Factors affecting neutrophil and platelet reconstitution following T cell-depleted bone marrow transplantation: differential effects of growth factor type and role of CD34(+) cell dose.

We have performed univariate and multivariate analysis to determine the factors that affect the kinetics of neutrophil and platelet recovery in 546 recipients of T cell-depleted (TCD) marrow allografts. All patients received marrow depleted of mature CD3(+) T cells by complement-mediated lysis using T(10)B(9)-1A3 (n = 489) or Muromonab-Orthoclone OKT3 (n = 57) monoclonal antibodies. Neutrophil engraftment to 0.5 x 10(9)/1 and platelet engraftment to 20 x 10(9)/l were assessed as endpoints. Factors significantly affecting neutrophil or platelet engraftment in the univariate analysis included patient age, T cell dose, anti-thymocyte globulin use, gender, diagnosis at transplant, CMV serostatus, HLA mismatch, CD34 cell dose (n = 249), and growth factor use and type. These variables were included in the multivariate Cox proportional hazards regression model. The results showed that a faster rate of neutrophil engraftment was independently associated with CD34(+) cell dose > or = 5 x 10(6)/kg and most strongly with growth factor administration. Faster platelet engraftment was associated with transplantation for chronic leukemia, CD34(+) cell dose > or = 2 x 10(6)/kg, an HLA matched related donor, and the absence of growth factor use. G-CSF had a higher relative risk (RR) of enhancing neutrophil engraftment than GM-CSF and significantly delayed platelet engraftment. The combined use of G-CSF + GM-CSF was similar to G-CSF alone. The enhancing effect of G-CSF for neutrophil recovery was most striking for patients who engrafted to 0.5 x 10(9)/1 at or before day 12 (RR = 9.5, P < 0.0001) compared to patients who received no growth factor. Conversely, the delaying effect of G-CSF on platelet engraftment was strongest for patients engrafting on or before day 25 (RR = 0.4, P = 0.0004). Of the independent variables affecting engraftment kinetics in recipients of TCD marrow allografts only growth factor, and to a limited extent, CD34(+) cell dose can be controlled by the clinician. A higher CD34(+) cell dose enhances the rate of both neutrophil and platelet engraftment whereas for G-CSF the benefits of myeloid growth factor use in enhancing neutrophil recovery may be partly offset by a delay in platelet engraftment.

Cytomegalovirus-specific cytolytic T-cell lines and clones generated against adenovirus-pp65-infected dendritic cells.

Cytomegalovirus (CMV) infection is a serious complication of allogeneic bone marrow transplantation (BMT). CMV disease can usually be prevented by passive immunization with donor-derived CMV-pp65-specific T-cell clones if provided early post-BMT. The classic method of generating CMV-specific T-cell clones requires donor-derived fibroblast lines infected with CMV as stimulators, thus limiting the availability of CMV immunotherapy to those patients for whom a donor skin biopsy can be obtained 6 to 8 weeks pretransplantation. To overcome this limitation we have used monocyte-derived dendritic cells (DCs) to induce donor anti-CMV cytotoxic T lymphocytes (CTLs). Matured, adeno-pp65-infected DCs were added at day 0 and at day 7 of a 2-week culture of donor peripheral blood mononuclear cells. DC-primed cultures were compared with cultures stimulated in an identical fashion with CMV-infected fibroblasts or with adeno-pp65-infected freshly isolated blood monocytes. Specific killing of CMV-infected fibroblasts was detected in all except the culture stimulated with pp65-infected monocytes. DCs infected after maturation elicited greater CTL activity than did DCs matured after infection. A series of 5 CD8+ clones from a fibroblast-stimulated culture and 7 CD8+ clones from a mature-DC-stimulated culture derived from a single HLA-A*0201+ individual were characterized. All 12 clones lysed autologous CMV-infected fibroblasts. All except 1 clone from the CMV-infected fibroblast arm (fibroblast arm) lysed vaccinia-pp65-infected B-lymphoblastoid cell lines (BLCLs); none lysed vaccinia-pp150-infected or noninfected BLCLs. Ten of 10 CD8+ clones tested were restricted by HLA-A*0201. Seven of the 12 clones were Vbeta6+ (2 from the fibroblast arm and 5 from the DC arm) with an identical Vbeta6.1-J1.4 sequence. Three clones from the fibroblast arm and 5 clones from the DC arm recognized the pp65 peptide NLVPMVATV (amino acids [aa], 495-503). These data show that CMV-specific T-cell clones with similar restriction patterns, T cell-receptor usage, and specificity can be generated using monocyte-derived pp65-infected-DC or CMV-infected-fibroblast stimulators. This approach should broaden the applicability of CMV-specific T-cell immunotherapy to a wider spectrum of patients by reducing the time required to generate CMV-specific T-cell clones.

