Although mature lymphocytes all look pretty much alike, they are extraordinarily diverse in their functions. The most abundant lymphocytes are:
B lymphocytes (often simply called B cells) and
T lymphocytes (likewise called T cells).
Some of the differences between B Cells and T Cells are as follows:
|Outside Lymph Node
|Interior of Lymph Node
|BCR (= immunoglobulin) for antigen
|TCR for antigen
|B-cells can connect to antigens right on the surface of the invading virus or bacteria.
|T-cells can only connect to virus antigens on the outside of infected cells.
|Germinal centres of lymph nodes, spleen, gut, respiratory tract; also subcapsular and medullary cords of lymph nodes
Parafollicular areas of cortex in
nodes, periarteriolar in spleen
|Life span is short
|Life span is long
|Surface Antibodies present
|Absence of surface antibodies
|They secrete antibodies
|They secrete Lymphokines
|В-cells form humoral or antibody-mediated immune system (AMI).
|T-cells form cell-mediated immune system (CMI).
|20% of lymphocytes
|80% of lymphocytes; CD4 > CD8
|They form plasma cells and memory cells.
|They form killer, helper and suppressor cells.
|Movement to Infection Site
|Plasma cells do not move to the site of infection.
|Lymphoblasts move to the site of infection.
|Plasma cells do not react against transplants and cancer cells.
|Killer cells react against transplants and cancer cells.
|Plasma cells have no inhibitory effect on immune system.
|Suppressor cells inhibit immune system.
|They defend against viruses and bacteria that enter the blood and lymph.
|They defend against pathogens including protists and fungi that enter the cells.