Question

what are t-cells and t-cytotoxic cells?​

Answer 1

Helper T cells do not directly kill

infected cells, as cytotoxic T cells do.

Instead they help activate cytotoxic T

cells and macrophages to attack

infected cells, or they stimulate B cells

to secrete antibodies. Helper T cells

become activated by interacting with

antigen-presenting cells, such as

macrophages. Antigen-presenting cells

ingest a microbe, partially degrade it,

and export fragments of the microbe

i.e., antigens-to the cell surface, where

they are presented in association with

class II MHC molecules. A receptor on

the surface of the helper T cell then

binds to the MHC-antigen complex. But

this event alone does not activate the

helper T cell. Another signal is

required, and it is provided in one of

two ways: either through stimulation by

cytokine or through a costimulatory

reaction between the signaling protein,

B7, found on the surface of the

antigen-presenting cell, and the

receptor protein, CD28, on the surface

of the helper T cell. If the first signal

and one of the second signals arereceived, the helper T cell becomes

activated to proliferate and to stimulate

the appropriate immune cell. If only the

first signal is received, the T cell may

be rendered anergic—that is, unable to

respond to antigen.

______________________________

mark as brainliest answer.