Read the following passage carefully and answer the given questions.

The B-lymphocytes produce an army of proteins in response to pathogens. Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy chains. Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection. Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing. The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy. Lymphoid organs are the organs where origin and/or maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus. After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix. Heroin commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound. This is obtained by acetylation of morphine, which is extracted from the latex of poppy plant Papaver somniferum.

Which one of the following is not a feature of an antibody:

T-lymphocytes produce antibodies in response to pathogens in our blood to fight with them

The correct answer is Option (4) –T-lymphocytes produce antibodies in response to pathogens in our blood to fight with them

Antibodies, also known as immunoglobulins, are protein molecules produced by B-cells as part of the immune response. Each antibody consists of several polypeptide chains. The structure of an antibody includes two types of chains: light chains and heavy chains.

Antibodies have four polypeptide chains in total. There are two small chains called light chains. The small chains are referred to as light chains.  Antibodies have two longer chains called heavy chains. The longer chains are referred to as heavy chains.  The antibody structure is represented as H₂L₂, indicating two heavy chains and two light chains. The two heavy chains are linked to each other by disulfide bonds and each heavy chain is linked to a light chain by a disulfide bond. 

The B-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them. These proteins are called antibodies. The T-cells themselves do not secrete antibodies but help B cells to produce them. Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy chains. Hence, an antibody is represented as H2 L2 . Different types of antibodies are produced in our body. IgA, IgM, IgE, IgG , IgD are antibodies . Because these antibodies are found in the blood, the response is also called as humoral immune response .