Allosuppressor and allohelper T cells in acute and chronic graft-vs.-host disease. II. F1 recipients carrying mutations at H-2K and/or I-A.

By induction of a graft-vs.-host reaction (GVHR) in nonirradiated H-2-different F1 mice, one can induce stimulatory pathological symptoms, such as lymphadenopathy and hypergammaglobulinemia, combined with the production of autoantibodies characteristic of systemic lupus erythematosus (SLE). Alternatively, the GVHR can lead to the suppressive pathological symptoms, such as pancytopenia and hypogammaglobulinemia, characteristic of acute GVH disease (GVHD). Whether stimulatory or suppressive symptoms are induced by a GVHR depends, in our view (2-4), on the functional subset of donor T cells activated in the F1 host. The purpose of the present study was to investigate whether class I and/or class II H-2 alloantigens can selectively trigger, out of a pool of unselected donor T cells, those subpopulations of T cells responsible for the stimulatory and suppressive GVH symptoms, respectively. For the induction of the GVHR, 10(8) lymphoid cells from C57BL/6 (B6) donors were injected into three kinds of F1 hybrid mice, which had been bred from H-2 mutant strains on a B6 background. Whereas the I-A-disparate (B6 X bm12)F1 recipients exclusively developed stimulatory GVH symptoms, including SLE-like autoantibodies and immune complex glomerulonephritis, the K locus-disparate (B6 X bm1)F1 recipients showed neither clearly stimulatory nor clearly suppressive GVH symptoms. In marked contrast, the (bm1 X bm12)F1 recipients, which differ from the B6 donor strain by mutations at both K and I-A locus, initially developed stimulatory GVH symptoms, but rapidly thereafter showed the suppressive pathological symptoms of acute GVHD and died. Moreover, spleen cells obtained from (B6 X bm12)F1 mice injected with B6 donor cells helped the primary anti-sheep erythrocyte (SRBC) response of normal (B6 X bm12)F1 spleen cells in vitro, whereas spleen cells (bm1 X bm12)F1 mice injected with B6 donor cells strongly suppressed the primary anti-SRBC response of normal (bm1 X bm12)F1 spleen cells. Spleen cells from the K locus-disparate (B6 X bm1)F1 recipients also suppressed the primary anti-SRBC of normal (B6 X bm1)F1 spleen cells; this suppression, however, was weak when compared with the suppression induced by spleen cells from GVH (bm1 X bm12)F1 mice. Taken together, these findings indicate that a small class II (I-A) antigenic difference suffices to trigger the alloreactive donor T helper cells causing SLE-like GVHD. In contrast, both class I (H-2K) and class II (I-A) differences are required to trigger the subsets of donor T cells responsible for acute GVHD. It appears that alloreactive donor T helper cells induce the alloreactive T suppressor cells, which then act as the suppressor effector cells causing the pancytopenia of acute GVHD. These findings may help to understand the variability of GVH-like diseases caused by a given etiologic agent, their cellular pathogenesis, and association with certain HLA loci.

Allosuppressor and allohelper T cells in acute and chronic graft-vs-host disease. V. F1 mice with secondary chronic GVHD contain F1-reactive allohelper but no allosuppressor T cells.

We studied the alloreactive properties of donor T cells obtained from F1 mice that had recovered from the allosuppression of acute graft-vs.-host disease (GVHD) and showed mild symptoms of chronic GVHD, i.e., so-called secondary chronic GVHD. To this end, we used (B10 x DBA/2)F1 mice that had been injected with 10(8) B10 spleen cells 100-150 d previously. Such GVHD F1 mice were repopulated by lympho-hematopoietic cells of donor (B10) origin, which exhibited split tolerance towards the host: Whereas F1-specific donor T helper (Th) cells as well as T cells proliferating in the mixed lymphocyte reaction were readily demonstrable, F1-specific T suppressor (Ts) and T killer (Tk) cells were not, or were hardly, detectable; responses against third-party alloantigens were normal. Upon adoptive transfer to nonirradiated secondary recipients, the B10 cells obtained from the repopulated GVH F1 mice induced F1-specific enlargement of the draining popliteal lymph node and enhancement of the IgG formation therein. B10 cells of the same kind were unable, however, to induce lethal GVHD upon transfer to 950 rad-irradiated secondary (B10 x DBA/2)F1 recipients. We conclude that alloactivated donor Ts/Tk cells disappear from the host at a relatively early stage of GVHD, i.e., at the end of acute GVHD , presumably because they are short-lived. By contrast, the longevity of alloactivated donor Th cells causes the symptoms of secondary chronic GVHD.

