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(Dendritic cells can also present intact antigen directly to B cells. In this case, the engulfed antigen is not degraded in lysosomes but is returned to the cell surface for presentation to B cells bearing BCRs of the appropriate specificity.) </font></p>
<p><font size="2">There are at least two kinds of dendritic cell that present antigens to T cells: <br />
</font><font size="2">- DC1 and DC2 <br />
<br />
<br />
<strong>1) Th1 Cells<br />
</strong>Th1 cells are produced when DC1-type dendritic cells and pre-Th cells form an immunological synapse in which the dendritic cell <br />
- presents antigen to the T cell's receptor for antigen (TCR); <br />
- secretes interleukin 12 (IL-12). <br />
The paracrine stimulation by IL-12 activates (through JAK-STAT pathways) the Th1 cells to secrete their own lymphokines: <br />
</font><font size="2">- tumor-necrosis factor-beta (TNF-β) (also known as lymphotoxin) and <br />
- interferon-gamma (IFN-γ) <br />
These <br />
- stimulate macrophages to kill the bacteria they have engulfed; <br />
- recruit other leukocytes to the site producing inflammation.<br />
</font></p>
