HEAT SERUM INACTIVATION AS A MANDATORY PROCEDURE FOR ANTIACTIN ANTIBODY DETECTION IN CELL-CULTURE

In autoimmune hepatitis (AIH), the smooth-muscle antibody is specific for polymerized actin. Detection of antiactin antibody (AAA) has been hampered by technical problems. We have investigated AAA in 30 sera fr om patients with Liver diseases and smooth-muscle antibody. AGA was de tected by indirect immunofluorescence in 1:40, 1:80, and 1:160 dilutio ns. Five techniques were performed using fibroblasts: with vinblastine (A); without drugs (B); with sodium citrate (C); without drugs hut wi th heat serum inactivation (D); and with sodium citrate and heat serum inactivation (E). For comparative analysis, we considered: the total number of AAA-positive sera regardless of the dilution in which reacti vity was observed, as well as in each dilution separately; and the com parison of AAA intensity between 1:40 x 1:80, 1:40 x 1:160, and 1:80 x 1:160 dilutions. AAA was more positive in techniques B, C, D, and E t han in A (P < .001) in general, and in each dilution separately. AAA w as more positive in technique I) than in B in 1:40 (P = .0005) and 1:8 0 dilutions (P = .03), as well as in E than in C (P = .0001) in 1:40 d ilution. Techniques B and D yielded results similar to C and E, respec tively. AAA staining was significantly more intense in 1:80 and 1:160 than in 1:40 dilution in A, B, and C; it was both significantly less i ntense in 1:80 and 1:160 than in 1:40 dilution and in 1:80 than in 1:1 60 in techniques D and E. We concluded that heat inactivation increase d AAA seropositivity/intensity in 1:40 and 1:80 dilutions, preventing false-negative results; actin polymerization with sodium citrate did n ot enhanced AAA seropositivity/intensity. The technique with vinblasti ne was the least effective.