Regulation of cytokine signaling by B cell antigen receptor and CD40-controlled expression of heparan sulfate proteoglycans.

Recently, biochemical, cell biological, and genetic studies have converged to reveal that integral membrane heparan sulfate proteoglycans (HSPGs) are critical regulators of growth and differentiation of epithelial and connective tissues. As a large number of cytokines involved in lymphoid tissue homeostasis or inflammation contain potential HS-binding domains, HSPGs presumably also play important roles in the regulation of the immune response. In this report, we explored the expression, regulation, and function of HSPGs on B lymphocytes. We demonstrate that activation of the B cell antigen receptor (BCR) and/or CD40 induces a strong transient expression of HSPGs on human tonsillar B cells. By means of these HSPGs, the activated B cells can bind hepatocyte growth factor (HGF), a cytokine that regulates integrin-mediated B cell adhesion and migration. This interaction with HGF is highly selective since the HSPGs did not bind the chemokine stromal cell-derived factor (SDF)-1 alpha, even though the affinities of HGF and SDF-1alpha for heparin are similar. On the activated B cells, we observed induction of a specific HSPG isoform of CD44 (CD44-HS), but not of other HSPGs such as syndecans or glypican-1. Interestingly, the expression of CD44-HS on B cells strongly promotes HGF-induced signaling, resulting in an HS-dependent enhanced phosphorylation of Met, the receptor tyrosine kinase for HGF, as well as downstream signaling molecules including Grb2-associated binder 1 (Gab1) and Akt/protein kinase B (PKB). Our results demonstrate that the BCR and CD40 control the expression of HSPGs, specifically CD44-HS. These HSPGs act as functional coreceptors that selectively promote cytokine signaling in B cells, suggesting a dynamic role for HSPGs in antigen-specific B cell differentiation.

Allosuppressor and allohelper T cells in acute and chronic graft-vs-host disease. I. Alloreactive suppressor cells rather than killer T cells appear to be the decisive effector cells in lethal graft-vs.-host disease.

Splenic T cells from B10 donors were injected into irradiated (B10 x DBA/2)F1 mice. Either 5 or 6 d later, activated donor T cells were recovered from the spleens of these primary F1 (1 degree F1) recipients and transferred to groups of nonirradiated syngeneic F1 (2 degrees F1) recipients. Whereas day-5-activated parental T cells induced the characteristic symptoms of acute graft-vs.-host disease (GVHD) and eventually lethal GVHD, day-6-activated B10 T cells failed to induce acute GVHD but induced symptoms of chronic GVHD. Interestingly, the inability of day-6-activated T cells to induce lethal GVHD could not be ascribed to a lack in anti-F1 T killer cells. The combined results of functional studies indicated that day-6 cells were enriched for alloreactive helper T cells, whereas day-5 cells were enriched for alloreactive suppressor cells. Hence, our findings indicate that acute GVHD and lethal GVHD are caused by alloreactive donor T suppressor but not T killer cells, and that symptoms of chronic GVHD are caused by alloreactive donor T helper cells.

Activated human lymphocytes and aggressive non-Hodgkin's lymphomas express a homologue of the rat metastasis-associated variant of CD44.

A recently described splice variant of CD44 expressed in metastasizing cell lines of rat tumors, has been shown to confer metastatic potential to nonmetastasizing rat pancreatic carcinoma and sarcoma cell lines. Using antibodies raised against a bacterial fusion protein encoded by variant CD44 sequences, we have explored the expression of variant CD44 glycoproteins on human lymphoid cells and tissues and on non-Hodgkin's lymphomas. Normal lymphohematopoietic cells express barely detectable low levels of variant CD44 glycoproteins, whereas T lymphocytes, upon activation by mitogen or antigen, transiently upregulate expression of specific CD44 variant glycoproteins. The reaction pattern of various antibodies indicates that these CD44 variants contain the domain encoded by exon v6, which is part of the variant that in the rat confers metastatic capability. It is interesting that overexpression of v6 was also found in several aggressive, but not low-grade, non-Hodgkin's lymphomas.

