Question

1. All the following represent characteristics of the adaptive immune system EXCEPT:

1. all the above is true, no exceptions
2. secondary response characterized by rapid destruction of the pathogen
3. recognition by pattern recognition receptors
4. development of memory response
5. recognition of individual antigens and epitopes

1. Intravenous immunoglobin therapy is being used as a treatment for severely affected Covid-19 patients. This infusion of antibody isolated from the blood of individuals who recovered from the infection would predominantly be which class of antibody?

1. IgS
2. None of the answers are correct
3. IgG
4. IgM
5. IgD
6. IgB

1. Immunoglobulins consist of four polypeptides; effector functions result when certain immune system components

1. Interact with the variable domains of both the light chains
2. Interact with the variable domains of both the heavy chains
3. Interact with the constant domains of both the light and heavy chains
4. Interact with the constant domains of both the light chains
5. None of the above

1. Which of the following apply to T_h cell recognition and response to antigen?

1. Recognition of antigen displayed by MHC I with secretion of cytokines in the presence of IL-2
2. Recognition of PAMPs by the col-like receptors
3. Recognition antigen in the absence of MHC molecules with secretion of antibody
4. None of the answers apply
5. Recognition of antigen displayed by MHCI with secretion of cytokines that include IL-2

Answer 1

The adaptive immune system depends on fewer type cells like B and T lymphocytes. These are derived from multipotent hematopoietic stem cells of the bone marrow. The B cells differentiate into plasma cells that produce antibodies. The memory B cells activated immediately during secondary encounter of the pathogen and eliminate pathogen from the body. The T lymphocytes differentiate into T helper cells, T cytotoxic cells and regulatory cells and these cells express CD4, CD 8 and CD8 receptors respectively for binding and neutralizing the antigens. The natigens bind to specific epitopes are recognized by the adaptive immune cells. Therefore, option a is correct.

The convalescent plasma therapy is approved by FDA and WHO in some countries for treatment of covid-19. This is because the treatment was earlier successful in treatments of infections caused by Ebola virus and SAARS- CoV 2 virus and some other viral infections. The convalescent plasma is collected from recovered patients of covid - 19 infection. The plasma contains antibodies mainly the IgG. The intravenous infusion of convalescent plasma with IgG antibody could make better treatment option at present for covid-19 infection as there is no vaccine available currently. Therefore, option c is correct.

The immunoglobulins are class of proteins and are known as antibodies. These molecules are polypeptides composed of four peptides including two identical heavy and two light chains. The antibody molecules thus appear in letter 'Y' shape. Each heavy chain covalently binds with the other by one or two disulfide bonds. One light chain linked with heavy chain by disulfide bond. The immunoglobulin contains constant and variable domains. Each immunoglbulin contains a variable domain at amino terminal end. Each immunoglobulin contains one constant domain on light chain and three to four constant domains on heavy chains. The antigen binding sites occur pairs of heavy and light chains at the end of Y shaped molecule. The variable domains have different amino acid composition and contribute to diversity of antibodies so that they can bind with specific antigen. The constant domains are highly conserved and interact with components of immune system for effective function of destruction and elimination of pathogens. Therefore, option c is correct.

The T helper cells have CD4 receptors that bind with class II MHC and their function is to secrete cytokines and enhance immune activity. The Th1 cells secrete cytokine and regulate immune activity by inducing macrophages. The Th2 cells are cytokine producing cells which act on B lymphocytes and differentiate to plasma cells to drive antibodies formation. Therefore, option d is correct.