What are the 3 main kinds of cells involved in acquired immunity? Briefly give t

Question

What are the 3 main kinds of cells involved in acquired immunity? Briefly give the function of each cell type. d. Which of the above given cell types will be directly involved in the attack on virus infected cells? e. Will the same type of immune cell be as effective against cells infected with a eukaryotic intracellular parasite? Which cell junctions in animals have a function comparable to the plasmodesmata in plants? Mention at least 3 structural differences between the two types of cell connections.

Explanation / Answer

27).

Adaptive immunity provides specific immunity against particular pathogens (generates specific antibodies) and is acquired after birth. This includes the generation of memory B cells, which can specifically act against particular pathogens upon their second exposure onwards.

The following are the defining characteristics of adaptive immunity:

1). Acquired after birth.

2). Differentiates between self and non-self-cells and provides specific immunity against a selective pathogen.

3). Response is late

4). Memory cells are stored for each specific pathogen, and the attack is very diverse and specific.

5). Response speed increases with successive exposure (this is due to immunological memory).

6). Attack occurs from second exposure onwards.

The acquired or the adaptive immunity includes both the cell-mediated and antibody-mediated immunity. The major cell types are give below.

T cells – Tc (cytotoxic T-cells):

Cytotoxic T cells (TC) are mainly involved in cell-mediated immunity. They attack the virus infected cells, cancerous cells or any foreign cells by direct contact with them.

Cytotoxic T cells: The cytotoxic T cells or TC cells can differentiate into CTL (cytotoxic T lymphocytes). Actually, these TC cells cannot kill the cells, but they are the precursors of CTLs that can recognize and attack the non-self-target cells. The antigens processed by the dendritic cells can be recognized by the CTL cells, finally killed by apoptosis. These target cells are non-self-cells or cells that are already infected by a pathogen or virus (as in case of hepatitis B).

Th (Helper T-cells): The T-helper cells contain CD4 molecules on the surface and mainly releases cytokines and these cells bind to the MHC II surface proteins. They do not directly attack the infected cells; they activate the cytotoxic T cells and macrophages, which can directly attack the infected cells. They recruit other white blood cells and organize an immune response.

B cells:

Plasma cells: Under the stimulation of cytokines, B cells differentiate into plasma cells that are capable of secreting antibody molecules about 100million per hour (per each plasma cell).

Memory B cells:

Adaptive immune response generates memory B cells, which can specifically act against particular pathogens upon their second exposure onwards. Memory B cells are not produced by innate immune response, which is non-specific rapid immune response

d). The cells infected with the viruses are attacked by the Th cells.

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