Rat cytomegalovirus major immediate-early enhancer switching results in altered growth characteristics.

It has been hypothesized that the major immediate-early (MIE) enhancer of cytomegalovirus (CMV) is important in determining virus tropism and latency because of its essential role in initiating the cascade of early gene expression necessary for virus replication. Although rat CMV (RCMV) and murine CMV (MCMV) exhibit extreme species specificity in vivo, they differ in their ability to replicate in tissue culture. MCMV can replicate in a rat embryo fibroblast (REF) cell line while RCMV does not grow in murine fibroblasts. The tropism is not due to a block in virus entry into the cell. We have constructed a recombinant RCMV in which the RCMV MIE enhancer has been replaced with that of MCMV. Growth of the recombinant virus in tissue culture remains restricted to rat cells, suggesting that other viral and/or host factors are more important in determining in vitro tropism. Unlike findings using recombinant MCMV in which the human CMV (HCMV) MIE enhancer substitutes for the native one (A. Angulo, M. Messerle, U. H. Koszinowski, and P. Ghazal, J. Virol. 72:8502-8509, 1998), infection with our recombinant virus at a low multiplicity of infection resulted in a substantial decrease in virus replication. This occurred despite comparable or increased MIE transcription from the recombinant virus. In vivo experiments showed that the recombinant virus replicates normally in the spleen during acute infection. Notably, the recombinant virus appears to be deficient in spreading to the salivary gland, suggesting a role for the MIE enhancer in tropism for certain tissues involved in virus dissemination. Four months after infection, recombinant virus with the foreign MIE enhancer was reactivated from spleen explants.

Protection from lethal murine graft-versus-host disease without compromise of alloengraftment using transgenic donor T cells expressing a thymidine kinase suicide gene.

Donor T cells play a pivotal role in facilitating alloengraftment but also cause graft-versus-host disease (GVHD). Ex vivo T-cell depletion (TCD) of donor marrow is the most effective strategy for reducing GVHD but can compromise engraftment. This study examined an approach whereby donor T cells are selectively eliminated in vivo after transplantation using transgenic mice in which a thymidine kinase (TK) suicide gene is targeted to the T cell using a CD3 promoter/enhancer construct. Lethally irradiated B10.BR mice transplanted with major histocompatibility complex (MHC)-incompatible TCD C57BL/6 (B6) bone marrow (BM) plus TK(+) T cells were protected from GVHD after treatment with ganciclovir (GCV) in a schedule-dependent fashion. To examine the effect of GCV treatment on alloengraftment, sublethally irradiated AKR mice underwent transplantation with TCD B6 BM plus limiting numbers (5 x 10(5)) of B6 TK(+) T cells. Animals treated with GCV had comparable donor engraftment but significantly reduced GVHD when compared with untreated mice. These mice also had a significantly increased number of donor splenic T cells when assessed 4 weeks after bone marrow transplantation. Thus, the administration of GCV did not render recipients T-cell deficient, but rather enhanced lymphocyte recovery. Adoptive transfer of spleen cells from GCV-treated chimeric mice into secondary AKR recipients failed to cause GVHD indicating that donor T cells were tolerant of recipient alloantigens. These studies demonstrate that administration of TK gene-modified donor T cells can be used as an approach to mitigate GVHD without compromising alloengraftment.

Identification and characterization of a spliced C-type lectin-like gene encoded by rat cytomegalovirus.

The English isolate of rat cytomegalovirus (RCMV) encodes a 20-kDa protein with a C-type lectin-like domain that is expressed in the delayed-early and late phases of the viral replication cycle. Genomic sequence analysis of the restriction fragment KpnR of RCMV revealed significant homology to several C-type lectin-containing molecules implicated in natural killer (NK) and T-cell interactions, as well as genes from four poxviruses and African swine fever virus. The gene is spliced into five exons and shows a splicing pattern with exon boundaries similar to those observed in the human differentiation antigen CD69. The cap site of the gene was mapped by RNase protection, 5' rapid amplification of cDNA ends, and primer extension experiments. This analysis demonstrated that the core promoter of the RCMV lectin-like gene contains a GATA rather than a TATA box. Splicing patterns were confirmed with isolates from an infected-cell cDNA library. A unique aspect of the protein is that its translation is not initiated by the canonical methionine but rather by alanine. To study its role in virus replication and pathogenesis, a recombinant virus was constructed in which the gene is interrupted. Replication in tissue culture was similar to that of wild-type virus.

