T cells and the humoral immune system

Lymphoid cells and macrophages play an important role in the development and rnaintance of humoral and cellular immunity in mammals. The lymphoid cells in the peripheral lymphoid organs are divided into two major classes: (1) thymus-derived lymphocytes or T cells and (2) bursa-equivalent-derived lymphocytes or B cells. Humoral immune responses to most antigens require interaction between macrophages, T cells and B cells. Antigen-stimulated T cells do not produce antibodies but secrete regulatory substances which have a stimulating or a suppressive effect on the differentiation of antigenstimulated B cells into antibody-producing plasma cells. The macrophage plays an important role in this T-B interaction by concentrating the antigen by endocytosis and presenting a part of it in a persisting immunogenic form on its cell membrane. Several aspects of the regulatory influence of the T cell on the humoral (B) immune system were investigated in our laboratory and the results of our experiments are presented in the papers added to this thesis.