i never understand why b ams t lymphocyte doesnt kill own body cells ?

Hello

Let's understand the concept in layman terms. Every cell be it human cell be it bacterial cell contain a specific antigens which like a lego block which can be fixed to another complementary lego. So as these antigens are presented to antibodies who can fixed to only a specific shape of antigens it will only recognize these specific cells. The immune cells such as T and B cell ultimately lead to the formation of antibodies.

For example the bacteria cells have triangle shapes antigen and the cells of the humans body have square shaped antigen. The antibodies formed by the body against the bacteria is only attaches to triangle shaped objects so it will only attack the bacteria and the body cells are left unaffected.

Of course it is to be notes there a numerous antigens, with very complex structures making them distinguishable in each type of cells.

In some cases the antigens of a foreign body and a human cell antigen may be very similar. In that case the antibody formed against the foreign body might attack human cell itself and that will lead to autoimmune diseases.

h ope this would help

thank you

Hello!!

you know that there are two kinds of aggranulocyte which is basically responsible for providing adaptive immunity and these fights against foreign materials that is antigen,these are T-LYMPHOCYTES AND B-lymphocytes,b-lymphocyte is formed in bone marrow whereas t-lymhocyte is formed in bone marrow but it's maturation takes place in thymus during maturation these cells are taught to recognise self cells through MHC recognition,thus they know howmto differentiate.