The prevalence of ANA in patients with chronic HCV infection in this study was 20.2%, which is significantly higher than the 2% prevalence found in healthy controls. This difference relative to the normal population is consistent with the data reported in previous studies [9, 19]. Moreover, in terms of percentage values, this prevalence is close to those found in other studies that re-ported frequencies between 19.3 and 21.3% [7, 20–23]. Even higher frequencies of ANA (between 32 and 42.6%) have been reported in patients with HCV [24–26].
The prevalence rates found in this study are well above the rates described in other studies (between 4.4 and 17.6%) [19, 27–32]. In Brazil, Narciso-Schiavon et al. [33] and Marconcini et al. [34] found prevalence rates of 9.4 and 7.6%, respectively.
Among the factors that may result in these differences, first, it must be taken into account that in most of these studies, analyses were performed on samples with a 1/40 titration, which, in theory, may increase the number of positive results due to a higher concentration of autoantibodies in the sample. Exceptions include the studies conducted by Daschakraborty et al. [22] and by Chrétien et al. [25], who analyzed samples diluted 1/80, and the studies conducted by Acay et al. [7], Łapiński et al. [23] and Kirdar et al. [31], who worked with samples diluted 1/100. Furthermore, there are differences between the substrates available in each HEp-2 cell kit, which can also generate differences in terms of pattern detection [35]. Another possibility stems from the association of fluorescence patterns with specific antibodies and differences in the susceptibility levels of different populations to develop one or another of these specific autoantibodies.
In general, the occurrence of ANA has a significantly closer association with female sex, older age and the use of some classes of drugs [36–38]. In the present study, there was a slightly higher prevalence of ANA among female patients, although this difference was not significant. Data on the role of sex in the induction of ANA in the context of chronic hepatitis C are divergent: while some studies [9, 24, 32] found a relationship between ANA seroreactivity and female sex, others [25, 33, 34] did not find such an association.
In addition, no association was found between the presence of ANA and any of the other epidemiological factors evaluated. Discordant data were found by Chen et al. [21] and by Hsieh et al. [24], who found a higher frequency of autoantibodies in older individuals. However, data similar to those in the present study were observed regarding the lack of an association of ANA with alcohol consumption [32, 33], age [34], smoking [32] and the use of injectable drugs [25].
In the present study, it was not possible to associate the presence of ANA with any of the clinical characteristics evaluated in the patients, similar to the findings of other studies [25, 27, 33, 34]. However, Lenzi et al. [19] found a higher prevalence of ANA in patients with chronic hepatitis without cirrhosis than in those with cirrhosis, the opposite of the finding in the present study, although we did not observe a significant difference.
The possibility of ANA interference in liver damage and liver function assessment tests has been reported in several studies that have shown a relationship between the presence of these autoantibodies and elevated transaminases [21, 24, 25, 33], GGT [19, 25], and globulin [20, 23, 25] levels and the reduction in the number of platelets [21, 34] in ANA-positive patients, but not ANA-negative patients, with chronic HCV infection; however, there are studies that, similar to the present study, did not observe such associations [29, 34].
Moreover, as in the present study, most studies conducted by other authors report the absence of an association between the presence of ANA and VL [9, 31, 34]. However, a study by Hsieh et al. [26] reported a higher level of ANA in individuals with a lower VL. According to the authors, this difference may result from potentially associated genetic and environmental aspects.
The histopathological analysis performed in our study showed no difference in fibrosis scores between ANA-positive and ANA-negative patients, although we observed a higher prevalence of ANA in degrees F3 and F4. In this regard, the literature provides controversial data, with reports of an association of ANA with a greater liver disease severity [24, 25, 34] as well as reports of the absence of such an association [29, 31, 33].
In the context of genotypic variability of HCV, the analysis of subgroups of ANA-positive and ANA-negative patients showed no significant differences in the distributions of HCV genotypes 1 and 3 among these subgroups. These data are in agreement with the observations reported by some authors [31, 32, 34], although there are reports of an association of genotype 1 virus infection with the presence of ANA [23, 24, 30].
Additionally, in the present study, HCV subgenotype 1a was the most frequent among ANA-positive patients, although this difference relative to the subgroup of ANA-negative patients did not reach statistical significance. This finding suggests the possibility of an association between this subgenotype and the induction of ANA in patients with chronic HCV infection. However, the limited number of subgenotype analyses in this study and the lack of data in the literature on this type of analysis do not allow confirmation of this hypothesis.
Data from different studies show that in samples from HCV-positive patients, indirect immunofluorescence (IIF) analysis in HEp-2 cells shows a predominance of nuclear fluorescence patterns and an absence of cytoplasmic pat-terns. Nuclear patterns are mainly represented by speckled patterns, with frequencies varying between 36 and 90%, much higher than those found for the other commonly associated patterns, such as the homogeneous nuclear pattern and nucleolar patterns [19, 25–27, 33, 34]. However, in our study, there was a higher prevalence of cytoplasmic patterns, and among the nuclear patterns, there was an equal frequency of homogeneous nucleolar and speckled patterns.
The CRRP is usually associated with chronic HCV infection treated with a combination of pegylated IFN and ribavirin [39–41]. However, data from other authors indicate that the ribavirin-dependent mechanism is not essential for the induction of these autoantibodies because this ANA pattern can also be detected in individuals with systemic lupus erythematosus [42], in individuals with HBV infection [39], and in clinically healthy individuals [43]. In addition, this pattern can also be induced by other drugs, such as mycophenolic acid, azathioprine, methotrexate and acyclovir [40, 44].
Existing data show frequencies of this pattern ranging from 14.1 to 37% in samples from individuals with chronic HCV infection [41, 45, 46], which are lower than the frequency (61.1%) found in the present study. These differences may result from the influence of host genetic aspects as well as from environmental factors, which may favor the formation of these autoantibodies in this region.
The epidemiological, clinical, laboratory and molecular data did not differ among patients with CRRP, CRRP-negative patients and ANA-negative patients.
Considering the CRRP-positive and CRRP-negative subgroups, some studies [39, 47, 48] did not find significant differences when considering patient age and sex. In addition, Stinton et al. [49] found no association of this ANA pattern with the use of injectable drugs. In terms of clinical characteristics, Covini et al. [45] and Da Silva Sacerdote et al. [48] found no association of this pattern with the occurrence of DM2 or the presence of cirrhosis. Similarly, Covini et al. [45] also found no association of this pattern with steatosis.
At the laboratory level, liver marker analyses performed in some studies [46, 49, 50] showed no association between the presence of CRRP and changes in biochemical tests. Molecular analyses [44, 45, 50] also did not show any association of this pattern with VL or with viral genotype.
In the present study, there was an association between the presence of CRRP and higher liver fibrosis scores, which differs from the observations reported by Climent et al. [46] and by Novembrino et al. [50], who found no similar association. This difference may be explained by the fact that, in those studies, the focus was only on patients undergoing treatment, while in our study, patients were selected using different inclusion criteria, such as not undergoing treatment at the time of data collection.
The small number of patients analyzed is a limitation of the present study. This limitation is due to the exclusion of patients from the study who had insufficient data and/or sample quantity. More generally, the discrepancies between the data available in the literature on the prevalence of ANA and its associations may be due to differences in dilutions, technical aspects, sensitivity of the laboratory methods, sample sizes, groups evaluated in each study and population-related aspects, such as genetics and environment [9, 31].