Читать книгу Immunology - Richard Coico - Страница 56

1 The common lymphoid progenitor cell derived from the hematopoietic stem cell in the bone marrow gives rise to each of the lymphocyte populations.

2 The organs in which lymphocyte maturation, differentiation, and proliferation take place are divided into two categories: primary and secondary organs.

3 Primary lymphoid organs are sites where gene rearrangements occur to generate functional antigen‐specific BCRs and TCRs expressed by B and T cells, respectively.

4 Mature B cells differentiate to fully mature cells within the bone marrow.

5 T cells begin to develop within the bone marrow and undergo maturation to mature populations in the thymus.

6 Macrophages are functionally polarized into M1 or M2 macrophages. Such polarization is regulated by the cytokines and other molecules and conditions present in the local environment.

7 The secondary lymphoid organs include the spleen, lymph nodes, Peyer’s patches in the small intestine, the MALT, GALT, and BALT.

8 Secondary lymphoid tissues are highly efficient in trapping and concentrating foreign substances and are the main sites of production of antibodies and the induction of antigen‐specific T lymphocytes.

9 The lymphatic system is a network of lymphatic vessels that contain a clear fluid called lymph. All interstitial spaces are drained by the lymphatic system, ensuring that foreign antigens will be swept away and deposited within a draining lymph node where antigen‐presenting cells and antigen‐specific T and B cells can initiate an immune response.

10 T cell antigen engagement in secondary lymphoid tissues shapes the repertoire of antigen‐specific T cells, driving them to differentiate towards specific functional subsets including TH1, TH2, TH17, TReg, and TFH cells. Each subset displays characteristic cytokine and transcription factors.

11 Blood lymphocytes enter the lymph nodes through postcapillary venules and leave the lymph nodes through efferent lymphatic vessels, which eventually converge in the thoracic duct. The duct empties into the vena cava, the vessel that returns the blood to the heart, thus providing for the continual recirculation of lymphocytes.