Analysis of risk factors for the development of GVHD after T cell-depleted allogeneic BMT: effect of HLA disparity, ABO incompatibility, and method of T-cell depletion.

Multivariate analysis was performed to determine the independent factors affecting the risk of acute GVHD (aGVHD) grades II to IV and extensive chronic GVHD (cGVHD) and the rate of survival in 481 recipients of T cell-depleted (TCD) marrow allografts who received transplants at a single center between 1991 and 2000. All patients received grafts partially depleted of CD3+ T cells by complement-mediated lysis using 2 narrow-specificity monoclonal antibodies (MoAbs), T10B9.1A-31 (n = 400) or Muromonab-Orthoclone OKT3 (n = 81). Factors considered in the analysis included patient/donor sex, age, cytomegalovirus (CMV) status, and ABO blood group along with T-cell dose, disease, and disease status, donor relationship, HLA antigen (Ag)mismatch (MM), growth-factor use, anti-thymocyte globulin use, year of transplantation, and the MoAb used for TCD. The results showed an association of HLA with an increased relative risk (RR) of aGVHD for recipients of grafts from relateddonors that were > or =2 Ag MM (n = 73, RR = 2.09, P = .005), matched unrelated (UR) donors (n = 130, RR = 1.98, P = .004), and > or =2 Ag MM UR donors (n = 34, RR = 2.68, P = .003) compared with the baseline matched-sibling group (n = 121). No increased risk of aGVHD was seen for 0 to 1 Ag MM family donors (n = 24) or 1 Ag MM UR donors (n = 99). aGVHD risk was increased with minor, but not major or major-minor, ABO disparity (RR = 2.0, P = .003) compared with that of ABO-identical pairs. We found less effective TCD and resultant higher T-cell dose for recipients of grafts that were T cell depleted using OKT3. However, the use of OKT3 and not the T-cell dose was associated with increased aGVH-D risk (RR of 1.84, P = .001). Increased risk of extensive cGVHD was associated with patient age of >20 years (RR = 2.2, P < .0001) and with CMV status (positive patient/negative donor, RR = 1.9, P = .002). Decreased survival was associated with older age (>20 years), a > or =2 Ag MM related donor, a 1 or > or =2 Ag MM UR donor, risk group, and a CMV-positive patient/-negative donor pair. There was no difference in survival for 0 to 1 Ag MM related or matched UR donors compared with the baseline group. These data indicate that there are quantitative as well as potential qualitative differences in outcome depending on the TCD method. Expected and unexpected risk factors for GVHD and survival were associated with partial TCD. Our data support the consideration of ABO match in donor selection, the preferential selection of CMV-positive donors for CMV-positive recipients, and the acceptance of 1 but not > or =2 Ag HLA MM donors.

Murine gammaherpesvirus 68 cyclin D homologue is required for efficient reactivation from latency.

Murine gammaherpesvirus 68 (MHV68) is a gammaherpesvirus that was first isolated from murid rodents. MHV68 establishes a latent infection in the spleen and other lymphoid organs. Several gammaherpesviruses, including herpesvirus saimiri, human herpesvirus 8, and MHV68, encode proteins with extensive homology to the D-type cyclins. To study the function of the cyclin homologue, a recombinant MHV68 has been constructed that lacks the cyclin homologue and expresses beta-galactosidase as a marker (MHV68(cy-)). MHV68(cy-) grows in vitro with kinetics and to titers similar to those of the wild type. BALB/c mice infected with mixtures of equivalent amounts of the wild type and MHV68(cy-) show deficient growth of the MHV68(cy-) in an acute infection. Infection of SCID mice with virus mixtures also showed decreased MHV68(cy-) virus growth, indicating that the deficiency is not mediated by T or B cells. Although mice infected with mixtures containing 100 times as much MHV68(cy-) had greater splenic titers of the mutant virus than wild-type virus in acute infection, at 28 days postinfection splenocytes from these mice reactivated primarily wild-type virus. Quantitative PCR data indicate that equivalent genomes were present in the latent state. Reinsertion of the cyclin homologue into the cyclin-deleted virus restored the wild-type phenotype. These results indicate that the MHV68 cyclin D homologue mediates important functions in the acute infection and is required for efficient reactivation from latency.

