Fred V. Plapp

Monoclonal B‐cell lymphocytosis in blood donors

Monoclonal B‐cell populations have been detected in the peripheral blood of apparently healthy individuals by flow cytometry. In 2005, the term monoclonal B‐cell lymphocytosis (MBL) was proposed to describe these findings. MBL may be immunophenotypically similar to chronic lymphocytic leukaemia (CLL) and, like CLL, the prevalence is higher in males and older individuals. We studied the prevalence of MBL in blood donors from the Midwestern United States. Samples from 5141 donors were examined and seven (0·14%) were found to have immunophenotypic characteristics of MBL or CLL. Immunoglobulin heavy chain analysis yielded monoclonality or oligoclonality. Prior and subsequent to the study, an additional undetermined number of blood donors were screened and seven of these expressed immunophenotypic characteristics of MBL or CLL. We thus found a total of 14 healthy blood donors with monoclonal expansions of B‐lymphocyte populations. Of these, 12 were presumptively classified as MBL and two as CLL. All but two of the donors were male; the mean age was 59 years. The clinical importance of these findings with regard to transfusion medicine has not been established.

Immature platelet fraction as a predictor of platelet recovery following hematopoietic progenitor cell transplantation.

The immature platelet fraction (IPF) as determined by the Sysmex XE-2100 is a rapid automated measure of the least mature component of the platelet population and is thought to correlate with thrombopoietic activity of the marrow. We investigated the ability of IPF to predict platelet recovery following hematopoietic progenitor cell (HPC) transplantation. IPF was compared to standard parameters of hematopoietic recovery, including the immature reticulocyte fraction (IRF), an early predictor of recovery. Fifty patients undergoing peripheral blood HPC transplantation (38 autologous and 12 allogeneic) were followed daily for 11 to 28 days after transplantation with measurement of IPF, IRF, absolute neutrophil counts (ANC) and platelet counts. Mean days to recovery for IPF was 3.1 days less than for platelet count (P <.0001), 3.8 days less than for ANC (P <.0001), and 0.6 days less than for IRF (P = .0477). IPF recovered at least 1 day prior to platelet count in 79% (38 of 48) of patients, and was followed by platelet count recovery within 1 to 12 days (mean, 4.1 days). When autologous and allogeneic patient groups were analyzed separately, IPF recovered significantly earlier than platelet count and ANC in both groups (P <.0001). Thrombopoietin (TPO) levels in 5 patients receiving transplants correlated with IPF; however, this appeared to be secondary to an inverse correlation of both TPO and IPF with platelet count. IPF is comparable to IRF as one of the earliest predictors of hematopoietic recovery following peripheral blood HPC transplantation. IPF could potentially be useful as a predictor of platelet recovery in other bone marrow failure syndromes.

A solid‐phase antiglobulin test

A solid‐phase antiglobulin test was developed as an alternative to hemagglutination for compatibility testing. The solid‐phase endpoint of red cell adherence allowed results to be read visually or spectrophotometrically. This method was easier to perform than a hemagglutination antiglobulin test and had increased sensitivity without loss of specificity.

Solid‐phase ABO grouping and Rh typing

A solid‐phase adherence method (SPAM) for ABO grouping and Rh typing of red cells (RBCs) has been developed. Adherence reactions were read spectrophotometrically and interpreted by a computer. The SPAM had a 99.6 percent correlation with conventional microplate agglutination methods for ABO grouping and Rh typing. The increased sensitivity of the SPAM was demonstrated because it directly detected Du‐positive RBCs and weak subgroups of A and B.

The Role of Membrane Phospholipid in Expression of Erythrocyte Rh0(D) Antigen Activity

Abstract Previous investigators have reported that the expression of Rho(D) antigen activity by human erythrocytes and their membranes depended on the presence of phospholipid. In order to further elucidate the role of phospholipids in expression of Rho(D) antigen activity, erythrocyte membranes and partially purified Rho(D) antigens were incubated with bee venom phospholipase A2. Treatment of erythrocyte membranes with phospholipase A2 resulted in loss of Rho(D) antigen activity as detected by hemagglutination inhibition assays. However, subsequent solubilization of these treated membranes with deoxycholate allowed recovery of Rho(D) antigen activity. Phospholipase treatment of solubilized Rho(D) antigens, which had been partially purified by affinity chromatography on anti-Rho(D) IgG agarose columns, did not destroy Rho(D) antigen activity. These results suggested that phospholipids did not affect the antigenic determinants of the Rho(D) antigen since solubilized, partially purified Rho(D) antigens retained their antigenicity following exposure to phospholipase. Phospholipids were presumably required for proper orientation of Rho(D) antigens within erythrocyte membranes since Rho(D) membranes lost their antigenicity following phospholipase treatment.

Identification of Rho(D) antigen in polyacrylamide gels by an enzyme-linked immunoassay.

Human erythrocyte membranes were solubilized in sodium dodecyl sulfate at 100 degree C and subjected to polyacrylamide gel electrophoresis. The gels were sliced into segments and each segment was incubated with anti-Rho(D) IgG, washed, and then incubated with goat anti-human IgG covalently linked to alkaline phosphatase. Para-nitrophenyl phosphate was added to each slice and the absorbance of the solution surrounding each slice was measured at 405 nm. This technique demonstrated that the Rho (D) antigen is a protein with a mol, wt between 13, 000 and 30,000. This method should be applicable to the investigation of other membrane-bound antigens.

Factor V and VIII deficiency treated with therapeutic plasma exchange prior to redo mitral valve replacement.

A 33‐year‐old male was admitted to the hospital for a repeat mitral valve replacement. The original surgery, performed in India in 2008 due to rheumatic heart disease, required massive amounts of plasma replacement during and after the surgery. The patient was admitted to our hospital with extremely low Factor V and Factor VIII activities due to a rare combined Factor V and Factor VIII deficiency. His clinical condition on admission was grave due to severe pulmonary hypertension. It was decided to replace the patients Factor V using therapeutic plasma exchange (TPE) with fresh frozen plasma (FFP) just prior to surgery, and his Factor VIII with Factor VIII concentrate. The patient tolerated the valve replacement surgery very well, without excessive bleeding, and received several more TPE procedures postoperatively. He was successfully made replete with both coagulation factors with little to no bleeding during the procedure and postoperatively. TPE is a promising modality for the treatment of patients with similar factor deficiencies for which a specific factor concentrate is not available, especially those at risk of fluid overload from plasma transfusion. J. Clin. Apheresis 32:196–199, 2017.