Paracrine regulation of germinal center B cell adhesion through the c-met-hepatocyte growth factor/scatter factor pathway.

T cell-dependent humoral immune responses are initiated by the activation of naive B cells in the T cell areas of the secondary lymphoid tissues. This primary B cell activation leads to migration of germinal center (GC) cell precursors into B cell follicles where they engage follicular dendritic cells (FDC) and T cells, and differentiate into memory B cells or plasma cells. Both B cell migration and interaction with FDC critically depend on integrin-mediated adhesion. To date, the physiological regulators of this adhesion were unkown. In the present report, we have identified the c-met-encoded receptor tyrosine kinase and its ligand, the growth and motility factor hepatocyte growth factor/scatter factor (HGF/SF), as a novel paracrine signaling pathway regulating B cell adhesion. We observed that c-Met is predominantly expressed on CD38(+)CD77(+) tonsillar B cells localized in the dark zone of the GC (centroblasts). On tonsil B cells, ligation of CD40 by CD40-ligand, induces a transient strong upregulation of expression of the c-Met tyrosine kinase. Stimulation of c-Met with HGF/SF leads to receptor phosphorylation and, in addition, to enhanced integrin-mediated adhesion of B cells to both VCAM-1 and fibronectin. Importantly, the c-Met ligand HGF/SF is produced at high levels by tonsillar stromal cells thus providing signals for the regulation of adhesion and migration within the lymphoid microenvironment.

Adhesion of human B cells to follicular dendritic cells involves both the lymphocyte function-associated antigen 1/intercellular adhesion molecule 1 and very late antigen 4/vascular cell adhesion molecule 1 pathways.

Presentation of antigen in the form of immune complexes to B lymphocytes by follicular dendritic cells (FDC) is considered to be a central step in the generation of memory B cells. During this process, which takes place in the microenvironment of the germinal center, B cells and FDC are in close physical contact. In the present study, we have explored the molecular basis of FDC-B cell interaction by using FDC and B cells derived from human tonsils. We found that FDC express high levels of the adhesion receptors intercellular adhesion molecule 1 (ICAM-1 [CD54]) and vascular cell adhesion molecule 1 (VCAM-1), while the B lymphocytes express lymphocyte function-associated antigen 1 (LFA-1 [CD11a/18]), very late antigen 4 (VLA-4 [CD49d], and CD44. Furthermore, we established that both the LFA-1/ICAM-1 and VLA-4/VCAM-1 adhesion pathways are involved in FDC-B lymphocyte binding, and therefore, these pathways might be essential in affinity selection of B cells and in the formation of B memory cells.

Tuberculosis preventive treatment opportunities at antiretroviral therapy initiation and follow-up visits.

SETTING: Twenty-two clinics providing HIV care and treatment in Botswana where tuberculosis (TB) and HIV comorbidity is as high as 49%. OBJECTIVES: To assess eligibility of TB preventive treatment (TPT) at antiretroviral therapy (ART) initiation and at four follow-up visits (FUVs), and to describe the TB prevalence and associated factors at baseline and yield of TB diagnoses at each FUV. DESIGN: A prospective study of routinely collected data on people living with HIV (PLHIV) enrolled into care for the Xpert® MTB/RIF Package Rollout Evaluation Study between 2012 and 2015. RESULTS: Of 6041 PLHIV initiating ART, eligibility for TPT was 69% (4177/6041) at baseline and 93% (5408/5815); 95% (5234/5514); 96% (4869/5079); and 97% (3925/4055) at FUV1, FUV2, FUV3, and FUV4, respectively. TB prevalence at baseline was 11% and 2%, 3%, 3% and 6% at each subsequent FUV. At baseline, independent risk factors for prevalent TB were CD4 <200 cells/mm3 (aOR = 1.4, P = 0.030); anemia (aOR = 2.39, P < 0.001); cough (aOR = 11.21, P < 0.001); fever (aOR = 2.15, P = 0.001); and weight loss (aOR = 2.60, P = 0.002). CONCLUSION: Eligibility for TPT initiation is higher at visits post-ART initiation, while most cases of active TB were identified at ART initiation. Missed opportunities for TB further compromises TB control effort among PLHIV in Botswana.

