text: In figure at left, the various segments that form the epitope have been shown to be continuously collinear, meaning that they have been shown as sequential; however, for the situation being discussed here (i.e., the antigen recognition by the B cell), this explanation is too simplistic. Such epitopes are known as sequential or linear epitopes, as all the amino acids on them are in the same sequence (line). This mode of recognition is possible only when the peptide is small (about six to eight amino acids long), and is employed by the T cells (T lymphocytes).
  However, the B memory/naive cells recognize intact  proteins present on the pathogen surface. In this situation, the protein in its tertiary structure is so greatly folded that some loops of amino acids come to lie in the interior of the protein, and the segments that flank them may lie on the surface. The paratope on the B cell receptor comes in contact only with those amino acids that lie on the surface of the protein. The surface amino acids may actually be discontinuous in the proteins primary structure, but get juxtaposed owing to the complex protein folding patterns (as in the adjoining figure). Such epitopes are known as conformational' epitopes and tend to be longer (15–22 amino acid residues) than the linear epitopes.  Likewise, the antibodies produced by the plasma cells belonging to the same clone would bind to the same conformational epitopes on the pathogen proteins.
  The binding of a specific antigen with corresponding BCR molecules results in increased production of the MHC-II molecules. This assumes significance as the same does not happen when the same antigen would be internalized by a relatively nonspecific process called pinocytosis, in which the antigen with the surrounding fluid is "drunk" as a small vesicle by the B cell. Hence, such an antigen is known as a nonspecific antigen and does not lead to activation of the B cell, or subsequent production of antibodies against it.