What is the Difference Between Professional and Non-professional Antigen Presenting Cells?

The main difference between professional and non-professional antigen-presenting cells (APCs) lies in their ability to present antigens to T cells and their expression of MHC class II molecules and co-stimulatory molecules. Here are the key differences:

1. Origin: Professional APCs are of hematopoietic origin, while non-professional APCs are not bone marrow-derived.
2. MHC Class II Expression: Professional APCs constitutively express MHC class II molecules, while non-professional APCs do not.
3. Co-stimulatory Molecules: Professional APCs express potent co-stimulatory molecules, which are absent in non-professional APCs.
4. Immune Response: Professional APCs can induce both primary and secondary immune responses, while non-professional APCs may only initiate primary and secondary immune responses after induction of MHC class I by IFN-gamma.
5. Antigen Presentation: Professional APCs can present antigens to both helper and cytotoxic T cells, while non-professional APCs can only present antigens to helper T cells.

Examples of professional APCs include dendritic cells, macrophages, and B cells, while non-professional APCs include fibroblasts, endothelial cells, and hepatocytes. Non-professional APCs can be further classified into semiprofessional, nonprofessional, or nonantigen-presenting cells based on their ability to present antigens to and activate various types of T cells.

Comparative Table: Professional vs Non-professional Antigen Presenting Cells

Here is a table comparing the differences between professional and non-professional antigen-presenting cells:

Both professional and non-professional antigen-presenting cells play a vital role in the adaptive immune system of the body. However, professional antigen-presenting cells, such as dendritic cells, macrophages, and B cells, are part of the hematopoietic lineage and express both MHC class I and class II molecules. In contrast, non-professional antigen-presenting cells, like fibroblasts, only express MHC class I molecules.