Question

Which cell of the immune system is absolutely required for an adaptive immune response in that it helps activate both humoral and cellular immune responses?

1) B cell
2) T cell
3) Natural killer cell
4) Macrophage

Answer 1

The T cell, especially the helper T cell, is essential for the adaptive immune response, as it helps activate both humoral immunity (through B cells) and cellular immunity (through cytotoxic T cells).

Step-by-step explanation:

The cell of the immune system that is absolutely required for an adaptive immune response is the T cell, particularly the helper T cell. Helper T cells are crucial for activating both humoral and cellular immune responses. They facilitate the activation of B cells, which are involved in producing antibodies for the humoral response, and cytotoxic T cells, which kill virus-infected cells as part of the cellular immune response. Furthermore, helper T cells enhance the function of macrophages and natural killer cells, contributing to the overall immune defense.

In summary, while macrophages and natural killer cells are important for presenting antigens and providing initial defense respectively, and B cells produce antibodies, it is the helper T cells that are essential for orchestrating the adaptive immune response. Therefore, among the options provided, T cells (Option 2) are the correct answer.