Polymorphism of the HLA system and weak antibody response to BNT162b2 mRNA vaccine.

The polymorphism of the HLA system has been extensively studied in COVID-19 infection, however there are no data about the role of HLA on vaccine response. We report here the HLA-A, -B, -C, and DRB1 allelic frequencies of n = 111 individuals after BNT162b2 mRNA vaccine, selected on the basis of lower antibody levels (<5% percentile) after the second dose among a total of n = 2569 vaccinees, and compare them with the frequencies of a reference population. We found that differences in the frequencies of the alleles HLA-A*03:01, A*33:03, B*58:01 and at least one haplotype (HLA-A*24:02~C*07:01~B*18:01~DRB1*11:04) are associated with a weaker antibody response after vaccination, together with the age of vaccinees. Our results might suggest a role played by some HLA alleles or haplotypes in antibody production after the BNT162b2 mRNA vaccine, giving insights into the tracking of potentially susceptible individuals across populations. Further studies are needed to better define our exploratory findings and dissect the role of HLA polymorphism on response to anti-COVID-19 vaccines.

Correlation analysis between virtual and Complement-Dependent-Cytotoxicity crossmatch in a monocenter retrospective series of 118 allografted patients.

PURPOSE OF THE STUDY: The detection of patients' anti-HLA antibodies before allogeneic hematopoietic stem cell transplantation (HSCT) may affect post-transplant outcome, due to a potential detrimental impact on engraftment or toxicity-related issues. Crossmatch (XM) techniques provide support to physicians during the pre-transplant phase but the role of Complement-Dependent Cytotoxicity XM (CDC-XM) is not well-defined when performed routinely and in parallel with the virtual XM. PATIENTS AND METHODS: We report here our experience with both virtual and CDC-XM tests on n = 118 patients undergoing search for a donor other than HLA-identical sibling from July 2013 to June 2018 at our Institution. When anti-HLA antibodies (Abs) were present, they were classified as donor-specific Abs (DSA) or non-DSA. RESULTS: On the n = 118 patients, n = 35 (29.7 %) had a positive virtual XM test (of which one of more DSA were found in n = 8; 6.8 %) and n = 5 had a positive CDC-XM test. These latter, positive for HLA class II only, were interpreted as false-positive results due to prior administration of anti-CD20 to the patients, all affected by lymphoma; none of them had a positive virtual XM for anti-HLA Abs of class II. Importantly, all these patients successfully engrafted, further supporting the lack of significant impact of CDC-XM positive results in this series. CONCLUSIONS: According to our data on more than a hundred patients, routinely performed CDC-XM does not seem to add significant information with respect to virtual XM. We cannot exclude the usefulness of CDC-XM in specific situations, although a positive CDC-XM result was an unfrequent event.

The number of HLA confirmatory tests during unrelated donor search as a driver for the evaluation of back-up haploidentical donor(s).

INTRODUCTION: the identification of a suitable donor in an appropriate timing represents a crucial step in the preparation of allogeneic stem cell transplantation (HSCT). At our Institution, for patients lacking an HLA-identical sibling, a haploidentical donor is considered in the absence of a 10/10-matched or a one-locus HLA-mismatched unrelated donor (UD), but the optimal timing of work-up of potential familiar haploidentical donor(s) by the Apheresis Team is actually unknown. PATIENTS & METHODS: we analyzed here n = 167 UD searches launched at our Hospital between July 2013 and July 2018 and looked for any correlation between the number of HLA confirmatory tests received and the final type of donor selected for HSCT, in an attempt to identify those situations where prompt evaluation of haploidentical donor(s) is warranted. RESULTS: a total of n = 117 transplants were performed and haploidentical HSCTs were n = 16 (14 %). In n = 93 cases (56 %) the number of HLA confirmatory tests received were two; they were one, zero and three for n = 52, n = 14 and n = 8 patients, respectively. Only 5 % of haploidentical donors were used when two confirmation test samples were received whereas this percentage rises to 17 % when only one sample reached the HLA lab. When no confirmation tests were available, haploidentical transplant occurred in 100 % of cases. CONCLUSIONS: besides the situations with no HLA confirmation tests, the evaluation of any haploidentical donor(s) should be promptly started also when only one HLA confirmatory test is received, in order to optimise the potential work-up process and avoid delay in transplantation.

