C. J. M. Van Noesel

Functional and phenotypic evidence for a selective loss of memory T cells in asymptomatic human immunodeficiency virus-infected men.

In addition to a well-documented depletion of CD4+ T helper cells in later stages of human immunodeficiency virus (HIV) infection, evidence has been provided for a specific unresponsiveness to triggering either by specific antigen in the context of autologous major histocompatibility molecules (self + X) or anti-CD3 monoclonal antibodies (MAb) in both CD4 and CD8 cells from asymptomatic HIV-infected individuals. In the present study we analyzed this unresponsiveness using mitogenic antibodies to distinct T cell membrane receptors. T cells from HIV-infected men who had normal numbers of CD4+ T cells responded poorly to activation signals via the CD3 membrane antigen in both accessory cell-dependent as well as accessory cell-independent culture systems. A similar low response was observed in an anti-CD2-driven system. In contrast, proliferation induced by anti-CD3, anti-CD2, or the phorbol ester Phorbol myristate acetate could be normally enhanced by anti-CD28 MAb. We demonstrated that this unresponsiveness is not due to a failure to induce early events required for activation, such as increased intracellular concentration of free calcium and activation of protein kinase C, but is caused by an imbalance between naive and memory T cells. In HIV-infected asymptomatic men, CD29+ memory T cells are selectively depleted which results in a poor responsiveness to self + X. These findings provide new insights that may have implications for our understanding of the immunopathogenesis of AIDS.

MOLECULAR PATHWAYS IN FOLLICULAR LYMPHOMA

Follicular lymphoma (FL) is one of the most common B-cell non-Hodgkins lymphomas. The initiating genetic event found in ∼90% of FL is the t(14;18), causing constitutive expression of the antiapoptotic BCL-2 protein. The exact secondary alterations leading to full FL development are still poorly defined. In this review, we address (i) the genetic pathways associated with tumorigenesis and progression of FL, (ii) the role of micro-environmental factors with emphasis on B-cell receptor ligands and (iii) lymphoma models in mice and what they teach us about lymphomagenesis in man.

High incidence of Kaposi sarcoma-associated herpesvirus infection in HIV-related solid immunoblastic/plasmablastic diffuse large B-cell lymphoma

Kaposi sarcoma-associated herpesvirus (KSHV) is known to be associated with two distinct lymphoproliferative disorders: primary effusion lymphoma (PEL) and multicentric Castleman disease (MCD)/MCD-associated plasmablastic lymphoma. We here report a high incidence of KSHV infection in solid HIV-associated immunoblastic/plasmablastic non-Hodgkins lymphomas (NHLs), in patients lacking effusions and without evidence of (prior) MCD. Within a cohort of 99 HIV-related NHLs, 10 cases were found to be KSHV positive on the basis of immunostaining for KSHV LNA-1 as well as KSHV-specific polymerase chain reaction. All but one of the tumors coexpressed Epstein–Barr virus. Interestingly, all KSHV-positive cases belonged to a distinctive subgroup of 26 diffuse large B-cell lymphomas characterized by the expression of CD138 (syndecan-1) and plasmablastic/immunoblastic morphology. These KSHV-positive lymphomas were preceded by Kaposi sarcoma in 60% of the patients and involved the gastrointestinal tract in 80%. Our results indicate that KSHV infection is not restricted to PEL and MCD; it is also common (38%) in HIV-related solid immunoblastic/plasmablastic lymphomas.

Topical 5-fluorouracil treatment of anal intraepithelial neoplasia in human immunodeficiency virus-positive men

Background  Anal intraepithelial neoplasia (AIN), a human papillomavirus (HPV)‐induced potential precursor lesion of anal cancer, is frequent among human immunodeficiency virus (HIV)‐positive men who have sex with men (MSM). So far, only a few prospective studies have been performed on the topical treatment of AIN, especially at the intra‐anal location.

A novel chronic lymphocytic leukemia subset expressing mutated IGHV3-7-encoded rheumatoid factor B-cell receptors that are functionally proficient.

A novel chronic lymphocytic leukemia subset expressing mutated IGHV3-7-encoded rheumatoid factor B-cell receptors that are functionally proficient

The BMP pathway either enhances or inhibits the Wnt pathway depending on the SMAD4 and p53 status in CRC

Background:Constitutive Wnt activation is essential for colorectal cancer (CRC) initiation but also underlies the cancer stem cell phenotype, metastasis and chemosensitivity. Importantly Wnt activity is still modulated as evidenced by higher Wnt activity at the invasive front of clonal tumours termed the β-catenin paradox. SMAD4 and p53 mutation status and the bone morphogenetic protein (BMP) pathway are known to affect Wnt activity. The combination of SMAD4 loss, p53 mutations and BMP signalling may integrate to influence Wnt signalling and explain the β-catenin paradox.Methods:We analysed the expression patterns of SMAD4, p53 and β-catenin at the invasive front of CRCs using immunohistochemistry. We activated BMP signalling in CRC cells in vitro and measured BMP/Wnt activity using luciferase reporters. MTT assays were performed to study the effect of BMP signalling on CRC chemosensitivity.Results:Eighty-four percent of CRCs with high nuclear β-catenin staining are SMAD4 negative and/or p53 aberrant. BMP signalling inhibits Wnt signalling in CRC only when p53 and SMAD4 are unaffected. In the absence of SMAD4, BMP signalling activates Wnt signalling. When p53 is lost or mutated, BMP signalling no longer influences Wnt signalling. The cytotoxic effects of 5-FU are influenced in a similar manner.Conclusions:The BMP signalling pathway differentially modulates Wnt signalling dependent on the SMAD4 and p53 status. The use of BMPs in cancer therapy, as has been proposed by previous studies, should be targeted to individual cancers based on the mutational status of p53 and SMAD4.

