Answer
Helper T cells initiate the immune response by identifying the foreign antigen.
Cytotoxic T cells kills the infected cells by cell lysis. They secrete degradative enzymes in the infected cells to kill them.
Regulatory T cells suppresses the activity of lymphocytic cells. After the antigen is removed they sends out chemical signals to prevent overstimulation of lymphocytic cells.
In the body of a person suffering from AIDS his helper T cells are disable by HIV. HIV attaches to the helper T cells and it's antigen recognition is reduced or disabled. Due to this the immune response of the body can not be initiated and even easily suppressed pathogens becomes very dangerous.
Work Step by Step
Same as above.