MARCO DE REFERENCIA: Veintidós consultorios que prestan atención y tratamiento relacionados con la infección por el virus de la inmunodeficiencia humana (VIH) en Botswana, donde la comorbilidad por tuberculosis (TB) e infección por el VIH puede alcanzar 49%. OBJETIVOS: Evaluar los criterios para recibir el tratamiento preventivo de la TB (TPT) durante las consultas de iniciación y seguimiento del tratamiento antirretrovírico (TAR) y describir la prevalencia de TB y los factores asociados en el momento del inicio y el rendimiento del diagnóstico de TB en cada cita de seguimiento del TAR. MÉTODO: Fue este un estudio prospectivo de los datos obtenidos sistemáticamente en las personas con infección por el VIH (PLHIV), inscritas en la atención para el estudio de evaluación del despliegue de la prueba Xpert® MTB/RIF del 2012 al 2015. RESULTADOS: De los 6041 PLHIV que iniciaron el TAR, 69% (4177/6041) cumplía los criterios para recibir el TPT al comienzo; 93% (5408/5815) en la primera consulta de seguimiento; 95% (5234/5514) en la segunda; 96% (4869/5079) en la tercera; y 97% (3925/4075) en la cuarta cita de seguimiento. La prevalencia inicial de TB fue 11% y durante el seguimiento fue 2%, 3%, 3% y 6%, respectivamente. Al comienzo del TAR, los factores de riesgo independientes de diagnóstico de TB fueron una cifra de linfocitos CD4 <200 células/mm3 (aOR 1,4; P = 0,030), la anemia (aOR 2,39; P < 0,001), la tos (aOR 11,21; P = <0,001), la fiebre (aOR 2,15; P = 0,001) y la pérdida de peso (aOR 2,60; P = 0,002). CONCLUSIÓN: Los pacientes cumplen las condiciones para recibir el TPT con mayor frecuencia en las consultas posteriores al comienzo del TAR, pero la mayoría de los casos de TB activa se detecta al iniciarlo. Las oportunidades desaprovechadas para detectar casos de TB dificultan aún más el control de esta enfermedad en las PLHIV en Botswana.

Improving sputum collection processes to increase tuberculosis case finding among HIV-positive persons in Botswana.

SETTING: Twenty-two human immunodeficiency virus (HIV) clinics in Botswana. OBJECTIVE: To compare sputum collection rates, sputum quality and volume, and tuberculosis (TB) diagnosis rates before and after field efforts to improve sputum collection among individuals newly diagnosed with HIV with TB symptoms. DESIGN: Newly diagnosed individuals living with HIV attending 22 HIV clinics in Botswana were screened for TB from August 2012 to March 2014. Starting in May 2013, a field intervention composed of the introduction of a tracking log for presumed TB patients, and patient instructions and sputum induction to improve sputum collection rates was implemented. RESULTS: Prior to the intervention, sputum collection rates were 44.1% (384/870). Subsequently, sputum collection increased to 58.3% (579/993) (P < 0.001). Sputum quality and volume also improved. Although rates of TB diagnosis increased from 9.7% (84/870) to 12.5% (120/993), this difference was not significant (P = 0.143). CONCLUSION: Sputum collection rates among presumptive TB cases, as well as sputum quality and volume improved after implementation of the field intervention. To improve sputum collection rates, efforts at the program level should be ongoing.

A human homologue of the rat metastasis-associated variant of CD44 is expressed in colorectal carcinomas and adenomatous polyps.

