Donor specific anti-HLA antibodies in hematopoietic stem cell transplantation. Single Center prospective evaluation and desensitization strategies employed.

BACKGROUND: In the setting of mismatched-hematopoietic stem cells transplantation, the detection of antibodies directed against donor-specific HLA allele(s) or antigen(s) (DSA) represents a barrier for engraftment. It is thus necessary to plan an immunosuppressive strategy, or to select an alternative donor. This prospective study aimed at evaluating the efficacy of our strategy for testing DSAs and the efficacy of the desensitization strategy (DS) employed between November 2017 and November 2020. MATERIALS AND METHODS: The anti-HLA antibody search was performed using the Luminex bead assays (Lifecode ID and LSA I/II-Immucor) and expressed as mean fluorescence intensity (MFI >1,000 positive). If the patient had DSAs and no alternative donors, a DS was employed with rituximab (day -15), 2 single volume plasmaphereses (PP; days -9 and -8), intravenous immunoglobulins (day -7) and infusion of HLA selected platelets, if persistent DSAs were directed against class I HLA. DS was scheduled with or without PP, according to the DSA MFI (>1,000 or <5,000) and FCXM (flow cytometry crossmatch). RESULTS: Twenty-two out of 126 patients (17.46%) showed anti-HLA antibodies, 5 of them DSAs (3.97% of total); 3 patients underwent DS obtaining engraftment. Female gender (p=0.033) and a history of previous pregnancies or miscarriages (p=0.009) showed a statistically significant impact on alloimmunization. Factors associated with a delayed neutrophil engraftment were patient's female gender (p=0.039), stem cell source (p=0.025), and a high HSCT-specific comorbidity index (p=0.028). None of the analyzed variables, including the DSA detection, influenced engraftment. CONCLUSIONS: Our study confirms the importance to test DSAs in mismatched-hematopoietic stem cells transplantation The DS used proved successful in removing DSAs. Prospective multicenter studies are needed to better define and validate consensus strategies on DSA management in HSCT.

Donating umbilical cord blood to a public bank or storing it in a private bank: knowledge and preference of blood donors and of pregnant women.

BACKGROUND: Umbilical cord blood (UCB) is a source of stem cells for allogeneic haematopoietic transplantation in paediatric and adult patients with haematological malignancies and other indications. Voluntary donation is the basis for the success of unrelated UCB transplantation programmes. In the last few years a growing number of private banks offer their services to expectant parents, to store UCB for future use. The debate concerning UCB donation and private preservation has been ongoing for several years. The aims of this single centre study were to explore knowledge about UCB stem cells and attitudes towards voluntary UCB donation or private UCB preservation among both blood donors and pregnant women. MATERIALS AND METHODS: This study was conducted at the "Sapienza" University of Rome. Two types of anonymous questionnaires were prepared: one type was administered to 1,000 blood donors while the other type was distributed to 300 pregnant women. RESULTS: Most blood donors as well as the majority of pregnant women had some general knowledge about UCB (89% and 93%, respectively) and were aware of the possibility of donating it (82% and 95%). However, the level of knowledge regarding current therapeutic use resulted generally low, only 91 (10%) among informed blood donors and 69 (31%) among informed pregnant women gave a correct answer. The survey revealed a preference for voluntary donation both among blood donors (76%) and among pregnant woman (55%). Indeed, a minority of blood donors (6.5%) and of pregnant women (9%) would opt to store UCB for private use. DISCUSSION: The study raises the following considerations: (i) the large support for UCB donation expressed by blood donors and by pregnant women suggests that UCB preservation does not represent an obstacle to the expansion of UCB donation and to development of unrelated transplantation programmes; (ii) information about UCB donation and preservation should be carefully given by professionals and institutions.

Histopathological and molecular features of persistent polyclonal B-cell lymphocytosis (PPBL) with progressive splenomegaly.

Five cases of persistent polyclonal B-cell lymphocytosis (PPBL) with progressive splenomegaly are reported; three were splenectomized. BCL2/IGH rearrangements were found in three cases; HLA-DRB1*07 in all. Bone marrow (BM) trephines showed a moderate lymphoid infiltrate with intrasinusoidal distribution resembling a splenic marginal-zone lymphoma. Splenic white pulp revealed an enlargement of the marginal-zone area; red pulp was infiltrated by the same lymphocytes engulfing the sinuses. Splenic and BM B-lymphocytes were CD79a(+)/CD20(+)/IgM(+)/IgD(+)/bcl-2(+)/CD27(+)/DBA.44(-)/CD31(-) and polyclonal by immunophenotype/polymerase chain reaction. PPBL features an expansion of splenic marginal-zone B-lymphocytes, which infiltrate BM sinusoids and circulate in the blood with no evidence of clonality, even in cases with progressive splenomegaly.