What is the outcome when dendritic cells present antigens via class II molecules?

When dendritic cells present antigens via class II major histocompatibility complex (MHC) molecules, the primary outcome is the activation of CD4+ T helper cells, which in turn plays a significant role in stimulating B cells. The interaction occurs as follows: dendritic cells process and present antigens from extracellular sources on their class II molecules, which are recognized by T cell receptors on CD4+ T cells.

This recognition leads to the activation and proliferation of these helper T cells, which are crucial for orchestrating the immune response. Once activated, these T helper cells provide necessary signals—primarily through cytokine release—that promote the activation, differentiation, and proliferation of B cells. The B cells, stimulated by the cytokines and interactions with activated T cells, can then undergo class switching and affinity maturation, ultimately resulting in the production of antibodies specific to the presented antigen. This process is essential for generating a robust and effective adaptive immune response.

Therefore, the correct outcome of dendritic cells presenting antigens via class II molecules is the activation of B cells through the mediation of CD4+ T helper cells.