Question 1

What is the Meaning of MHC Class II?

Accepted Answer

MHC Class II molecules are specialized cell surface glycoproteins found primarily on professional antigen-presenting cells, vital for adaptive immunity. They bind and present externally derived peptide antigens, such as those from pathogens, to CD4+ T helper lymphocytes. This interaction initiates specific immune responses, enabling the body to effectively identify and respond to foreign threats.

Question 2

What is the Context of MHC Class II?

Accepted Answer

These molecules operate within the immune system, specifically on macrophages, dendritic cells, and B lymphocytes. When these cells internalize foreign material, they process it into peptide fragments. MHC Class II molecules then display these peptides to T helper cells in lymphoid tissues, essential for coordinating immune responses.

Question 3

What is the Significance of MHC Class II?

Accepted Answer

MHC Class II molecules are fundamental for immune tolerance, distinguishing self from non-self. Dysfunctional forms are implicated in autoimmune diseases like Type 1 Diabetes and Celiac Disease, where the immune system targets body tissues. Genetic variations also influence susceptibility to infections and organ transplantation success.

Question 4

What is the Mechanism of MHC Class II?

Accepted Answer

Exogenous antigens are internalized and degraded into peptides within acidic endosomal compartments. MHC Class II molecules, with an invariant chain, prevent premature peptide binding. This chain degrades in the endosome, allowing antigenic peptides to bind. The stable complex then moves to the cell surface, engaging T-cell receptors on CD4+ T helper cells for activation.

Question 5

What is the Application of MHC Class II?

Accepted Answer

HLA typing, assessing an individual's MHC Class II genetic profile, is essential in clinical transplantation for compatibility and minimizing graft rejection. This knowledge also informs vaccine design by identifying antigenic peptides that optimally bind to common MHC Class II alleles, eliciting robust T helper cell responses. Specific alleles also serve as diagnostic markers for autoimmune conditions, guiding personalized management.

Question 6

What is the Metric of MHC Class II?

Accepted Answer

MHC Class II expression on cell surfaces is quantified using flow cytometry with specific fluorescent antibodies. Genetic assessment, Human Leukocyte Antigen (HLA) typing, determines specific alleles encoding MHC Class II genes within an individual's genome. This is critical for tissue matching in transplantation and evaluating autoimmune disease risk. Functional assays can also evaluate antigen-presenting cell capacity to present peptides.

Question 7

What is the Risk of MHC Class II?

Accepted Answer

Dysregulation in MHC Class II expression or function carries substantial clinical risks. Genetic variations are strongly linked to increased susceptibility to autoimmune disorders, where inappropriate immune responses against self-antigens lead to chronic inflammation and tissue damage. In organ transplantation, MHC Class II mismatch drives graft rejection, necessitating intensive immunosuppressive regimens. Mismanagement can profoundly impact long-term health outcomes.

MHC Class II

Meaning

Context

Significance

Mechanism

Application

Metric

Risk

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