Indicate the true statements and correct the false statements so they are true.
a. B cells are activated by antigen-presenting cells.
b. T cytotoxic cells are activated by antigens bound to MHC I.
c. Upon activation, T helper cells stimulate T cytotoxic cells and B cells.
d. IgG is the first antibody made during a primary response.
e. T-dependent antigens rely on TH cells to activate B cells.

Verified step by step guidance

1. Review the role of B cells in the immune response. B cells are primarily activated by direct binding of antigens to their B cell receptors, not by antigen-presenting cells. Correct the statement: B cells are activated by direct antigen binding and T helper cells.
2. Understand the activation of T cytotoxic cells. These cells are indeed activated by antigens presented on MHC I molecules. This statement is true.
3. Examine the function of T helper cells. Upon activation, T helper cells do stimulate both T cytotoxic cells and B cells, making this statement true.
4. Consider the role of IgG in the immune response. IgG is not the first antibody produced; IgM is typically the first antibody made during a primary response. Correct the statement: IgM is the first antibody made during a primary response.
5. Explore the concept of T-dependent antigens. These antigens require the help of T helper cells to activate B cells, making this statement true.

Key Concepts

B Cell Activation

B cells are a type of white blood cell that play a crucial role in the adaptive immune response. They are activated when they encounter specific antigens, often with the help of antigen-presenting cells (APCs) that process and present these antigens on their surface. This interaction is essential for B cells to proliferate and differentiate into plasma cells that produce antibodies.

T Cell Activation

T cells, including T cytotoxic cells and T helper cells, are activated by recognizing antigens presented by Major Histocompatibility Complex (MHC) molecules on the surface of other cells. T cytotoxic cells are specifically activated by antigens presented on MHC class I molecules, which are found on all nucleated cells, while T helper cells recognize antigens presented on MHC class II molecules, typically found on APCs.

Antibody Response

The antibody response involves the production of immunoglobulins (Ig) by B cells in response to antigens. IgG is the most abundant antibody in the blood and is typically produced during the secondary immune response, while IgM is the first antibody produced during a primary response. Understanding the timing and types of antibodies produced is crucial for comprehending how the immune system responds to infections.