Anti-Blood Group Antibodies in Intravenous Immunoglobulin May Complicate Interpretation of Antibody Titers in ABO-Incompatible Transplantation.

Patients receiving ABO-incompatible (ABOi) kidney transplants are treated before and after transplant with combination therapy, such as intravenous immunoglobulin (IVIG) and therapeutic plasma exchange, to prevent allograft rejection by reducing anti-A and anti-B titers. Although generally considered safe, it is well known that commercial IVIG products contain detectable anti-A and anti-B, which can be associated with hemolysis. Different preparative manufacturing techniques during the production of IVIG affect ABO antibody levels in IVIG preparations; therefore, some manufacturers now use new methods to reduce anti-A/B levels at the preproduction stage. The variations in implementing these strategies creates the potential for significant variation in antibody titers between products and, in some cases, even between lots of the same IVIG product. We report a case of persistently elevated anti-A titers in an ABOi kidney transplant recipient associated with elevated ABO antibody titers present in the preparation of IVIG used at our facility.

Altered generation of induced regulatory T cells in the FVB.mdr1a-/- mouse model of colitis.

The FVB.mdr1a(-/-) mouse, lacking the small molecule pump P-glycoprotein (P-gp), is a commonly used model for the study of spontaneous T cell-mediated colitis. In addition, MDR1 polymorphisms and P-gp deficiency in humans have been linked to the development of ulcerative colitis. We now demonstrate that mice with P-gp deficiency have decreased levels of Foxp3(+) regulatory T cells (Tregs) in the intestinal lamina propria. This decrease is not due to either increased Treg apoptosis, altered Treg trafficking, or enhanced Treg plasticity to become Foxp3(+)IL-17(+) cells. Instead, P-gp deficiency appears to restrict the development of induced Treg cells (iTregs), as fewer Foxp3(+) iTregs developed from naive FVB.mdr1a(-/-) T cells both upon transforming growth factor-ß (TGF-ß) treatment in vitro and after adoptive transfer into FVB.rag2(-/-) recipients. Rather, in vitro TGF-ß treatment results in a IL-17(+)CD4(+) T cell. This failure of iTregs to develop explains the decrease in Foxp3(+) Tregs in the FVB.mdr1a(-/-) intestine, representing a need to investigate this novel disease mechanism in human inflammatory bowel disease patients with MDR1 polymorphisms.