Immunological characterization of the nuclear pattern designated "quasi-homogeneous pattern" observed by the indirect immunofluorescence technique in HEp-2 cells

• Grant number: 09/52234-0
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2009
• End date: August 31, 2011
• Field of knowledge: Health Sciences - Medicine
• Principal Investigator: Luiz Eduardo Coelho Andrade
• Grantee: Luiz Eduardo Coelho Andrade
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Several autoimmune rheumatic diseases present autoantibodies (AAb) capable of recognizing various cell antigens. Some AAb keep a very close association with a given disease and are considered markers of this disease, such as anti-Sm and anti-native DNA which are markers of systemic lupus erythematosus, and extremely unlike to occur in healthy individuals. Other AAb appear indiscriminately in different autoimmune, infectious, and neoplasic diseases, although with variable titles and frequencies. There are also AAb that appear with reasonable frequencies in healthy individuals. The search for antinuclear antibodies by indirect immunofluorescence (IIF) in HEp-2 cells (ANA HEp-2) is one of the major methods for autoantibody screening. The fluorescence pattern observed in the ANA HEp-2 test reflects the distribution of the recognized self-antigen, and is therefore relevant to the knowledge of the autoantibody target. Although some fluorescence patterns may be relatively nonspecific, others may provide an indication of the possible AAb in the sample. Thus, ANA-HEp-2 test is a very important tool for AAb screening, suggesting the possible AAb involved, reducing the efforts needed for its identification, and avoiding unnecessary costs. Our group has been able to identify and describe several relevant associations of ANA-HEp-2 fluorescence patterns (Andrade et al, 1991; Andrade et al, 1996; Dellavance et al, 2005; Dellavance et al, 2009). Recently a new pattern, which closely resembles both the homogenous and the dense fine speckled nuclear patterns, has been observed in our routine laboratory. This pattern was designated "nuclear fine speckled tending to homogeneous" (PFH) pattern. Due to the frequent presence of the PFH pattern in routine AAb screenning, this study aims at its immunological characterization, investigate the target antigen(s) involved and evaluate possible clinical associations. (AU)