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IntroductionScientific literature regarding the characterization of lymphocyte subpopulations of the cecal appendix is sparse, with few precedents limited to immunohistochemical techniques.MethodsWe conducted a prospective pilot study to characterize lymphocyte subpopulations of the cecal appendix in children. Participants were divided into three groups: (1) patients without histological acute appendiceal inflammation, (2) patients with histological uncomplicated acute appendicitis, and (3) patients with histological complicated acute appendicitis (gangrenous, perforated). A fresh sample of the base of the appendix was taken from all patients and a flow cytometric study was performed. Quantitative variables were compared using Kruskal-Wallis test and Mann-Whitney U test.ResultsThis study included 57 patients divided into Group 1 (n = 5), Group 2 (n = 37), and Group 3 (n = 15). Median values (IQR) of the percentage of B-lymphocytes were 67.8 [66.8-68.1] in group 1, 61.15 [53.74-66.4] in group 2, and 52.1 [33-62.02] in group 3 (p = 0.02). Median values (IQR) of the percentage of NK-lymphocytes were 0.26 [0.2-0.3] in group 1, 0.55 [0.37-0.66] in group 2, and 0.84 [0.35-1.45] in group 3 (p = 0.008). Median values (IQR) of the percentage of T-lymphocytes were 31.9 [31.7-33.1] in group 1, 37.68 [32.15-45.69] in group 2, and 46.9 [37.03-67] in group 3 (p = 0.02). Pair comparisons of groups 2 and 3 also showed significant differences in the percentage of B lymphocytes (p = 0.03) and NK-lymphocytes (p = 0.02).ConclusionsSignificant differences in lymphocyte subpopulations were identified according to the histologic grade of the cecal appendix. More specifically, a lower percentage of B-lymphocytes and a higher percentage of T- and NK-lymphocytes were observed in cases of acute appendicitis. These findings must be confirmed and their etiopathogenic, diagnostic, and prognostic implications elucidated in future studies with larger sample sizes.

Introduction: Scientific literature regarding the characterization of lymphocyte subpopulations of the cecal appendix is sparse, with few precedents limited to immunohistochemical techniques. Methods: We conducted a prospective pilot study to characterize lymphocyte subpopulations of the cecal appendix in children. Participants were divided into three groups: (1) patients without histological acute appendiceal inflammation, (2) patients with histological uncomplicated acute appendicitis, and (3) patients with histological complicated acute appendicitis (gangrenous, perforated). A fresh sample of the base of the appendix was taken from all patients and a flow cytometric study was performed. Quantitative variables were compared using Kruskal-Wallis test and Mann-Whitney U test. Results: This study included 57 patients divided into Group 1 (n = 5), Group 2 (n = 37), and Group 3 (n = 15). Median values (IQR) of the percentage of B-lymphocytes were 67.8 [66.8-68.1] in group 1, 61.15 [53.74-66.4] in group 2, and 52.1 [33-62.02] in group 3 (p = 0.02). Median values (IQR) of the percentage of NK-lymphocytes were 0.26 [0.2-0.3] in group 1, 0.55 [0.37-0.66] in group 2, and 0.84 [0.35-1.45] in group 3 (p = 0.008). Median values (IQR) of the percentage of T-lymphocytes were 31.9 [31.7-33.1] in group 1, 37.68 [32.15-45.69] in group 2, and 46.9 [37.03-67] in group 3 (p = 0.02). Pair comparisons of groups 2 and 3 also showed significant differences in the percentage of B lymphocytes (p = 0.03) and NK-lymphocytes (p = 0.02). Conclusions: Significant differences in lymphocyte subpopulations were identified according to the histologic grade of the cecal appendix. More specifically, a lower percentage of B-lymphocytes and a higher percentage of T- and NK-lymphocytes were observed in cases of acute appendicitis. These findings must be confirmed and their etiopathogenic, diagnostic, and prognostic implications elucidated in future studies with larger sample sizes.

BackgroundApproximately one-third of diffuse large B cell lymphoma (DLBCL) patients exhibit co-expression of MYC and BCL2 (double-expressor lymphoma, DEL) and have a dismal prognosis. Targeted inhibition of the anti-apoptotic protein BCL2 with venetoclax (ABT-199) has been approved in multiple B-cell malignancies and is currently being investigated in clinical trials for DLBCL. Whether BCL2 anti-apoptotic function represents a multifaceted vulnerability for DEL-DLBCL, affecting both lymphoma B cells and T cells within the tumor microenvironment, remains to be elucidated.MethodsHere, we present novel genetically engineered mice that preclinically recapitulate DEL-DLBCL lymphomagenesis, and evaluate their sensitivity ex vivo and in vivo to the promising combination of venetoclax with anti-CD20-based standard immunotherapy.ResultsVenetoclax treatment demonstrated specific killing of MYC+/BCL2(+) lymphoma cells by licensing their intrinsically primed apoptosis, and showed previously unrecognized immunomodulatory activity by specifically enriching antigen-activated effector CD8 T cells infiltrating the tumors. Whereas DEL-DLBCL mice were refractory to venetoclax alone, inhibition of BCL2 significantly extended overall survival of mice that were simultaneously treated with a murine surrogate for anti-CD20 rituximab.ConclusionsThese results suggest that the combination of anti-CD20-based immunotherapy and BCL2 inhibition leads to cooperative immunomodulatory effects and improved preclinical responses, which may offer promising therapeutic opportunities for DEL-DLBCL patients.