A recently described splice variant of CD44 expressed in metastasizing cell lines of rat tumors has been shown to confer metastatic potential to a non-metastasizing rat pancreatic carcinoma cell line and to non-metastasizing sarcoma cells. Homologues of this variant as well as several other CD44 splice variants are also expressed at the RNA level in human carcinoma cell lines from lung, breast, and colon, and in immortalized keratinocytes. Using antibodies raised against a bacterial fusion protein encoded by variant CD44 sequences, we studied the expression of variant CD44 glycoproteins in normal human tissues and in colorectal neoplasia. Expression of CD44 variant proteins in normal human tissues was readily found on several epithelial tissues including the squamous epithelia of the epidermis, tonsils, and pharynx, and the glandular epithelium of the pancreatic ducts, but was largely absent from other epithelia and from most non-epithelial cells and tissues. In human colorectal neoplasia CD44 variant proteins, including homologues of those which confer metastatic ability to rat tumors, were found on all invasive carcinomas and carcinoma metastases. Interestingly, focal expression was also observed in adenomatous polyps, expression being related to areas of dysplasia. The distribution of the CD44 variants in human tissues suggests that they play a role in a few restricted differentiation pathways and that in colorectal tumors one of these pathways has been reactivated. The finding that metastasis-related variants are already expressed at a relatively early stage in colorectal carcinogenesis and tumor progression, i.e., in adenomatous polyps, suggests the existence of a yet unknown selective advantage linked to CD44 variant expression. The continued expression in metastases would be compatible with a role in the metastatic process.

Assessment of routine screening of pediatric contacts of adults with tuberculosis disease in Tanzania.

SETTING: Ten selected healthcare facilities in Tanzania, March-April 2016. OBJECTIVE: To assess the implementation of screening among pediatric contacts of adults with tuberculosis (TB) disease. DESIGN: Using a mixed-methods approach, we conducted a questionnaire study among sputum smear-positive adult TB patients and abstracted data from their patient cards to assess the implementation of a child contact management (CCM) intervention. We also conducted in-depth interviews with healthcare workers (HCWs) to solicit their views on clinical practices and challenges in CCM. RESULTS: A total of 141 adult smear-positive TB patients reported 396 children living in households; detailed information on 346 (87.4%) was available. Only 37 (10.7%) children were clinically assessed for TB, 5 (13.5%) were diagnosed with TB, and 22 started on isoniazid preventive therapy (IPT) (59.0%). Of the 320 children whose caregivers responded to whether their children had undergone human immunodeficiency virus (HIV) testing, 55 (17.2%) had been tested and one (1.8%) was HIV-positive. Forty-one HCWs described passive CCM without use of contact or IPT registers. CONCLUSION: We identified gaps in the implementation of TB screening, IPT provision, and HIV testing in pediatric contacts of adults with sputum smear-positive TB. Systematic efforts, including increasing HCW training and educating the community, may improve implementation.

Treatment outcomes, diagnostic and therapeutic impact: Xpert vs. smear. A systematic review and meta-analysis.

BACKGROUND: Compared with smear microscopy, Xpert® MTB/RIF has the potential to reduce delays in tuberculosis (TB) diagnosis and treatment initiation, and improve treatment outcomes. We reviewed publications comparing treatment outcomes of drug-susceptible TB patients diagnosed using Xpert vs. smear. METHODS: Citations (2000-2016) reporting treatment outcomes of patients diagnosed using Xpert compared with smear were selected from PubMed, Scopus and conference abstracts. We conducted a systematic review and meta-analysis. Favorable (cured, completed) and unfavorable (failure, death, loss to follow-up) outcomes were pooled for meta-analysis; we also reviewed the number of TB cases diagnosed, time to treatment and empiric treatment. The Mantel-Haenszel method with a fixed-effect model was used; I² was calculated to measure heterogeneity. RESULTS: From 13 citations, 43 594 TB patients were included and 4825 were with known TB treatment outcome. From the pooled analysis, an unfavorable outcomes among those diagnosed using Xpert compared with smear was 20.2%, 541/2675 vs. 21.9%, 470/2150 (risk ratio 0.92, 95%CI 0.82-1.02). Statistical heterogeneity was low (I² = 0.0%, P = 0.910). Compared with smear, Xpert was reported to be superior in increasing the number of TB patients diagnosed (2/9 citations), increasing bacteriologically confirmed TB (7/9 citations), reducing empiric treatment (3/5 citations), reducing time to diagnosis (2/3 citations), and reducing time to treatment initiation (1/5 citations). CONCLUSIONS: Xpert implementation showed no discernible impact on treatment outcomes compared with conventional smear despite reduced time to diagnosis, time to treatment or reduced level of empiric treatment. Further research is required to learn more about gaps in the existing health system.

