||B lymphocytes (B cells)
||T lymphocytes (T cells)
||Site of Maturation
||B lymphocytes both originate and mature in the bone marrow.
||T lymphocytes mature in the thymus after its origination in the bone marrow.
||Mature B cells occur mostly outside the lymph node.
||Mature T cells occur mostly inside the lymph node.
||Germinal centers of lymph nodes, spleen, gut, respiratory tract; also subcapsular and medullary cords of lymph nodes.
||Parafollicular areas of cortex in lymph nodes, periarteriolar in the spleen.
||The B-cell receptors (BCRs) constitute of membrane antibodies known as immunoglobulin surface receptors.
||Surface receptors are called T-cell receptors (TCRs) and differ from membrane antibodies.
||Extracellular antigens such as bacteria, free viruses and other circulating free foreign material.
||The foreign antigen in association with self-antigen only such as a virus-infected cell.
||The need of Antigen Processing
||Antigen processing is not necessary.
||Antigen processing is necessary.
||They bind directly with the antigens on the surface of the invading virus or bacteria.
||They can only bind to antigens on the outside of infected cells and not directly.
||C3 complement receptor
||Receptors for C3 complement present.
||Receptors for the C3 complement are absent.
||Cell Surface Marker
||CD19 is the cell surface markers of B cells.
||CD3 is the cell surface markers of T cells.
||Microvilli on the cell surface
||Types of Active Cells
||They differentiate into plasma cells and memory cells.
||They differentiate into many subsets of T cells such as Cytotoxic T cells (CD8+ T cells), Helper T cells (CD4+ T cells) and suppressors cells along with memory cells.
||It constitutes about 20% of lymphocytes in the blood.
||It constitutes about 80% of lymphocytes in the blood.
||Antibodies are the chief secretory product of B cells.
||Cytokines (lymphokines) are the chief secretory product of T cells.
||Type of Immunity
||Involved in humoral (antibody-mediated) immunity.
||Involved in cell-mediated immunity.
||They have comparatively a shorter life span.
||They have a comparatively longer life span.
||Since B cells are also Antigen Presenting cells, they present antigens to T-cells.
||They help to activate B cells and aid in antibody production against antigens which are T-dependent.
||Help eliminate free foreign invaders by enhancing immune responses against them; provide immunity against most foreign antigens and bacteria.
||Help lyse virus-infected cells and tumor cells; provide immunity against most viruses and intracellular bacterial pathogens; help B cells in antibody production.