Final answer:
Antigen signaling in B cells follows common cellular mechanisms with specificity provided by the signal transduction region. B cells require dual signals from their surface antibody and T cell cytokines for full activation, indicating their role as antigen-presenting cells.
Step-by-step explanation:
Antigen signaling in B cells proceeds according to mechanisms shared among many cell types. Differences exist near the signal transduction region.
To become fully activated, a B cell must receive signals from both its surface antibody recognizing native antigen and the T cell's cytokines. The receptor on the B cell's surface, its surface immunoglobulin, must bind to the native antigen, and some of this antigen is then internalized, processed, and presented to Th2 cells on a class II MHC molecule. Simultaneously, the T cell binds using its antigen receptor, secreting cytokines that activate the B cell. This shows that B cells act as both a responder to antigenic stimulation and a professional antigen-presenting cell.