Hi Zaid

That's not really a simple question to answer - you're asking for a literature review!

Briefly, DC are considered "professional" APCs and are usually thought to be the only APC capable of stimulating a response from naive, non-primed, T cells.  This is thanks to costimulatory molecules on the APC, including CD80 and CD86 (collectively called B7) and CD40.

Other professional APCs include macrophages and some specific types of epithelial cells and some spoecific B cells.

Non-professional APCs don't constitutively express MHC-II but can have it upregulated by cytokines, primarily IFNg.  Some B cells also fall into this category.

This is a much larger subject than can be answered with a short question so, rather than references, I would direct you to a textbook like Janeway's Immunobiology: http://www.ncbi.nlm.nih.gov/books/NBK10757/

Hi, Zaid!

Chris Pirson is completely right! DCs is mainly associated with priming naive T CD4 and T CD8 cells.

All kinds of APCs express costimulatory molecules but in different levels. DCs usually up-regulate these markers faster and more efficient. 

Macrophages generally present antigens to memory T cells or pre-activated cells. 

B cells act as an APC in specific situations.  First, the BCR needs to bind in antigen and uptake it, after that, B cells process and present this antigens to an activated T cell. This process happens as a stimulus to antibody production and class switch to enhance antibody antigen affinity.  It is very important to TFH priming and humoral response.

I hope it helps you

The above answers are great. Keep in mind that although these three cells are considered APCs, they cover different functions. DCs, as the most professional need less antigen for activation of their presentation capabilities. And as it is stated above, are "used" mainly for T cell activation post their migration from the tissue to the lymph tissue. DCs can also present on MHCII antigens that would be presented on MHCI in other cells (cross presentation) B cells use their APC capabilities mainly to "communicate" with already activated T cells which in turn may lead to cytokine production from both T and B cells and sometimes changes in the antibody produced by the B cells, as well as its differentiation into memory and plasma cells. The cytokines profile changes according to the type of T cell that came into contact with the B cell. I am uncertain as to where macrophages fall in their APC function. Hope this helps. 

focusing the question. The different APC cells present and process the same epitopes? all the APC present the same MHC:peptide complexes or there are differences between the different APC cell types? i mean a DC will process and present a pathogen's components in the same way a B -cell do or not? any review covering this topic?