An immunogenomic exome landscape of triple positive primary antiphospholipid patients.

Primary antiphospholipid syndrome is characterized by thrombosis and autoantibodies directed against phospholipids or associated proteins. The genetic etiology of PAPS remains unknown. We enrolled 21 patients with thromboembolic events associated to lupus anticoagulant, anticardiolipin and anti β2 glycoprotein1 autoantibodies.

Comparison of two peripheral mononuclear cell isolation protocols for flow cytometry crossmatching.

In clinical organ transplantation, flow cytometry crossmatching can be performed on total blood with a hemolysis step or after a preliminary mononuclear cell separation step using a standard Ficoll-Hypaque protocol. Here, we compared the Ficoll-Hypaque step with a faster technique for isolating mononuclear cells (the SepMate tube), using the same samples (collected and stored at room temperature for 0, 24, 48 or 72 hours). We found that the SepMate separation protocol is easily applied to flow cytometry crossmatching (with or without pronase treatment), provided that the samples have been stored at room temperature for 48 hours or less.

Pronase treatment improves flow cytometry crossmatching results.

Flow cytometry crossmatching (FC-XM) is the most sensitive cell-based method for detecting donor-specific antibodies in clinical organ transplantation. Unfortunately, background FC-XM reactivity is elevated in assays with B lymphocytes-partly because of nonspecific immunoglobulin binding by Fc receptors and B-cell surface immunoglobulins. To reduce the background reactivity in a B-cell FC-XM assay, we treated lymphocytes with pronase (1 mg/mL for 30 minutes).

Unexpected Positive Prospective Crossmatches in Organ Transplant.

Preformed donor-specific antibodies against human leukocyte antigen can induce antibody-mediated rejection after organ transplant. Hence, future transplant recipients undergo pretransplant screening for preformed antibodies (ie, virtual crossmatch). Subsequently, prospective (analytic) crossmatching is performed using conventional, complement-dependent cytotoxicity assays and/or flow cytometry-based methods.

False Positive B-Cells Crossmatch after Prior Rituximab Exposure of the Kidney Donor.

Crossmatching is essential prior to kidney transplantation to confirm compatibility between the donor and the recipient, particularly to prevent acute antibody-mediated rejection. An unexpected positive crossmatch may be obtained in recipients with an autoimmune disease or preexisting antibodies not detected by single-antigen bead array due to complement interference or who have been previously treated by desensitization protocols such as rituximab, antithymocyte globulin, or intravenous immunoglobulins. We report donor and recipient investigations that revealed unexpected positive B-cells crossmatch, probably due to donor cells, as the donor had received rituximab therapy shortly before organ harvesting, in a context of severe idiopathic thrombocytopenic purpura.