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

The main difference between professional and non-professional antigen-presenting cells is that professional antigen-presenting cells have a hematopoietic origin, whereas non-professional antigen-presenting cells have a non-hematopoietic origin.

Professional and non-professional antigen-presenting cells are two types of cells that can initiate primary and secondary immune responses. Both express MHC molecules.

Key Areas Covered

1. What are Professional Antigen Presenting Cells
     – Definition, Features, Importance
2. What are Non-professional Antigen Presenting Cells
     – Definition, Features, Importance
3. Similarities – Professional and Non-professional Antigen Presenting Cells
     – Outline of Common Features
4. Difference Between Professional and Non-professional Antigen Presenting Cells
     – Comparison of Key Differences

Key Terms

Non-professional Antigen Presenting Cells, Professional Antigen Presenting Cells

What are Professional Antigen Presenting Cells

Professional antigen-presenting cells are the cells of the hematopoietic lineage, constitutively expressing MHC class I and II molecules. They are dendritic cells, macrophages, and B cells. T cells must be activated to divide and perform their function. Professional antigen-presenting cells present antigens to T cells to recognize by their T cell receptors. Usually, these professional antigen-presenting cells are dendritic cells. There are two types of T cells: helper T cells and cytotoxic T cells. Helper T cells recognize antigens when presented with MHC class II molecules, while cytotoxic T cells recognize antigens when presented with MHC class I molecules.

Figure 1: Antigen Presentation

Furthermore, professional antigen-presenting cells efficiently internalize antigens by phagocytosis in macrophages and dendritic cells or receptor-mediated endocytosis in B cells. Then, they process antigens to peptide fragments and display them bound to MHC class II molecules. T cells can recognize these antigens leading to the activation of T cells.

What are Non-professional Antigen Presenting Cells

Non-professional antigen-presenting cells are the type of cells that express only MHC class I molecules. Their origin is non-hematopoietic. All nucleated cells are non-professional antigen-presenting cells. They display endogenous antigens on the cell membrane. In contrast, exogenous antigens are displayed by professional antigen-presenting cells. However, non-professional antigen-presenting cells do not express MHC class II molecules. Apart from that, there are three types of non-professional antigen-presenting cells: semiprofessional-, nonprofessional-, or nonantigen-presenting cells. They present antigens to naive T cells, activated T cells, or no T Cells, respectively, and activate them.

Figure 2: Hematopoiesis

There is also another type of antigen-presenting cells called atypical antigen-presenting cells. They include neutrophils, basophils, and eosinophils. They can be induced to express MHC class II molecules.

Similarities Between Professional and Non-professional Antigen Presenting Cells

• Professional and non-professional antigen-presenting cells are two types of antigen-presenting cells that occur in the body.
• Both types of cells can generate primary and secondary immune responses.
• They express MHC molecules.

Difference Between Professional and Non-professional Antigen Presenting Cells

Definition

Professional antigen-presenting cells refer to the cells with the ability to capture and process foreign antigens and to deliver the three signals for T cell activation, while non-professional antigen-presenting cells refer to all nucleated cells in the body that express MHC class I molecules.

Lineage

Professional antigen-presenting cells have a hematopoietic origin, while non-professional antigen-presenting cells have a non-hematopoietic origin.

MHC Molecules

Moreover, professional antigen-presenting cells express both MHC class I and MHC class II molecules, while non-professional antigen-presenting cells do not express MHC class II molecules.

Examples

Professional antigen-presenting cells include dendritic cells, macrophages, and B cells, while all nucleated cells in the body are non-professional antigen-presenting cells.  

Conclusion

In brief, professional and non-professional antigen-presenting cells are two types of cells that present antigens to T cells. They can generate both primary and secondary immune responses. Both express MHC molecules. However, professional antigen-presenting cells belong to the hematopoietic lineage. They express both MHC class I and class II molecules. Examples of professional antigen-presenting cells are dendritic cells, macrophages, and B cells. In comparison, non-professional antigen-presenting cells do not belong to the hematopoietic lineage. All nucleated cells in the body are non-professional antigen-presenting cells. They do not express MHC class II molecules. Therefore, the main difference between professional and non-professional antigen-presenting cells is their potential to present antigens to T cells.

References:

1. Sundstrom JB, Ansari AA. Comparative study of the role of professional versus semiprofessional or nonprofessional antigen presenting cells in the rejection of vascularized organ allografts. Transpl Immunol. 1995 Dec;3(4):273-89. doi: 10.1016/0966-3274(95)80013-1. PMID: 8665146.

Image Courtesy:

1. “Antigen presentation” By user:Sjef – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Hematopoiesis simple” By Mikael Häggström – Own Work (CC-BY SA 3.0) via Commons Wikimedia