immunology
Posted: Thu Feb 23, 2006 4:48 pm
Hi Experts,
I have started conducting my research on curcumin. Linh had recommended looking through the Janeway immunology textbook for background information to help me. Through the course of reading, I encountered a passage that was difficult for me to understand. I have copied it here.
8-3. Lymphocyte migration, activation, and effector function depend on cell-cell interactions mediated by cell-adhesion molecules.
The migration of naive T cells through the lymph nodes, and their initial interactions with antigen-presenting cells, depend on cells binding to each other through interactions that are not antigen-specific. Similar interactions eventually guide the effector T cells into the peripheral tissues and play an important part in their interaction with target cells. Binding of T cells to other cells is controlled by an array of adhesion molecules on the surface of the T lymphocyte that recognize a complementary array of adhesion molecules on the surface of the interacting cell. The main classes of adhesion molecule involved in lymphocyte interactions are the selectins, the integrins, members of the immunoglobulin superfamily, and some mucinlike molecules. We have already encountered members of the first three classes in the recruitment of neutrophils and monocytes to sites of infection during an innate immune response (see Section 2-22). Most adhesion molecules play fairly broad roles in the generation of immune responses. Many that are involved in lymphocyte migration and the interactions of armed effector T cells with their targets are also involved in interactions between other leukocytes. Adhesion molecules are important in getting lymphocytes together in adaptive immune responses that involve T-cell-B-cell interactions, and we will describe these in Chapter 10, where we present an integrated view of the immune response.
The selectins (Fig. 8.5) are particularly important for leukocyte homing to particular tissues, and can be expressed either on leukocytes (L-selectin, CD62L) or on vascular endothelium (P-selectin, CD62P, and E-selectin, CD62E). L-Selectin is expressed on naive T cells and guides their exit from the blood into peripheral lymphoid tissues. P-Selectin and E-selectin are expressed on the vascular endothelium at sites of infection and serve to recruit effector cells into the tissues at these sites (see Sections 2-21 and 2-22). Selectins are cell-surface molecules with a common core structure, distinguished from each other by the presence of different lectinlike domains in their extracellular portion (see Fig. 2.34). The lectin domains bind to particular sugar groups, and each selectin binds to a cell-surface carbohydrate. L-Selectin binds to the carbohydrate moiety, sulfated sialyl-Lewisx, of mucinlike molecules called vascular addressins, which are expressed on the surface of vascular endothelial cells. Two of these addressins, CD34 and GlyCAM-1, are expressed as sulfated sialyl-Lewisx molecules on high endothelial venules in lymph nodes. A third, MAdCAM-1, is expressed on endothelium in mucosa, and guides lymphocyte entry into mucosal lymphoid tissue such as that of the gut.
From what I understand, the migration of naive T cells through the lymph nodes depend on the adhesion molecules. What I don't understand is the lectinlike domains and the vascular addressins.
I apologize that it is such a long passage that I cut out of the textbook. I received this information from the Janeway immunobiology textbook edition 5.
Thank you,
Sareena
I have started conducting my research on curcumin. Linh had recommended looking through the Janeway immunology textbook for background information to help me. Through the course of reading, I encountered a passage that was difficult for me to understand. I have copied it here.
8-3. Lymphocyte migration, activation, and effector function depend on cell-cell interactions mediated by cell-adhesion molecules.
The migration of naive T cells through the lymph nodes, and their initial interactions with antigen-presenting cells, depend on cells binding to each other through interactions that are not antigen-specific. Similar interactions eventually guide the effector T cells into the peripheral tissues and play an important part in their interaction with target cells. Binding of T cells to other cells is controlled by an array of adhesion molecules on the surface of the T lymphocyte that recognize a complementary array of adhesion molecules on the surface of the interacting cell. The main classes of adhesion molecule involved in lymphocyte interactions are the selectins, the integrins, members of the immunoglobulin superfamily, and some mucinlike molecules. We have already encountered members of the first three classes in the recruitment of neutrophils and monocytes to sites of infection during an innate immune response (see Section 2-22). Most adhesion molecules play fairly broad roles in the generation of immune responses. Many that are involved in lymphocyte migration and the interactions of armed effector T cells with their targets are also involved in interactions between other leukocytes. Adhesion molecules are important in getting lymphocytes together in adaptive immune responses that involve T-cell-B-cell interactions, and we will describe these in Chapter 10, where we present an integrated view of the immune response.
The selectins (Fig. 8.5) are particularly important for leukocyte homing to particular tissues, and can be expressed either on leukocytes (L-selectin, CD62L) or on vascular endothelium (P-selectin, CD62P, and E-selectin, CD62E). L-Selectin is expressed on naive T cells and guides their exit from the blood into peripheral lymphoid tissues. P-Selectin and E-selectin are expressed on the vascular endothelium at sites of infection and serve to recruit effector cells into the tissues at these sites (see Sections 2-21 and 2-22). Selectins are cell-surface molecules with a common core structure, distinguished from each other by the presence of different lectinlike domains in their extracellular portion (see Fig. 2.34). The lectin domains bind to particular sugar groups, and each selectin binds to a cell-surface carbohydrate. L-Selectin binds to the carbohydrate moiety, sulfated sialyl-Lewisx, of mucinlike molecules called vascular addressins, which are expressed on the surface of vascular endothelial cells. Two of these addressins, CD34 and GlyCAM-1, are expressed as sulfated sialyl-Lewisx molecules on high endothelial venules in lymph nodes. A third, MAdCAM-1, is expressed on endothelium in mucosa, and guides lymphocyte entry into mucosal lymphoid tissue such as that of the gut.
From what I understand, the migration of naive T cells through the lymph nodes depend on the adhesion molecules. What I don't understand is the lectinlike domains and the vascular addressins.
I apologize that it is such a long passage that I cut out of the textbook. I received this information from the Janeway immunobiology textbook edition 5.
Thank you,
Sareena