COVID-19 vaccinated children, adolescents, and young adults with acute lymphoblastic leukemia show spike reactive antibodies and multifunctional T-cells.

Little is known about the efficacy of COVID-19 vaccines during acute lymphoblastic leukemia therapy (ALL); data for COVID-19 vaccine immune responses in pediatric leukemia remain sparse. We conducted a single center study of patients aged 5-25 years undergoing ALL chemotherapy who received COVID-19 vaccination. Twenty-one patients were enrolled; efficacy was evaluable in 20. Twenty were vaccinated while receiving chemotherapy. Twenty received the BNT162b2 mRNA vaccine. Spike reactive antibodies (S-IgG) and/or T-cells (SRT) were detected in 16 of 20 (80%) vaccinated patients; 13 (65%) and 9 (45%) were positive for S-IgG and SRT, respectively. Six (30%) showed both spike reactive B and T-cell responses. Eleven of the 13 with S-IgG positivity were negative for anti-Nucleocapsid IgG, an antibody profile consistent with a vaccine induced immune response. All 13S-IgG+ patients showed neutralizing antibodies. SRT included CD4+ (7) and CD8+ (6) T-cells; both CD4+ and CD8+ SRT were seen in 4. SRT were multifunctional (producing multiple cytokines) in most patients (8 of 9); 4 showed SRT with triple cytokine and B-cell co-stimulatory responses, indicating a multimodal adaptive immune response. Immune responses were seen among patients vaccinated in the settings of lymphopenia (6 of 12) intensive chemotherapy (3 of 4), and Peg allergy (6 of 8). Sequencing revealed public CD4+ and CD8+ TCR sequences reactive to epitopes across the spike protein. In conclusion, COVID-19 vaccination induced B and/or T-cell responses in a majority of children and young adults undergoing ALL chemotherapy.

Membrane-bound TRAIL supplements natural killer cell cytotoxicity against neuroblastoma cells.

Neuroblastoma cells have been reported to be resistant to death induced by soluble, recombinant forms of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) (CD253/TNFSF10) because of low or absent expression of caspase-8 and/or TRAIL-receptor 2 (TRAIL-R2/DR5/CD262/TNFRSF10b). However, their sensitivity to membrane-bound TRAIL on natural killer (NK) cells is not known. Comparing microarray gene expression and response to NK cell-mediated cytotoxicity, we observed a correlation between TRAIL-R2 expression and the sensitivity of 14 neuroblastoma cell lines to the cytotoxicity of NK cells activated with interleukin (IL)-2 plus IL-15. Even though most NK cytotoxicity was dependent upon perforin, the cytotoxicity was supplemented by TRAIL in 14 of 17 (82%) neuroblastoma cell lines as demonstrated using an anti-TRAIL neutralizing antibody. Similarly, a recently developed NK cell expansion system employing IL-2 plus lethally irradiated K562 feeder cells constitutively expressing membrane-bound IL-21 (K562 clone 9.mbIL21) resulted in activated NK cells derived from normal healthy donors and neuroblastoma patients that also utilized TRAIL to supplement cytotoxicity. Exogenous interferon-γ upregulated expression of caspase-8 in 3 of 4 neuroblastoma cell lines and increased the contribution of TRAIL to NK cytotoxicity against 2 of the 3 lines; however, relatively little inhibition of cytotoxicity was observed when activated NK cells were treated with an anti-interferon-γ neutralizing antibody. Constraining the binding of anti-TRAIL neutralizing antibody to membrane-bound TRAIL but not soluble TRAIL indicated that membrane-bound TRAIL alone was responsible for essentially all of the supplemental cytotoxicity. Together, these findings support a role for membrane-bound TRAIL in the cytotoxicity of NK cells against neuroblastoma cells.

Truncated Bcl-2, a potential pre-metastatic marker in prostate cancer.

A novel truncated form of Bcl-2, termed Bcl-2psi, was discovered in invasive prostate cancer cells, using laser capture microdissection, RNA-polymerase cycling reaction, and microarray analysis. The expression of Bcl-2psi increased prior to metastasis in higher-grade prostate cancer. The immunoreactive Bcl-2psi was specifically identified in higher-grade prostate cancer cells. These findings suggest that Bcl-2psi may be a potential pre-metastatic marker for detection, diagnosis, and therapy during the initiation of metastasis in prostate cancer.