molecules, the antibodies tend to aggregate the antigens which can then be easily engulfed by macrophages in the lymphoid tissues. In contrast, T lymphocytes, arise from those lymphoid stem cells in the thymus. T lymphocytes usually attack antigens that are located on the membranes of invading cells, such as bacteria, thus, providing the body with a cell-mediated immunity. Antibody-antigen combinations attract complement (blood proteins) which provides binding sites for macrophages and may help lyse the invading cells.
