AH 3121 Chapter Notes - Chapter 7: Mhc Class Ii, Endocytosis, Immunoglobulin Heavy Chain
Document Summary
The complement system: functions as an effector mechanism of host defenses, second signal for b cell activation, a collection of plasma proteins. Activated by antibodies attached to microbes: microbe becomes coated with c3d, a breakdown product of c3, the most abundant complement protein. C3d a fragment of c3 that ca coat microbes and allow activation of b cells. Co-receptor protein functions: cr2 binds to complement components (c3d) on the pathogen. C3d plays an essential role: cd19 acts as signaling chain of the receptor (b cell, cd81 unknown function, but is the surface receptor for hepatitis c virus (hcv) The final outcome of all of this is the translation of proteins that control b cell proliferation and differentiation. Clonal expansion, b cell differentiation, & t cells/lymphocytes in humoral. After the above processes, clonal expansion and differentiation of b cells can now take place: the diagram to the right shows an example of t-dependent b cell activation.
