Anti-nuclear antibodies (ANA): antibodies against nuclear components of cells, a screening test for rheumatic diseases. low titers of ANA can be found in infections, tumors and normal subjects, ANA > 1:80 has clinical significance. positive ANA may not have a parallel relationship with disease activity, even high titers of ANA do not necessarily indicate severe disease. There are five types of fluorescence: 1) homogeneous: associated with anti-histone antibodies; 2) speckled: associated with anti-soluble nuclear antigen antibodies; 3) nucleolar: associated with anti-nucleolar RNA and anti-RNA polymerase I antibodies, etc., which are more common in scleroderma; 4) perinuclear: associated with anti-DS-DNA antibodies; 5) mitotic: associated with Raynaud’s phenomenon.