Smears from rat liver suspension as modified substrate for antinuclear antibody test

Immunofluorescence still remains a standard method for documenting antinuclear antibodies (ANA). Cryostat cut sections of rodent liver or Hep2 cell nuclei have been used as substrate in the test but are often difficult to arrange in laboratories in developing countries. Hence, a modification was developed using smears from rat liver suspensions. The smears were compared with the cryostat cut sections over 338 sera samples of suspected cases of collagen diseases, rheumatoid arthritis, thyroid disorders, hepatitis B, enteric fever, tuberculosis and normal subjects. The sera from suspected collagen diseases cases were also compared with ANA test using Hep2 cells. The modified smear technique was well comparable and the clarity of the immunofluorescence was even better than for cryostat cut sections. Using the modified smear technique 272 sera out of 2,851 sera gave positive test for ANA. The homogenous, speckled and peripheral patterns were seen for 203, 66 and 3 samples respectively. To conclude: The smears prepared from homogenised rat liver suspension and fixed like bacterial smears offer a very convenient and reliable tissue substrate for ANA test.