Antinuclear antibody positivity Extractable nuclear antigen positivity 2021-01-09T22:51:15Z This is a group of autoantibodies against autoantigens that can be extracted from the cell nucleus with saline. The ENAs consist of ribonucleoproteins and non-histone proteins, named by either the name of the donor who provided the prototype serum (Sm, Ro, La, Jo), or the name of the disease setting in which the antibodies were found (SS-A, SS-B, Scl-70). The presence of autoantibodies in the serum that react against extractable nuclear components that are referred to as extractable because they can be extracted from cell nuclei with saline solution.