Normal B lymphocytes require extrinsic factors to grow and proliferate. Surface receptors (e.g., B-cell antigen receptor, BCR) function, in part, to link growth factors to signal transduction/metabolic pathways and the cell cycle machinery. Accumulating evidence indicates that signal transduction-dependent changes in both glucose energy metabolism and de novo transcription of the D-type cyclin-cdk4/6 pathway are necessary for quiescent B-lymphocytes to enter G1-phase of the cell cycle and grow. B cell growth represents a critical checkpoint for subsequent proliferation and clonal expansion of antigen-specific lymphocytes. On the former, we have shown earlier that acquisition of extracellular glucose and metabolism via the glycolytic pathway is required for conventional splenic B-2 lymphocytes to grow (i.e., increase cell size and mass) in response to antigen challenge; however, the metabolic fate and biological significance of glucose-derived carbons are unknown. Here, we show that in response to BCR ligation, glucose carbon flow is directed into a de novo lipogenic pathway that is regulated, in part, via phosphoinositide-3 kinase (PI-3K)-dependent activation of ATP citrate lyase (ACL), a key rate-limiting enzyme in de novo lipogenesis. Inhibition of ACL results in a loss of B-cell growth and cell viability. Regarding the latter point, the B-1a lymphocyte subset expresses cyclins D2 and D3 that are transiently expressed in a non-overlapping manner, notably cyclin D3 expression immediately precedes the G1/S phase transition, suggesting distinct functions for these D-type cyclins in B-1a lymphocyte G0-to-S phase progression. We show herein that murine B-1a cells deficient in cyclin D3 proliferate normally in response to extracellular stimuli, in part, due to a compensatory sustained up-regulation of cyclin D2. In keeping with this, human diffuse large B-cell lymphoma (DLBCL) represents a malignant clonal expansion of B cells characterized by several subsets, including germinal center (GC) and activated B-cell (ABC) types. Here, we show that the GC-type LY18 human DLBCL exhibits constitutive expression of cyclin D3, but not cyclins D1 and D2. Targeting of cyclin D3-holoenzyme complexes with cell permeable chemical- and peptide-based cdk4 inhibitors results in G1-phase arrest and apoptosis via a pathway that involves inhibition of pRb phosphorylation. By contrast, endogenous knock down of cyclin D3 with siRNA did not induce growth arrest or apoptosis, in part, due to redundancy with cyclin E.

Ets transcription factors have been implicated in the development, regulation, and survival of numerous hematopoietic derived cells, including B and T-lymphocytes. E26 avian leukemia oncogene-2 (Ets-2) is an Ets family member transcription factor. Strong expression of Ets-2 is observed in developing thymocytes from the DN1 stage and in B-cells from the pro-B stage. A conserved sequence within the Ets-2 pointed domain amino acids 69 to 73 PLLTP is able to interact with the Map kinase ERK. Threonine seventy-two is phosphorylated by ERK1, and permits transactivation by Ets-2. Mutation of this residue from a threonine to an alanine, Ets-2 T72A, abrogates Ras mediated transactivation of Ets-2. Based on this evidence, we hypothesized that Ets-2 was important in T- and B-cell development, activation, and function. To test this hypothesis we analyzed Ets-2 activation in T-cell lines, and created two transgenic mice lines that express Ets-2 T72A in either developing T-cells or B-cells. Transactivation of Ets-2 can be induced by both Ras activation and by phorbol 12-myristate 13-acetate and ionomycin stimulation in the Jurkat T-cell line. In-vitro analysis of Ets-2 activation by ionomycin results in a rapid, but transient Ets-2 band shift as evidenced by western blot analysis of protein extracts from thymocytes. Transgenic mice that over-express Ets-2 T72A in the thymus displayed a dramatic reduction in thymus size associated with hypocellularity. This reduction was associated with a partial developmental block at the double negative 2 and double negative 3 stage of development, a twenty-fold increase in c-Kit+ expression, and a five-fold increase the CD5low population. Further, thymocytes from the transgenic mice have increased apoptosis both in-vitro and in-vivo compared to non-transgenic littermates. Transgenic mice that over-express Ets-2 T72A in B-lymphocytes revealed a loss of the B220Hi population of B-cells in the bone marrow. This population consists of mature B-cells that are characterized to be IgM+, IgD+ and Cd49d+ mature lymphocytes. Analysis of transgenic Ets-2 T72A B-cells in other secondary lymph organs did not reveal any defects. This dissertation demonstrates that Ets-2 is an important target in lymphocyte development and function. It is involved in T-cell development and survival and in establishment of mature bone marrow B-cells.

We attempt to identify the plasma membrane transporter involved in the uptake of 5'-deoxy-5-fluorouridine (5'-DFUR), an intermediate metabolite of capecitabine. This novel oral fluoropyrimidine is used in cancer treatments and is a direct precursor of the cytostatic agent 5'-fluorouracil. We also examine the role of the transporter in 5'-DFUR cytotoxicity. The human concentrative nucleoside transporter (hCNT1) was cloned from human fetal liver and expressed in Xenopus laevis oocytes. The two-electrode voltage-clamp technique was used to demonstrate that 5'-DFUR, but not capecitabine or 5'-FU, is an hCNT1 substrate. Then, hCNT1 was heterologously expressed in the mammalian cell line Chinese hamster ovary-K1. Functional expression was demonstrated by monitoring transport of radiolabeled substrates and by using a monospecific polyclonal antibody generated against the transporter. hCNT1-expressing cells were more sensitive to 5'-DFUR than vector-transfected or wild-type cells. The sensitivity of the three cell types to other agents such as cisplatin or 5'-FU was identical. In conclusion, this study shows that 1) the pharmacological profile of a nucleoside transporter can be determined by an electrophysiological approach; 2) the hCNT1 transporter is involved in 5'-DFUR uptake; and 3) hCNT1 expression may increase cell sensitivity to 5'-DFUR treatment. This study also reports for the first time the generation of an antibody against hCNT1, which may be useful in the elucidation of the relationship between hCNT1 expression and tumor response to capecitabine treatment