_5http://en.wikipedia.org/wiki/Interleukin_5http://en.wikipedia.org/wiki/Granulocyte_macrophage-colony_stimulating_factorhttp://en.wikipedia.org/wiki/Granulocyte_macrophage-colony_stimulating_factorhttp://en.wikipedia.org/wiki/Granulocyte_macrophage-colony_stimulating_factorhttp://en.wikipedia.org/wiki/Helminthhttp://en.wikipedia.org/wiki/Helminthhttp://en.wikipedia.org/wiki/Helminthhttp://en.wikipedia.org/wiki/Chemokineshttp://en.wikipedia.org/wiki/Chemokineshttp://en.wikipedia.org/wiki/Chemokineshttp://en.wikipedia.org/wiki/CCL11http://en.wikipedia.org/wiki/CCL11http://en.wikipedia.org/wiki/CCL11http://en.wikipedia.org/wiki/RANTEShttp://en.wikipedia.org/wiki/RANTEShttp://en.wikipedia.org/wiki/RANTEShttp://en.wikipedia.org/wiki/Leukotrieneshttp://en.wikipedia.org/wiki/Leukotrieneshttp://en.wikipedia.org/wiki/Leukotrieneshttp://en.wikipedia.org/wiki/Helper_T_cellhttp://en.wikipedia.org/wiki/Helper_T_cellhttp://en.wikipedia.org/wiki/Helper_T_cellhttp://en.wikipedia.org/wiki/Helper_T_cellhttp://en.wikipedia.org/wiki/Leukotrieneshttp://en.wikipedia.org/wiki/RANTEShttp://en.wikipedia.org/wiki/CCL11http://en.wikipedia.org/wiki/Chemokineshttp://en.wikipedia.org/wiki/Helminthhttp://en.wikipedia.org/wiki/Granulocyte_macrophage-colony_stimulating_factorhttp://en.wikipedia.org/wiki/Granulocyte_macrophage-colony_stimulating_factorhttp://en.wikipedia.org/wiki/Interleukin_5http://en.wikipedia.org/wiki/Interleukin_3http://en.wikipedia.org/wiki/Myeloid


2/3


3/3

yang mengaktivasi makrofag, tetapi makrofag juga diaktivkan oleh kontak denganlimfosit T melalui CD 40.

Aktivasi makrofag diakibatkan adanya peningkatan transkripsi gen-gen dimana sitokin

aktivator makrofag yang poten adalah IFN-gamma. IFN-gamma bukanlah satu-satunya

sitokin yang mengaktivasi makrofag, tetapi makrofag juga diaktifkan oleh kontak denganlimfosit T melalui CD 40.

B cell activation requires both antigen engagement by the B-cell receptor (BCR) and direct contact

with an activated CD4_ TH cell. Both events are facilitated by the anatomy of the lymph node. Like T

cells, B cells circulate through the blood and lymph and visit the lymph nodes on a daily basis,

entering via the HEV. They respond to specific signals and chemokines that draw them not to the

paracortex but to the lymph node follicle. Although they may initially take advantage of the FRCC for

guidance, they ultimately depend upon follicular dendritic cells (FDCs) for guidance (Figure 2-9c).

FDCs are centrally important in maintaining follicular and germinal center structure and presenting

antigen to differentiating B cells.

B cells differ from T cells in that their receptors can recognize free antigen. A B cell will typically meet

its antigen in the follicle. If its BCR binds to antigen, the B cell becomes partially activated and engulfs

and processes that antigen. As mentioned above, B cells, in fact, are specialized antigen-presenting

cells that present processed peptide- MHC complexes on their surface to CD4_ TH cells. Recent

data show that B cells that have successfully engaged and processed antigen change their migration

patterns and move to the T-cell-rich paracortex, where they increase their chances of encountering an

activated CD4_ TH cell that will recognize the MHC-antigen complex they present.

When they successfully engage this TH cell, they maintain contact for a number of hours, becoming

fully activated and receiving signals that induce B cell proliferation (see Chapter 14).

Some activated B cells diff erentiate directly into an antibody- producing cell (plasma cell) but others

re-enter the follicle to establish a germinal center. A follicle that develops a germinal center is

sometimes referred to as a secondaryfollicle; a follicle without a germinal center is sometimes

referred to as a primary follicle.

aktivasi sel t

Documents