Significantly improved PCR-based clonality testing in B-cell malignancies by use of multiple immunoglobulin gene targets. Report of the BIOMED-2 Concerted Action BHM4-CT98-3936.

Polymerase chain reaction (PCR) assessment of clonal immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements is an important diagnostic tool in mature B-cell neoplasms. However, lack of standardized PCR protocols resulting in a high level of false negativity has hampered comparability of data in previous clonality studies. In order to address these problems, 22 European laboratories investigated the Ig/TCR rearrangement patterns as well as t(14;18) and t(11;14) translocations of 369 B-cell malignancies belonging to five WHO-defined entities using the standardized BIOMED-2 multiplex PCR tubes accompanied by international pathology panel review. B-cell clonality was detected by combined use of the IGH and IGK multiplex PCR assays in all 260 definitive cases of B-cell chronic lymphocytic leukemia (n=56), mantle cell lymphoma (n=54), marginal zone lymphoma (n=41) and follicular lymphoma (n=109). Two of 109 cases of diffuse large B-cell lymphoma showed no detectable clonal marker. The use of these techniques to assign cell lineage should be treated with caution as additional clonal TCR gene rearrangements were frequently detected in all disease categories. Our study indicates that the BIOMED-2 multiplex PCR assays provide a powerful strategy for clonality assessment in B-cell malignancies resulting in high Ig clonality detection rates particularly when IGH and IGK strategies are combined.

Delay in the Provision of Antiretroviral Therapy to HIV-infected TB Patients in Nigeria.

BACKGROUND: Nigeria has a high burden of HIV and tuberculosis (TB). To reduce TB-associated morbidity and mortality, the World Health Organization recommends that HIV-positive TB patients receive antiretroviral therapy (ART) within eight weeks of TB treatment initiation, or within two weeks if profoundly immunosuppressed (CD4<50 cell/µL). METHODS: TB and HIV clinical records from facilities in two Nigerian states between October 1st, 2012 and September 30th, 2013 were retrospectively reviewed to assess uptake and timing of ART initiation among HIV-positive TB patients. Healthcare workers were qualitatively interviewed to assess TB/HIV knowledge and barriers to timely ART. RESULTS: Data were abstracted from 4,810 TB patient records, of which 1,249 (26.0%) had HIV-positive or unknown HIV status documented, and the 574 (45.9%) HIV-positive TB patients were evaluated for timing of ART uptake relative to TB treatment. Among 484 (84.3%) HIV-positive TB patients not already on ART, 256 (52.9%, 95% CI: 45.0-60.8) were not initiated on ART during six months of TB treatment. 30.0% of 273 patients with a known CD4≥50cells/µL started ART within eight weeks, and 14.8% of 54 patients with a known CD4<50cells/µL started within the recommended two weeks. Only 42% of health workers interviewed reported knowing to interpret guidelines on when to initiate ART in HIV-positive TB patients based on CD4 cell count results. CD4 cell count significantly predicted timely ART uptake. CONCLUSION: A large proportion of HIV-positive TB patients were not initiated on ART early or even at all during TB treatment. Retraining of staff, and interventions to strengthen referral systems should be implemented to ensure timely provision of ART among HIV-positive TB patients in Nigeria.

Loss of CYLD expression unleashes Wnt signaling in multiple myeloma and is associated with aggressive disease.

Deletion or mutation of the gene encoding the deubiquitinating enzyme CYLD is a common genomic aberration in multiple myeloma (MM). However, the functional consequence of CYLD loss and the mechanism underlying its putative role as a tumor suppressor gene in the pathogenesis of MM has not been established. Here, we show that CYLD expression is highly variable in myeloma cell lines and primary MMs and that low CYLD expression is associated with disease progression from monoclonal gammopathy of undetermined significance to MM, and with poor overall and progression free-survival of MM patients. Functional assays revealed that CYLD represses MM cell proliferation and survival. Furthermore, CYLD acts as a negative regulator of NF-κB and Wnt/ß-catenin signaling and loss of CYLD sensitizes MM cells to NF-κB-stimuli and Wnt ligands. Interestingly, in primary MMs, low CYLD expression strongly correlated with a proliferative and Wnt signaling-gene expression signature, but not with an NFκB target gene signature. Altogether, our findings identify CYLD as a negative regulator of NF-κB and Wnt/ß-catenin signaling in MM and indicate that loss of CYLD enhances MM aggressiveness through Wnt pathway activation. Thus, targeting the Wnt pathway could be a promising therapeutic strategy in MM with loss of CYLD activity.

