title: Prevalence of antibodies to a new histo-blood system: the FORS system.
abstract: In 1987, three unrelated English families were reported with a putative blood subgroup called Apae. Swedish researchers later found evidence leading to abolishment of the Apaesubgroup and establishment instead of the FORS blood group system (System 31 - ISBT, 2012). It is important to know the prevalence of antibodies in order to make the best decisions in transfusion medicine. Cells expressing the Forssman saccharide, such as sheep erythrocytes, are needed to detect the anti-Forssman antibody. The aim of this study was to define the prevalence of human anti-Forssman antibody.
  
  
  
  Plasma samples from 800 individuals were studied. Sheep erythrocytes or Forssman "kodecytes" were mixed with the plasma samples using the tube technique. Plasma from an Apaeindividual was used as a negative control and monoclonal anti-Forssman antibody (M1/22.25.8HL cell line supernatant) was used as the positive control.
  
  
  
  Of the 800 individuals tested, one was negative for the presence of anti-Forssman antibody. We compared the anti-Forssman antibody reaction pattern between genders and found that males have weaker reactions than females, both at room temperature (p=0.026) and at 37 °C (p=0.043). We also investigated the reaction pattern of anti-Forssman antibody in relation to ABO and Rh blood group types without finding any significant differences.
  
  
  
  Sheep erythrocytes are suitable for searching for human anti-Forssman antibody. The quantity of anti-Forssman antibodies in plasma is higher in females than in males. In the population (n=800) studied here, we found one individual lacking the anti-Forssman antibody. These results contribute to the data already published, confirming that FORS is a rare blood group.
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Jesus
authors.affiliation: Department for Clinical Chemistry and Transfusion Medicine, Institute for Biomedicine, Sahlgrenska Academy, University of Gothenburg, Sweden.
authors.forename: Camilla
authors.initials: C
authors.lastname: Hesse
authors.affiliation: Polytechnic Institute of Coimbra, ESTESC-Coimbra Health School, Department Complementary Sciences, Coimbra, Portugal.|INESC Coimbra, Coimbra, Portugal.
authors.forename: Clara
authors.initials: C
authors.lastname: Rocha
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.
authors.forename: Nádia
authors.initials: N
authors.lastname: Osório
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Valado
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.|I&D Unit "Química-Física Molecular", Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal.
authors.forename: Armando
authors.initials: A
authors.lastname: Caseiro
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Gabriel
authors.affiliation: Department for Clinical Chemistry and Transfusion Medicine, Institute for Biomedicine, Sahlgrenska Academy, University of Gothenburg, Sweden.
authors.forename: Lola
authors.initials: L
authors.lastname: Svensson
authors.affiliation: Department of Pathology, Institute for Biomedicine, Sahlgrenska Academy, University of Gothenburg, Sweden.
authors.forename: Ali-Reza
authors.initials: AR
authors.lastname: Moslemi
authors.affiliation: Department of Medical Laboratory Sciences, Faculty of Health Professions, Al-Quds University, East Jerusalem, Palestine.
authors.forename: Wafa Abu
authors.initials: WA
authors.lastname: Siba
authors.affiliation: Department of Medical Laboratory Sciences, Faculty of Health Professions, Al-Quds University, East Jerusalem, Palestine.
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: Srour
authors.affiliation: Blood and Transfusion Medicine Department, Coimbra Hospital and University Centre (CHUC), Coimbra, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Pereira
authors.affiliation: Blood and Transfusion Medicine Department, Coimbra Hospital and University Centre (CHUC), Coimbra, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Tomaz
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.|Department of Anatomic Pathology, Coimbra Hospital and University Centre (CHUC), Coimbra, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Teixeira
authors.affiliation: Biomedical Sciences Department of ESTESC - Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra, Portugal.|Biophysics and Biomathematics Institute, IBILI-Faculty of Medicine, University of Coimbra, Coimbra, Portugal.|CIMAGO, FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal.|CNC.IBILI, University of Coimbra, Coimbra, Portugal.
authors.forename: Fernando
authors.initials: F
authors.lastname: Mendes
mesh_terms: D000818:Animals; D001789:Blood Group Antigens / Q000097:blood* / Q000276:immunology; D001788:Blood Grouping and Crossmatching / Q000379:methods*; D005260:Female; D005577:Forssman Antigen / Q000097:blood* / Q000276:immunology; D006801:Humans; D007518:Isoantibodies / Q000097:blood* / Q000276:immunology; D008297:Male; D009844:Oligosaccharides / Q000097:blood* / Q000276:immunology; D015995:Prevalence; D012756:Sheep
chemical_list: D001789:Blood Group Antigens; C402893:Forssman pentasaccharide; D007518:Isoantibodies; D009844:Oligosaccharides; D005577:Forssman Antigen