Immunoglobulin G and phosphatidylserine in regenerative and nonregenerative immune‐mediated anemias of dogs (original) (raw)

2021, Journal of Veterinary Internal Medicine

Background: Although precursor-targeted immune-mediated anemia (PIMA) is thought to be caused by immune targeting of erythroid precursors (nucleated RBCs, nRBCs), its pathogenesis is unknown. Immunoglobulin G (IgG) or phosphatidylserine (PS) may promote nRBC destruction in PIMA. Hypothesis: Dogs with PIMA have increased nRBC IgG and PS, and dogs with immune-mediated hemolytic anemia (IMHA) have increased RBC PS compared to healthy dogs. Animals: Blood from 20 healthy dogs and from dogs with IMHA (11) or other (non-IMHA) conditions (9), and marrow aspirates with or without blood from 10 healthy dogs and from dogs with PIMA (17) or other (non-IMHA, non-PIMA) conditions (7). Methods: Marrow nRBC stages were separated by density gradient. Flow cytometry was used to assess the percentage of RBCs or nRBCs with increased IgG or PS. Results: Red blood cell (RBC) IgG positivity was increased in 9/11 IMHA dogs and 0/9 non-IMHA dogs. Red blood cell PS positivity was increased in 10/11 IMHA dogs and 2/9 non-IMHA dogs. Five of 17 PIMA dogs had increased nRBC IgG positivity in midor late-stage fractions, whereas all 7 non-PIMA dogs were negative. Mid-and latestage erythroid precursor PS was significantly higher in PIMA dogs compared to healthy dogs. Five of 14 PIMA dogs had increased RBC IgG positivity. Conclusions: Immunoglobulin G and PS may promote destruction of nRBCs in PIMA dogs; PS may promote destruction of RBCs in IMHA dogs. K E Y W O R D S bone marrow, erythroid maturation arrest, flow cytometry, immune-mediated hemolytic anemia, ineffective erythropoiesis, precursor-targeted immune-mediated anemia Abbreviations: AnV-Ca, annexin buffer with CaCl 2 ; AnV-Ca-free, annexin buffer without CaCl 2 ; BSA, bovine serum albumin; C3, complement protein 3; DEA, dog erythrocyte antigen; Hct, hematocrit; HEPES, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer; IgA, immunoglobulin A; IgG, immunoglobulin G; IgM, immunoglobulin M; IMHA, immune-mediated hemolytic anemia; IMN, immune-mediated neutropenia; IMT, immune-mediated thrombocytopenia; nRBC, nucleated red blood cell (erythroid precursor); PIMA, precursor-targeted immune-mediated anemia; PS, phosphatidylserine; RBC, red blood cell.