Question

what is the difference between T dependent antigen and T independent antigen?

Answer 1

T-independent antigens are antigens which can directly stimulate the B cells to produce antibody without the requirement for T cell help In general, polysaccharides are T-independent antigens. The responses to these antigens differ from the responses to other antigens.
T-dependent antigens are those that do not directly stimulate the production of antibody without the help of T cells. Proteins are T-dependent antigens.

from: http://pathmicro.med.sc.edu/mayer/antigens2000.htm

Answer 2

T dependent requires T helper cells and the secretion of cytokines. Cytokines are needed for clonal expansion of B cells and Macrophage activation