Help with Immunology

[FoxintheBox]

For an upcoming test I will be required to write an essay that will ask to describe the entire immune response, only in general however. What I have so far is as follows:

The first defense against pathogens is the skin and mucosa. If a pathogen is able to get past these barriers it will enter the blood and be consumed by a macrophage; if the pathogen is a virus it will enter into a cell and eventually be presented on that cell as an epitope+MHCI protein. Otherwise the macrophage will then degrade the pathogen into epitopes and present them on its surface bound to MHCII proteins.

The Epitope+MHCI or MHCII will then stimulate Thelper cells. Thelper cells then stimulate both Tcytotoxic and Naive Bcells. T cytotoxic cells move to the site of inflammation by chemotaxis and either secrete perforin or differentiate into T suppresor cells. Stimulated Bcells either differentiate into plasma cells or memory b cells. Plasma cells secrete antibodies, memory b cells move to and wait at the site where the pathogen was detected.

Once Antibodies are produced they will bind to and neutralize/opsonize/agglutinate the pathogen. Antiboy binding also triggers the complement system that forms a membrane attack complex to lyse nearby cells.

Is that all accurate? Anything I forgot?

[mith]

MHC 1 does not get presented to helper cells.

[sdekivit]

helper T cells do not directly activate cytotoxic T cells; these can be activated by the antigen presenting cells directly after interacting with the MHC-I:antigen complex and costimulatory molecules.

However, helper T cells activate APCs more then the recognition of the potential harmful antigen and so the APC expresses even more costimulatory molecules (and thus the CD8+ T cell is indirectly activated by the CD4+ T cell)