Question

You have become infected with a pathogenic parasite Assicus baddus. If this parasite invades hepatic cells and inhibits MHC expression, what type of immune response is needed to eliminate this pathogen? Explain your response including specific types of molecules or cells involved

Answer 1

A cytotoxic T-cell response is required to eliminate the pathogenic parasite Assicus baddus that inhibits MHC expression, but natural killer (NK) cells may compensate when MHC class I expression is suppressed.

Step-by-step explanation:

To eliminate the pathogenic parasite Assicus baddus that inhibits MHC expression on hepatic cells, a cytotoxic T-cell immune response is needed. Since the parasite suppresses MHC class I molecule presentation necessary for engaging cytotoxic T cells, cells infected by the parasite cannot be recognized and targeted by the usual immune response.

Professional antigen-presenting cells, which normally process and present antigens on MHC class I to cytotoxic T cells for the elimination of intracellular pathogens, are hampered in this scenario. However, natural killer (NK) cells have the ability to recognize and respond to cells with diminished MHC class I expression. Upon identifying these infected cells, NK cells can induce apoptosis, leading to the destruction of the pathogen-infected cells.

This immune response does not rely on antigen presentation via MHC but instead utilizes a mechanism that identifies and destroys cells that fail to properly display MHC class I molecules, which is a common sign of infection or cellular stress.