Question

1. TCRs do not act directly against antigens but trigger a signaling cascade inside the T-cell for further actions.
2. What are the molecules in addition to the TCR that T cells use to initiate their responses to antigens, and what are the functions of these molecules?

Answer 1

The immune system provides protection against invasion of microorganisms from outside the body. T and B lymphocytes are necessary for a normal immune response. Immunoglobulin like IgG,IGm are also available to give protection against harmful microorganisms.

The function of thymus is to produce lymphocytes. In the thymus the lymphocytes acquire new surface antigens. (Thy antigens).

Lymphocytes conditioned in the thymus called T cells.

Lymphocytes migrate to lymphoid tissue where they remain dormant until they need to form sensitized lymphocytes for cellular immunity or antibodies for humoral immunity.

The reaction of an immunity competent cell to its specific antigen may be induction of either tolerance or the immune response.

TYPES OF T CELLS.

1.T helper cells.

2.Supressor cells.

3.Cytotoxic /T cells.

4..Memory cells.

1.T helper cells.

It have CD4 surface marker.it stimulates and promote the growth of T cells and macrophages.

Based on different profile of cytokines produced it is of 2 TYPES.TH1 adTH2.

TH1 cells produce mainly the cytokines interferon gamma and interleukin 2 (IL2).function is to activate macrophages and T cells promoting cell mediated immune response,destruction of target cells and killing of intracellular microbes.

TH2 cells produce mainly the cytokines, IL4,5, and 6. Its function is to stimulate B cell to form antibodies.

2.Supressor cells.

They have CD8 surface marker and MHC class1 restriction function is to regulate immune response and check over stimulation.

3. T cells.

The function is to kill and lyse target cells carrying new or foreign antigens.

4. memory cells.

They have both CD4 and CD8 cells. function is to provide memory and anamnestic immune response.

B lymphocytes are also helps to protect immune system.

T cells helps us to maintain our health .it gives protection against harmful microorganisms by using quick immune response.