Purpose: The microenvironment influences outcome in follicular lymphoma. Our hypothesis was that several immune cell subsets are important for disease outcome and their individual prognostic importance should be demonstrable in the same analysis and in competition with clinical factors.Experimental Design: Seventy follicular lymphoma patients with extreme clinical outcome ("poor" and "good" cases) were selected in a population-based cohort of 197. None of the 37 good-outcome patients died from lymphoma, whereas all the 33 poor-outcome patients succumbed in ≤5 years. Furthermore, the good-outcome patients were followed for a long time and needed no or little treatment. A tissue microarray was constructed from diagnostic, pretreatment biopsies. Cellular subsets were quantified after immunostaining, using computerized image analysis, separating cells inside and outside the follicles (follicular and interfollicular compartments). Flow cytometry data from the same samples were also used.Results: Independently of the Follicular Lymphoma International Prognostic Index, CD4 + cells were associated with poor outcome and programmed death-1-positive and CD8 + cells were associated with good outcome. The prognostic values of CD4 + and programmed death-1-positive cells were accentuated when they were follicular and that of CD8 + cells were accentuated when they were interfollicular. Follicular FOXP3 + cells were associated with good outcome and interfollicular CD68 + cells were associated with poor outcome. Additionally, high CD4/CD8 and CD4 follicular/interfollicular ratios correlated with poor outcome. Conclusion: There are many important immune cell subsets in the microenvironment of follicular lymphoma. Each of these is independently associated with outcome. This is the first study showing the effect of the balance of the entire microenvironment, not only of individual subsets.

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The online version of this article has a Supplementary Appendix. BackgroundPlasmablastic lymphoma has recently come to be considered a distinct entity among mature B cell neoplasms, although the limits with diffuse large B-cell lymphoma (DLBCL) need to be more accurately defined. Design and MethodsHere we show the results of an immunohistochemical study of 35 cases of plasmablastic lymphoma compared with a set of 111 conventional DLBCLs . ResultsOur results demonstrate that the use of a limited combination of immunohistochemical markers (PAX5&CD20, PRDM1/BLIMP1 and XBP1s) enables the identification of a plasmablastic immunophenotype highly characteristic of plasmablastic lymphoma cases and associated with an aggressive clinical behavior. Additionally, the study shows that the acquisition of a partial plasmablastic phenotype (PRDM1/BLIMP1 expression) in DLBCL is associated with shorter survival in R-CHOP-treated patients. ConclusionsThe use of a restricted combination of immunohistochemical markers (PAX5&CD20, PRDM1/BLIMP1 and XBP1s) enables a more accurate definition of terminal differentiation for large B-cell lymphoma.Key words: plasmablastic lymphoma, terminal B-cell differentiation. Citation: Montes-Moreno S, Gonzalez-Medina

The CDKN2A gene located on chromosome region 9p21 encodes the cyclin-dependent kinase-4 inhibitor p16/INK4A, a negative cell cycle regulator. We analyzed p16/INK4A expression in different types of non-Hodgkin's lymphoma to determine whether the absence of this protein is involved in lymphomagenesis, while also trying to characterize the genetic events underlying this p16/INK4A loss. To this end, we investigated the levels of p16/INK4A protein using immunohistochemical techniques in 153 cases of non-Hodgkin's lymphoma, using as reference the levels found in reactive lymphoid tissue. The existence of gene mutation, CpG island methylation, and allelic loss were investigated in a subset of 26 cases, using single-strand conformational polymorphism and direct sequencing, Southern Blot, polymerase chain reaction, and microsatellite analysis, respectively. Loss of p16/INK4A expression was detected in 41 of the 112 non-Hodgkin's lymphomas studied (37%), all of which corresponded to high-grade tumors. This loss of p16/INK4A was found more frequently in cases showing tumor progression from mucosa-associated lymphoid tissue low-grade lymphomas (31 of 37) or follicular lymphomas (4 of 4) into diffuse large B-cell lymphomas. Analysis of the status of the p16/INK4A gene showed different genetic alterations (methylation of the 5'-CpG island of the p16/INK4A gene, 6 of 23 cases; allelic loss at 9p21, 3 of 16 cases; and nonsense mutation, 1 of 26 cases). In all cases, these events were associated with loss of the p16/INK4A protein. No case that preserved protein expression contained any genetic change. Our results demonstrate that p16/INK4A loss of expression contributes to tumor progression in lymphomas. The most frequent genetic alterations found were 5'-CpG island methylation and allelic loss.