Question

Naive lymphocytes go through a three-step activation process. The stimulus in the final step is provided by a(n):

Question 8 options:

	helper T cell
	antibody
	macrophage
	dendritic cell

The activation of naive helper T cells is typically initiated by a(n):

Question 9 options:

	histamine molecule
	B cell
	dendritic cell
	macrophage

Answer 1

8. Naive lymphocytes mean those lymphocyte which have no history of contact with antigen. Naive lymphocytes are of two type viz B lymphocyte produce in bone marrow and T lymphocyte produce in thymus. After maturation they migrate to the secondary lymphoid organ where they get contact with the antigens.

Helper T cell does not kill the antigen directly. It bind with the T CELL RECEPTOR of MHC class II antigen gen complex. This trigger the activation of the cytotoxic T cell and the B cell . Cytotoxic T cell kill the antigen and the B cell produces antibody or become the memory cell.

Helper T cell also stimulate the macrophages to kill the antigen by phagocytosis and the Dendritic cell is a APC which activate the helper T cell.

So the right answer is HELPER T CELLS .

9.  Helper T cells is also known as CD4+ cells. They help in the addaptive immunue responce by activating other Cells such as macrophages, cytotoxic T cells. They also regulates the immunue responce in body.

As being T cell , It is produced in Thymus and migrates to lymph node . The professional antigen presenting cell binds with the antigen and shows the MHC II antigen complex on there surface and reaches to the lymph node. In lymph node there is Helper T cell which recognise the antigen complex and gets activates to stimulate the other cells to kill the pathogen.

So that the Helper T cell is activated by the ANTIGEN PRESENTING CELLS. In given option the most prominent antigen presenting cell is the Dendritic Cell.

Histamine is produced by the basophils which kill the allergen molecules.

Macrophages some time work as apcs but it is activated by Helper T cell.

B cells are the memory cells .

So the right answer is  DENDRITIC CELLS.