Biomedical subjects

Virginie Ferrera

Publications and source records attributed to Virginie Ferrera.

3 recordsLinked to original sources

PubMed2006

HLA-DRB1 polymorphism is associated with Kell immunisation.

K immunisation is observed in some polytransfused patients and pregnant women but does not occur in all cases of K incompatibility. This study analysed the role of genetic background in this selective response to K antigen by investigating HLA-DRB1 alleles associated with K immunisation in a southern European population. HLA-DRB1 genotyping was performed by polymerase chain reaction sequence-specific oligonucleotide/sequence-specific primer procedures in 54 K immunised patients and 200 healthy controls. The frequency of HLA-DRB1*11 was significantly higher in K immunised patients than healthy controls: 31 of 54 (57%) vs. 56 of 200 (28%) (P(c) < 0.001). In the remaining K immunised HLA-DRB1*11-negative patients, the frequency of HLA-DRB1*13 was increased: 14 of 23 (61%) vs. 49 of 144 in healthy controls (34%) (P < 0.02). The combined frequency of the two HLA-DRB1 alleles (HLA-DRB1*11 and HLA-DRB1*13) was 83% in K immunised patients when compared with 52% in healthy controls (P(c) < 0.001). K and k differ by a single amino acid T193 (M). The DRB1*11 and DRB1*13 alleles share a HLA-DRB1 gene sequence containing S in position 13, D in 70 and A in 74, and coding for the P4 pocket within the HLA-DR binding groove. This feature of the HLA-DRB1 gene could be involved in the K peptide presentation through a polymorphism ligand specific for the T193 (M) of K. In conclusion, this study demonstrated a high frequency of HLA-DRB1*11 or HLA-DRB1*13 alleles in K immunised patients, which could be due to specific K peptide presentation by HLA-DR molecules.

Alleles↗

PubMed2005

HLA-DRB1 alleles and Jk(a) immunization.

BACKGROUND: In transfusion medicine, anti-Jk(a) has been implicated in hemolytic transfusion reactions. Development of anti-Jk(a) after transfusion does not always occur after Jk(a-) patients receive at least 1 unit of Jk(a+) blood unit. This study was designed to identify HLA-DRB1 alleles associated with predisposition to Jk(a) immunization after blood transfusion or pregnancy. STUDY DESIGN AND METHODS: Genotyping by polymerase chain reaction and sequence-specific oligonucleotide probe nonradioactive hybridization/sequence-specific primers was performed in 20 Jk(a)-immunized patients and 200 controls from the same southern European population. RESULTS: Genotyping showed that HLA-DRB1*01 was significantly more frequent in Jk(a)-immunized patients than controls: 55 percent versus 17 percent (odds ratio [OR], 5.9; confidence interval [CI], 2.3-15.5; corrected p value<0.05). Because HLA-DRB1*0101, DRB1*0102, and DRB1*1001 share a common sequence in their B1 chain, that is, F in 13, R in 71, and A in 74, HLA genetic predisposition was analyzed by comparing patients and controls with respect to the distribution of F13/R71/A74-positive and -negative alleles. Results demonstrated greater positivity of the F13/R71/A74 sequence (DRB1*0101, *0102, or *1001) in patients than in controls: 65 percent versus 19.5 percent (OR, 7.7; CI, 2.9-20.5; p<0.001). CONCLUSION: In conclusion, HLA-DRB1*0101, DRB1*0102, and DRB1*1001, which share a common DRB1 sequence, appeared to be overrepresented in Jk(a)-immunized patients.

Alleles↗

PubMed2003

Adsorption of autoantibodies in the presence of LISS to detect alloantibodies underlying warm autoantibodies.

BACKGROUND: The safe transfusion of patients with warm autoimmune hemolytic anemia requires an efficient and time-saving assay to detect alloantibodies underlying autoantibodies. Methods used include RBCs treated with ZZAP reagent, proteolytic enzyme, or untreated RBCs in the presence of PEG. We propose a method using LISS, which presents some advantages over previous methods. STUDY DESIGN AND METHODS: We evaluated the effectiveness of autoantibody adsorption with papain-treated and untreated RBCs in the presence of LISS for removal of autoantibodies, without affecting alloantibodies. RESULTS: One-hundred twenty sera containing autoantibodies were adsorbed with our routine method, which uses papain-treated allogeneic RBCs. Seven-hundred twenty adsorptions (mean, 6 per sample) and 21,600 minutes (mean, 180 min per sample) were required to remove autoantibodies. Fifty sera were adsorbed with our routine method that uses papain-treated allogeneic RBCs in the presence of LISS. The number of adsorptions and the completion time were, respectively, 144 (mean, 2.9 per sample) and 2,880 minutes (mean, 57.6 min per sample). Twenty sera were evaluated with untreated autologous RBCs, in the presence of LISS; 58 adsorptions (mean, 2.9) and 1,160 minutes (mean, 58 min per sample) were required. Three adsorptions with antigen-negative allogeneic RBCs were performed on 8 sera containing alloantibodies with weak reactivity (anti-K [1], anti-D [1], anti-Fya[2], anti-S [2], anti-E [1], and anti-Jka[1]). Alloantibodies were detected with the LISS procedure with papain-treated and untreated RBCs and the routine papain method. Alloantibodies with weak reactivity, tested against the same antibody-detection RBCs, remained unchanged following adsorption of 5 sera. An anti-S, with very weak reactivity, was no longer detected, and an anti-Jka became weaker (1+), regardless of the procedure used. One anti-D became weaker only with the LISS adsorption method. CONCLUSION: Autoantibodies can be adsorbed more efficiently in the presence of LISS.

Autoantibodies↗