The role of quantitative polymerase chain reaction in the management of follicular lymphoma patients.

AIMS AND BACKGROUND: In order to increase the prognostic significance of polymerase chain reaction (PCR) data it has been suggested that quantitative PCR can be used to measure tumor burden. However, this option has not yet been definitely supported or refuted in patients with follicular lymphoma (FL). We decided to evaluate whether knowledge of the quantitative level of minimal residual disease and its variations can be of use in the management of FL patients. METHODS: We used qualitative and competitive PCR to study 11 patients with refractory or relapsed FL harboring the t(14;18) translocation who underwent autologous (nine patients) or allogeneic (two patients) stem cell transplantation (SCT). Competitive PCR was performed with a multiple competitor carrying specific sequences including Bcl2/IgH MBR and mcr, and the beta-globin gene. RESULTS: After a median post-SCT follow-up of 44 months (range, 12-62), overall survival was 91% and disease-free survival 82%. The quantitative PCR data showed that: 1) effective chemotherapy before SCT substantially (1-2 log) reduced the tumor burden in the bone marrow (BM); 2) the increase in rearranged DNA detected in BM was associated with disease progression and relapse; 3) a PCR-negative autograft seemed to lead to lasting molecular remission even when it was performed in patients with a low level of BM infiltration before transplant; and 4) allo-SCT made and maintained the BM PCR negative even in the presence of a greater tumor burden before SCT. Six of the nine patients having CR after SCT (four auto and two allo) are in continuous molecular remission. CONCLUSIONS: In FL patients qualitative and quantitative PCR may provide data that can be helpful for the prognostic evaluation of tumor progression and the early detection of impending relapse by highlighting biological features such as the quality of the infused material, the tumor burden at transplant, and the behavior of tumor cells after transplant.

Chronic myelogenous leukemia with acquired c-kit activating mutation and transient bone marrow mastocytosis.

Mutations of the c-kit gene have been reported in myeloproliferative disorders. We describe here a case of Ph+ (b2a2) chronic myelogenous leukemia that, during the course of disease, showed an unusual bone marrow mast-cell infiltration. A mutational screening for the c-kit gene, performed on DNA routinely cryopreserved during the follow-up, evidenced the D816Y-activating mutation as an additional genetic abnormality. Treatment with imatinib mesylate resulted in a substantial decrease of the BCR-ABL/ABL ratio and in the absence of c-kit mutation. It is likely that the superimposed c-kit mutation, in this case, may account for the transient bone marrow mastocytosis.

The expression of the non-receptor tyrosine kinases Arg and c-abl is differently modulated in B lymphoid cells at different stages of differentiation.

The products of the human ARG gene and the human ABL gene characterize the Abelson family of non-receptor tyrosine protein kinases. Both genes are ubiquitously expressed. The interactions of these two similar protein kinases are still not well known, although it has been suggested that they could cooperate, with redundant actions, to provide intracellular signals in the cells. Lymphopenia occurs in mice with homozygous disruption of c-abl, indicating that in certain tissues Arg is unable to substitute c-abl functions. In B and T lymphoid cell lines at different stages of differentiation, we studied, by a reverse transcriptase-competitive polymerase chain reaction and Western blotting, Arg and c-abl in order to evaluate whether the expression pattern of the two genes could give insight as to why they do not exhibit overlapping roles in lymphocytes and whether the product levels of the two genes are related to lymphoid differentiation. The data showed that their expression is differently modified in lymphoid B cell lines. The highest Arg transcript and protein levels are in the mature B cells.