Elevated numbers of PD-L1 expressing B cells are associated with the development of AIDS-NHL.

The risk for non-Hodgkin lymphoma (NHL) is markedly increased in persons living with human immunodeficiency virus (HIV) infection, and remains elevated in those on anti-retroviral therapy (cART). Both the loss of immunoregulation of Epstein-Barr virus (EBV) infected cells, as well as chronic B-cell activation, are believed to contribute to the genesis of AIDS-related NHL (AIDS-NHL). However, the mechanisms that lead to AIDS-NHL have not been completely defined. A subset of B cells that is characterized by the secretion of IL10, as well as the expression of the programmed cell death ligand-1 (PD-L1/CD274), was recently described. These PD-L1+ B cells can exert regulatory function, including the dampening of T-cell activation, by interacting with the program cell death protein (PD1) on target cells. The role of PD-L1+ B cells in the development of AIDS-NHL has not been explored. We assessed B cell PD-L1 expression on B cells preceding AIDS-NHL diagnosis in a nested case-control study of HIV+ subjects who went on to develop AIDS-NHL, as well as HIV+ subjects who did not, using multi-color flow cytometry. Archival frozen viable PBMC were obtained from the UCLA Multicenter AIDS Cohort Study (MACS). It was seen that the number of CD19+CD24++CD38++and CD19+PD-L1+cells was significantly elevated in cases 1-4 years prior to AIDS-NHL diagnosis, compared to controls, raising the possibility that these cells may play a role in the etiology of AIDS-NHL. Interestingly, most PD-L1+ expression on CD19+ cells was seen on CD19+CD24++CD38++ cells. In addition, we showed that HIV can directly induce PD-L1 expression on B cells through interaction of virion-associated CD40L with CD40 on B cells

Author Correction: Elevated numbers of PD-L1 expressing B cells are associated with the development of AIDS-NHL.

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Lethal iron deprivation induced by non-neutralizing antibodies targeting transferrin receptor 1 in malignant B cells

A number of antibodies have been developed that induce lethal iron deprivation (LID) by targeting the transferrin receptor 1 (TfR1/CD71) and either neutralizing transferrin (Tf) binding, blocking internalization of the receptor and/or inducing its degradation. We have developed recombinant antibodies targeting human TfR1 (ch128.1 and ch128.1Av), which induce receptor degradation and are cytotoxic to certain malignant B-cells. We now show that internalization of TfR1 bound to these antibodies can lead to its sequestration and degradation, as well as reduced Tf uptake, and the induction of a transcriptional response consistent with iron deprivation, which is mediated in part by downstream targets of p53. Cells resistant to these antibodies do not sequester and degrade TfR1 after internalization of the antibody/receptor complex, and accordingly maintain their ability to internalize Tf. These findings are expected to facilitate the rational design and clinical use of therapeutic agents targeting iron import via TfR1 in hematopoietic malignancies.Fil: Rodríguez, José A.. University of California at Los Angeles; Estados UnidosFil: Luria Pérez, Rosendo. University of California at Los Angeles; Estados Unidos. Hospital infantil de México “Federico Gómez”; MéxicoFil: López Valdés, Héctor E.. University of California at Los Angeles; Estados UnidosFil: Casero, David. University of California at Los Angeles; Estados UnidosFil: Daniels, Tracy R.. University of California at Los Angeles; Estados UnidosFil: Patel, Shabnum. University of California at Los Angeles; Estados UnidosFil: Avila, David. University of California at Los Angeles; Estados UnidosFil: Leuchter, Richard. University of California at Los Angeles; Estados UnidosFil: So, Sokuntheavy. University of California at Los Angeles; Estados UnidosFil: Ortiz Sánchez, Elizabeth. University of California at Los Angeles; Estados UnidosFil: Bonavida, Benjamin. University of California at Los Angeles; Estados UnidosFil: Martínez Maza, Otoniel. University of California at Los Angeles; Estados UnidosFil: Charles, Andrew C.. University of California at Los Angeles; Estados UnidosFil: Pellegrini, Matteo. University of California at Los Angeles; Estados UnidosFil: Helguera, Gustavo Fernando. University of California at Los Angeles; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Penichet, Manuel L.. University of California at Los Angeles; Estados Unido

Altered Host Immunity, Human T Lymphotropic Virus Type I Replication, and Risk of Adult T-Cell Leukemia/Lymphoma: A Prospective Analysis from the ATL Cohort Consortium

Background: Adult T-cell leukemia/lymphoma (ATL) is a rare and often fatal outcome of infection with human T-lymphotropic virus type I (HTLV-I). Altered host immunity in HTLV-I carriers has been postulated as a risk factor for ATL, but is not well understood. Methods: We prospectively examined well-validated serologic markers of HTLV-I pathogenesis and host immunity in 53 incident ATL cases and 150 carefully matched asymptomatic HTLV-I carriers from eight population-based studies in Japan, Jamaica, the United States and Brazil. We used multivariable conditional logistic regression, conditioned on the matching factors (cohort/race, age, sex, and sample collection year), to evaluate the biomarkers’ associations with ATL in all subjects and by years (≤5, >5) from blood draw to ATL diagnosis. Results: In the pooled population, above-median soluble interleukin-2-receptor-alpha levels (sIL2R, v. ≤ median; odds ratio (OR), 95% confidence interval (CI)=4.08, 1.47-11.29) and anti-Tax seropositivity (anti-Tax; OR, 95% CI=2.97, 1.15-7.67), which indicate T cell activation and HTLV-I replication, respectively, were independently associated with an increased ATL risk. Above-median total immunoglobulin E levels (v. ≤ median; OR, 95% CI=0.45, 0.19-1.06), which indicate type 2 (B cell) activation, predicted a lower ATL risk. The sIL2R and anti-Tax associations with ATL were stronger in samples collected ≤5 years pre-diagnosis. Conclusions: The biomarker profile predictive of ATL risk suggests a role for heightened T cell activation and HTLV-I replication and diminished type 2 immunity in the etiology of ATL in HTLV-I carriers. Translation of these findings to clinical risk prediction or early ATL detection requires further investigation. Acknowledgements: This abstract is presented on behalf of the ATL Cohort Consortium