What happen when inactive T cell encounters an antigen?

Unless they encounter their antigen, both types of cells soon leave the lymph node via lymphatic vessels. If they encounter their antigen, however, they remain in the node, proliferate, and differentiate into either effector cells or memory cells.

What is the immune response to Streptococcus pneumoniae?

Streptococcus pneumoniae has been shown to activate phagocytic cells and then be destroyed through different mechanisms involving TLRs, subsequently inducing B cells to produce cytokines including TNF-α, IL-6, and pro-IL-1β [30-35].

What organ is responsible for eliminating C3b tagged erythrocytes for Opsonization?

Opsonization and pathogen clearance Additionally, C3b molecules can attach to the Fc regions of antigen-bound antibodies leading to phagocytosis or movement to the liver, where the C3b-tagged immune complex is then destroyed.

How do T cells become activated in response to antigen stimulation?

Helper T cells become activated by interacting with antigen-presenting cells, such as macrophages. Antigen-presenting cells ingest a microbe, partially degrade it, and export fragments of the microbe—i.e., antigens—to the cell surface, where they are presented in association with class II MHC molecules.

How does Streptococcus pneumoniae damage cells?

pneumoniae induces toxic DNA double-strand breaks (DSBs) in human alveolar epithelial cells, as indicated by ataxia telangiectasia mutated kinase (ATM)-dependent phosphorylation of histone H2AX and colocalization with p53-binding protein (53BP1).

How does Streptococcus pneumoniae evade the immune system?

In order to evade the anti-bacterial effects of complement, pneumococci have developed many virulence factors that impair complement activity, thus contributing to bacterial evasion from the immune system (Jarva et al., 2003).

What is important about the shape of the antigen-binding site?

The biconcave shape of the cell allows oxygen exchange at a constant rate over the largest possible area.

What are the functions of C3b?

The human C3b receptor (CR1) is a polymorphic glycoprotein which functions regulating the complement system by inhibiting the activation of C3 and C5, through its effect on their convertases, and serving as cofactor for factor I in mediating the degradation of C3b to its inactive fragment C3bi and further to C3d-g.

What causes the formation of the C3 convertase enzyme?

Cleavage of complement C3 by a free floating convertase, thrombin, plasmin or even a bacterial enzyme leads to formation of C3a and C3b fragments. After cleavage and binding to cell surface, the C3b fragment is ready to bind a plasma protein called Factor B.