Question

Write a short note on B cells?

Answer 1

The defence mechanism provides protection against specific foreign materials and is often called the immune system.

Complete step by step answer:
-Lymphocytes are the main cells of the immune system.
-They, like other blood corpuscles, arise from the stem cells , the hemocytoblasts, present in the liver in the foetus and in the bone marrow in the adult.
-Some of them undergo differentiation in the gut associated bursal lymphoid tissues (tonsils, peyer patches, appendix) and are called bursal or B lymphocytes, others are differentiated in the thymus gland and are termed thymus or T Lymphocytes.
-The mature lymphocytes pass into the body fluids ( blood and lymph ) and circulate in the body. Many of them stay in the lymph nodes.
-B cells form humoral or antibody- mediated immune system (AMIS)
-They defend against some viruses, encapsulated bacteria and toxins that enter the blood and lymph.
-They form by division plasma cells.
-Plasma cells do not move to the site of infection. Plasma cells secrete antibodies that pass into the blood and lymph and dispose of the antigens.
-Plasma cells do not react against transplants and cancer cells.
-Plasma cells have no inhibitory role on the immune system.

Additional information:
-T cells form cell mediated system (CMIS)
-They are differentiated in the thymus gland.
-They defend against viruses, protists, fungi and some bacteria which enters the cells
-They form by division lymphoblasts of three types: killer, helper and suppressor cells.
-Lymphoblasts move to the site of infection. Killer cells on reaching the site of infection secrete perforin that kills microbes by puncturing their cell membrane.
-Killer cells react against transplants and cancer cells also.

Note:
Suppressor cells inhibit the immune system from attacking the body's own cells.Both the immune system needs antigens to come into action, but they respond in different ways.