Chlamydia psittaci -negative ocular adnexal marginal zone B-cell lymphomas have biased V H 4-34 immunoglobulin gene expression and proliferate in a distinct inflammatory environment

Ocular adnexal marginal zone B-cell lymphomas (OAMZLs) arise in the connective tissues of the orbit or in the mucosa-associated lymphoid tissue of the conjunctiva. Here, we present the immunological and genetic analyses of 20 primary Chlamydia psittaci (Cp)-negative OAMZLs. Analysis of the immunoglobulin variable heavy chain (IgVH) gene usage demonstrated a significant preference for VH4-34. A combined analysis across all previously published OAMZLs confirmed that this is a general feature of OAMZL, in particular of the Cp-negative group. Our series of OAMZLs did not express the characteristic rheumatoid factor VHDJH rearrangements that were previously found in salivary gland- and gastric-marginal zone B-cell lymphomas (MZBCLs). We did not detect the MZBCL-specific chromosomal translocations, t(11;18) API2-MALT1 (mucosa-associated lymphoid tissue1) and t(14;18) IgH/MALT1. Two cases contained a premature stop codon in the A20 gene (TNFAIP3) and one case harbored the activating MYD88 hotspot mutation L265P. Variable nuclear expression of BCL10, NFκB1 (p50) and NFκB2 (p52) suggests that other additional genetic abnormalities affecting the NFκB pathway exist within this group of lymphomas. OAMZL showed variable expression of the chemokine receptor CXCR3 and integrin α4β7 by the tumor B cells, and low interferon-γ and interlukin-4 mRNA levels in the tissue, indicative of an inflammatory environment with features in between those previously found in cutaneous and other extranodal MZBCL. The strongly biased usage of VH4-34 in Cp-negative OAMZLs suggests involvement of a particular stimulatory (auto-) antigen in their development.

Radiation-induced melanoma-associated leucoderma, systemic antimelanoma immunity and disease-free survival in a patient with advanced-stage melanoma: a case report and immunological analysis

Background  Melanoma is an immunogenic tumour. The development of skin depigmentation or melanoma‐associated leucoderma (MAL) has been associated with favourable clinical outcome in patients with metastatic melanoma, especially after immunotherapy. Evidence for clinically meaningful enhancement of melanoma‐directed autoimmunity, as indicated by MAL, after radiotherapy without immunotherapy has not yet been published.

Biased Iglambda expression in hypermutated IgD multiple myelomas does not result from receptor revision.

Normal IgM−IgD+ CD38+ B cells and IgM−IgD+ multiple myelomas (MM) are characterized by Cμ deletion, biased Igλ expression and hypermutated IgV regions. The predominant Igλ usage has been proposed as resulting from secondary Ig gene rearrangements during extensive clonal expansion in the germinal center environment. Here, four cases of IgDλ MM were studied to address the question of light chain receptor revision in a ‘single cell’ model. Detailed analyses of both IGK and IGL alleles of each case were performed by Southern blotting, (RT-) PCR, and sequencing. The expressed IgV genes were extensively mutated and Cμ deletion was confirmed in two cases. In addition, in the four MM a total of six non-functional deletional IGK rearrangements were identified, which proved to be unmutated. We conclude that IgD myelomas indeed originate from (post) germinal center B cells in which, in spite of the fact that they are hypermutated, there is no evidence of receptor revision.

Immunoglobulin diversification in B cell malignancies: internal splicing of heavy chain variable region as a by-product of somatic hypermutation

In this study we describe alternative splicing of somatically mutated immunoglobulin (Ig) variable heavy chain (VH) genes in three distinct primary B cell non-Hodgkins lymphomas (B-NHL). In two V4–34 expressing lymphomas, ie a post-germinal center type B cell chronic lymphocytic leukemia (B-CLL) and a follicular lymphoma (FL), internally spliced VH gene transcripts were found in which a sequence stretch of 116 bp between the framework region 1 (FR1) and complementarity determining region 2 (CDR2) had been deleted. We provide evidence that for this alternative IgVH mRNA processing a known cryptic 5′ splice donor site and a previously unidentified cryptic 3′ splice acceptor site were used. Site-directed mutagenesis showed that the cryptic 3′ splice acceptor site had been activated by specific somatic point mutations. The B-CLL further harbored a triplication of the rearranged JH3 gene segment including the putative N region and part of the JH3-JH4 intron sequence. This triplication probably took place via a repeated mechanism of DNA double strand break followed by homologous recombination, a mechanism which was recently proposed also involved in the somatic hypermutation process and is compatible with the post-germinal center derivation of this B-CLL. Finally, in a V4–34 expressing diffuse large B cell lymphoma, we observed alternative IgVH mRNA processing using the same cryptic 5′ splice donor site and the normal splice acceptor site of the CH1-Cμ exon. The significance of alternative IgVH processing in B cell malignancies and as a potential mechanism of somatic Ig diversification is discussed.