Abstracts

Rasmussen encephalitis is a rare disease. In the original description, Rasmussen and co-workers attributed the disease to a possible viral infection. Later, the disease was associated with the presence of circulating anti-bodies (anti-GluR3 and anti-Munc-18) or a cytotoxic T-cell reaction against neurons. Despite all efforts in trying to better define the pathophysiology of the disease, its etiology remains quite obscure.
HLA (human leukocyte antigen) system is the human version of the major histocompatibility complex (MHC). This system encompasses genes divided in two classes, class I and class II, and both are involved in immune response. The function of these classes of molecules is the presentation of short, pathogen-derived peptides to T-cells, a process that initiates the adaptative immune response. Class I genes are expressed by most somatic cells, while class II genes are expressed by some types of immune cells like B-cells, activated T-cells, macrophages, and dendritic cells. A large group of diseases involves genes in the HLA region that are linked or associated to specific class I and class II alleles or combinations of alleles. These associations help not only to better understand some diseases but also serve as markers for several diseases, thus improving diagnosis.
So far, we were not able to find in literature HLA studies in Rasmussen encephalitis, in spite of this obvious need. This fact is probably related to the rarity of the disease. In this study we address the frequency of HLA class II antigen in all our cases of pathological confirmed Rasmussen encephalitis. After research ethical committee approval, DNA of 10 patients with pathological confirmed Rasmussen encephalitis was isolated from a blood sample and the HLA class II was typed using sequence-specific primers hybridized with DNA amplified by polymerase chain reaction (PCR), using commercially available kits. The frequency distribution of HLA class II alleles were: 1) HLA-DRB1*01: 5%, 2)HLA-DRB1*15: 15%, 3) HLA-DRB1*03: 5%, 4) HLA-DRB1*04: 10%, 5)HLA-DRB1*11: 10%, 6) HLA-DRB1*13: 25%, 7) HLA-DRB1*08: 10%, 8) HLA-DQB1*05: 20%, 9) HLA-DQB1*06: 25%, 10) HLA-DQB1*02: 10%, 11)HLA-DQB1* 03: 25%, 12) HLA-DQB1* 04: 10%. No allele was found to be significantly higher in patients with Rasmussen encephalitis when compared with ethnically matched controls. We did not observe any association of specific HLA class II genes and Rasmussen encephalitis. In spite of lack of any correlation, larger samples of patients would be necessary for a definitive conclusion. Because of the rarity of the disease, multicentric studies may be necessary. (Supported by FAPES 02/03743-0)