An antigen presenting cell presents antigen to a t-lymphocyte is called

An antigen presenting cell present antigens to helper t lymphocyte is called Macrophage.

Explanation:

Macrophage belong to the family of antigen presenting cell. Macrophage along with the help of low molecular weight protein cytokines migrates to the site of inflammation. After reaching that site Macrophage engulf the antigen and destroy the later by the process called cell eating or phagocytosis.

                                  Then the antigenic fragements are presented to Helper T cell with the help of a protein molecule known as Major Histacompatability complex or MHC.

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.