Heparan sulfate proteoglycan binding promotes APRIL-induced tumor cell proliferation.

APRIL, a proliferation-inducing ligand, is a member of the tumor necrosis factor (TNF) family that is expressed by various types of tumors and influences their growth in vitro and in vivo. Two receptors, transmembrane activator and cyclophilin ligand interactor (TACI) and B-cell maturation antigen (BCMA), bind APRIL, but neither is essential for the tumor-promoting effects, suggesting that a third receptor exists. Here, we report that APRIL specifically binds to heparan sulfate proteoglycans (HSPG) on the surface of tumor cells. This binding is mediated by the heparin sulfate side chains and can be inhibited by heparin. Importantly, BCMA and HSPG do not compete, but can bind APRIL simultaneously, suggesting that different regions in APRIL are critical for either interaction. In agreement, mutation of three lysines in a putative heparin sulfate-binding motif, which is not part of the TNF fold, destroys interaction with HSPG, while binding to BCMA is unaffected. Finally, whereas interaction of APRIL with HSPG does not influence APRIL-induced proliferation of T cells, it is crucial for its tumor growth-promoting activities. We therefore conclude that either HSPG serve as a receptor for APRIL or that HSPG binding allows APRIL to interact with a receptor that promotes tumor growth.

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-Hodgkin's 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.

Expression of CD44 variant proteins in human colorectal cancer is related to tumor progression.

Specific CD44 variant glycoproteins are overexpressed at particular stages of colorectal tumor progression. Some variants of the CD44 glycoprotein without exon v6 sequences appear at the earliest stage of tumorigenesis, i.e., in early adenomas. Expression of variants containing exon v6 sequences is largely restricted to the advanced stages of tumor development and in addition is more prevalent and intense in metastatic (Dukes C/D) than in nonmetastatic (Dukes A/B) carcinomas. The observation that CD44 variants containing a protein domain of CD44 that confers full metastatic potential to rat carcinoma and sarcoma cell lines is increasingly expressed during colorectal tumor progression indicates that this domain may have an important role in tumor progression and metastasis in humans. Information on v6 expression, which can be obtained by routine immunohistochemistry, may prove of important prognostic value, particularly in carcinomas (Dukes A and B) that have not yet given rise to detectable metastases.

Evaluation of a TB infection control implementation initiative in out-patient HIV clinics in Zambia and Botswana.

SETTING: Out-patient human immunodeficiency virus (HIV) care and treatment clinics in Zambia and Botswana, countries with a high burden of HIV and TB infection. OBJECTIVE: To develop a tuberculosis infection control (TB IC) training and implementation package and evaluate the implementation of TB IC activities in facilities implementing the package. DESIGN: Prospective program evaluation of a TB IC training and implementation package using a standardized facility risk assessment tool, qualitative interviews with facility health care workers and measures of pre- and post-test performance. RESULTS: A composite measure of facility performance in TB IC improved from 32% at baseline to 50% at 1 year among eight facilities in Zambia, and from 27% to 80% at 6 months among 10 facilities in Botswana. Although there was marked improvement in indicators of managerial, administrative and environmental controls, key ongoing challenges remained in ensuring access to personal protective equipment and implementing TB screening in health care workers. CONCLUSION: TB IC activities at out-patient HIV clinics in Zambia and Botswana improved after training using the implementation package. Continued infrastructure support, as well as monitoring and evaluation, are needed to support the scale-up and sustainability of TB IC programs in facilities in low-resource countries.

The hepatocyte growth factor/Met pathway in development, tumorigenesis, and B-cell differentiation.

This article summarizes the structure, signal transduction and physiologic functions of the HGF/Met pathway, as well as its role in tumor growth, invasion, and metastasis. Moreover, it highlights recent studies indicating a role for the HGF/Met pathway in antigen-specific B-cell development and B-cell neoplasia.