Are antibody molecules present freely in the connective tissue?
Some of them are, but others- aren’t. An antibody is a glycoprotein that interacts specifically with an antigenic determinant. Antibodies belong to the immunoglobulin (Ig) protein family. Free molecules of antibodies are secreted by plasma cells that arise by proliferation and terminal differentiation of clones of B lymphocytes whose receptors recognize and bind specific epitopes. These secreted antibodies either circulate in the plasma and may leave the blood vessels reaching the tissues or are present in the secretion of some epithelia (eg, of the mammary gland and salivary glands). Other antibodies are not free molecules, but are integral membrane proteins of the surface of lymphocytes. In any case, each antibody combines with the epitope that it specifically recognizes.
