It is well known that any test such as antibodies against a specific antigen conveys false positive and false negative results. This can lead to diagnostic and therapeutic errors by utilizing measures when they are not required [23,24]. In this analysis, we see that using clinical criteria before requesting the test provides a considerable improvement in the diagnostic workup. Antibodies considered to be specific for SLE, such as double strand anti-DNA, have been reported as well in Sjogren’s syndrome, dermatomyositis and cutaneous sclerosis [[25], [26], [27], [28] and [29]]. In our series the percentage of SLE patients with positive ANA was of 49%, with varying frequency ranges

from 6% to 50%, when SLE coexisted with other diseases, and in 90% of patients with renal damage, a finding known to bear a worse prognosis [[30], [31], check details [32] and [33]]. Protein Tyrosine Kinase inhibitor In non-rheumatic diseases we found anti-DNA antibodies in frequencies similar to those previously reported in the literature, supporting the idea of the existence of

an immunological alteration in cardiovascular and renal diseases, which might be explained by previous infections [15,34,35]. Antibodies directed towards ribonucleoproteins (SM, RNP, SSB) are usually detected in SLE, but not in discoid lupus. Our results concur with previous literature [31,36]. As for SM antibodies, there are reported presence of them in 15–40% of cases; we found that they are present in 30% of cases of SLE when not associated with other diseases, with ranges that vary from 15% to 50% when another SRD coexists with SLE or there is damage to a specific organ [37,38]. Quite remarkable,

elevated ANA titers are important in the diagnostic of rheumatic diseases, but it is also very important to be familiar to each laboratory’s cut-off points. Also the type of pattern of antibodies was found in some cases in close correlation with the presence of some autoimmune diseases. It is known that antibodies directed against ribonucleoproteins are associated with connective tissue diseases [39]. An homogeneous pattern might be proof of reaction against native single STK38 or double stranded DNA and associated with SLE. The centromeric pattern is characteristic of CREST syndrome and those against nucleolar RNA are associated with SLE and systemic progressive sclerosis [40]. However, other unusual nuclear ANA are those against the nuclear mitotic apparatus (NuMA), which might or might not be reported accurately depending upon the laboratory’s experience [41]. Their positivity is associated with connective tissue disease, 45% corresponding to Sjogren’s syndrome and undifferentiated connective tissue disease as well as autoimmune diseases against specific organs in 17% even though up to 38% have been found in non-autoimmune diseases [42]. In this study 2% of patients had NuMA, and they were associated with primary AS, one of them with optic neuritis and a possible Devic syndrome.