title: Cellular immune response to β2-glycoprotein-I valine/leucine247phenotypes in Mexican patients with primary antiphospholipid syndrome.
abstract: Homozygote genotype V247of the β2-glycoprotein-I (β2GP-I) gene has been associated with anti-β2GP-I and thrombosis in patients with primary anti-phospholipid syndrome APS (PAPS). However, the cellular immune response to β2GP-I247has been little studied.
  
  
  OBJECTIVE
  To evaluate the immune cellular proliferation in response to native and non-native β2GP-I247valine/leucine phenotype from Mexican patients with PAPS.
  
  
  METHODS
  We studied 10 patients with PAPS and 10 healthy control subjects (HC). The polymorphism at position 247 of the β2GP-I gene was determined by PCR-RFLP and the corresponding β2GP-I protein was subsequently purified from normal human plasma by affinity chromatography. PBMC purified from patients and controls were stimulated with β2GP-I under native and in non native (reduced) conditions. We also determined the anti-β2GP-I production in vitro by B cell clones (EBV) generated in cocultures experiments. Differential Scanning Calorimetry (DSC) was studied to determine the structural differences between the β2GP-I247valine/leucine isoforms. Cytokine profile (IL-2, IL-4, IL-6, TNFα, INFγ) was evaluated in culture supernatants.
  
  
  RESULTS
  PAPS and healthy control PBMCs had a higher proliferative response when stimulated with β2GP-I under reduced cultures conditions compared to non-denatured conditions. PBMCs response from PAPS patients was higher. We observed more cell proliferation in response to β2GP-I247valine/leucine or valine isoforms in non-native conditions. In contrast, this response was not significant against β2GP-I247leucine. These findings were T CD4+-dependent. Similar results were obtained with B cell clones derived from PAPS patients, which showed more pronounced proliferation in non native conditions and higher against β2GP-I247valine. No differences were found in anti-β2GP-I production, but high levels of IL-6 in vitro were identified. The structural analysis of both β2GP-I247isoforms by DSC showed a major conformational change due to a single mutation in the β2GP-I variants.
  
  
  CONCLUSIONS
  PAPS PBMCs had a higher cellular response against β2GP-I247in non-native culture conditions preferentially to the β2GP-I247valine phenotype. This effect is T CD4+dependent and appears to be driven by tertiary structural changes adopted by β2GP-I247polymorphism.
authors.affiliation: Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Núñez-Álvarez
authors.affiliation: Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.
authors.forename: Diego F
authors.initials: DF
authors.lastname: Hernández-Ramírez
authors.affiliation: Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.
authors.forename: Araceli
authors.initials: A
authors.lastname: Martinez-Castillo
authors.affiliation: Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.
authors.forename: Virginia
authors.initials: V
authors.lastname: Pascual Ramos
authors.affiliation: Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Cabiedes
authors.affiliation: Department of Biochemistry, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico; Department of Biochemistry, Instituto Nacional de Perinatología, Mexico City, Mexico. Electronic address: aortega@unam.mx.
authors.forename: Alicia
authors.initials: A
authors.lastname: Ortega
authors.affiliation: Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico. Electronic address: arcabral1952@gmail.com.
authors.forename: Antonio R
authors.initials: AR
authors.lastname: Cabral
mesh_terms: D000328:Adult; D016736:Antiphospholipid Syndrome / Q000235:genetics* / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002999:Clone Cells; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005838:Genotype; D006801:Humans; D007111:Immunity, Cellular; D007930:Leucine; D008297:Male; D008800:Mexico; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011110:Polymorphism, Genetic; D014633:Valine; D053482:beta 2-Glycoprotein I / Q000235:genetics*
chemical_list: D016207:Cytokines; D053482:beta 2-Glycoprotein I; D007930:Leucine; D014633:Valine
keywords: Anti-β(2)-glycoprotein antibodies; Antiphospholipid syndrome (APS); Calorimetry; PBMC proliferation; β(2)-glycoprotein-I (β(2)GP-I)