Antiapoptotic herpesvirus Bcl-2 homologs escape caspase-mediated conversion to proapoptotic proteins.

The antiapoptotic Bcl-2 and Bcl-x(L) proteins of mammals are converted into potent proapoptotic factors when they are cleaved by caspases, a family of apoptosis-inducing proteases (E. H.-Y. Cheng, D. G. Kirsch, R. J. Clem, R. Ravi, M. B. Kastan, A. Bedi, K. Ueno, and J. M. Hardwick, Science 278:1966-1968, 1997; R. J. Clem, E. H.-Y. Cheng, C. L. Karp, D. G. Kirsch, K. Ueno, A. Takahashi, M. B. Kastan, D. E. Griffin, W. C. Earnshaw, M. A. Veliuona, and J. M. Hardwick, Proc. Natl. Acad. Sci. USA 95:554-559, 1998). Gamma herpesviruses also encode homologs of the Bcl-2 family. All tested herpesvirus Bcl-2 homologs possess antiapoptotic activity, including the more distantly related homologs encoded by murine gammaherpesvirus 68 (gammaHV68) and bovine herpesvirus 4 (BHV4), as described here. To determine if viral Bcl-2 proteins can be converted into death factors, similar to their cellular counterparts, five herpesvirus Bcl-2 homologs from five different viruses were tested for their susceptibility to caspases. Only the viral Bcl-2 protein encoded by gammaHV68 was susceptible to caspase digestion. However, unlike the caspase cleavage products of cellular Bcl-2, Bcl-x(L), and Bid, which are potent inducers of apoptosis, the cleavage product of gammaHV68 Bcl-2 lacked proapoptotic activity. KSBcl-2, encoded by the Kaposi's sarcoma-associated herpesvirus, was the only viral Bcl-2 homolog that was capable of killing cells when expressed as an N-terminal truncation. However, because KSBcl-2 was not cleavable by caspases, the latent proapoptotic activity of KSBcl-2 apparently cannot be released. The Bcl-2 homologs encoded by herpesvirus saimiri, Epstein-Barr virus, and BHV4 were not cleaved by apoptotic cell extracts and did not possess latent proapoptotic activities. Thus, herpesvirus Bcl-2 homologs escape negative regulation by retaining their antiapoptotic activities and/or failing to be converted into proapoptotic proteins by caspases during programmed cell death.

Strain specific effects of cytomegalovirus on endothelial cells: implications for investigating the relationship between CMV and cardiac allograft vasculopathy.

BACKGROUND: Cytomegalovirus (CMV) has been associated with the development of chronic allograft rejection. Attempts to delineate pathogenetic mechanisms for this association have characteristically used well-established laboratory strains for in vitro investigation and rodent strains for in vivo studies. There is substantial genetic heterogeneity not only among different laboratory strains, but also between laboratory strains and clinical isolates, and genetic differences between human and animal strains are profound. Given these genetic differences, one would anticipate differences in biological activity between strains. METHODS: Vascular endothelial cells were infected with two laboratory strains of CMV (Towne and AD-169) as well as two individual clinical CMV isolates, after genetic typing with six segments of the genome (including early and late genes). mRNA expression coding for a panel of mesenchymal growth factors was studied using quantitative reverse transcription, polymerase chain reaction. Major histocompatibility complex (MHC) expression was investigated using flow cytometry. RESULTS: There was substantial genetic variability between clinical and laboratory isolates. There did not appear to be differences in overall infectivity by the different strains as determined by expression of immediate-early antigen at 24 hours (5-10% of endothelial cells positive for immediate-early. Two growth factors, platelet-derived growth factor-A and basic fibroblast growth factor were augmented by one of the two clinical strains of CMV (Clin 2) (P=0.0091 and P=0.0018, respectively). Transforming growth factor -alpha and insulin-like growth factor expression were significantly reduced by both clinical strains and AD-169. Two other growth factors, heparin-binding epidermal growth factor and transforming growth factor-beta were not altered by infection with any strain. No strain altered MHC class II expression. MHC class I expression was increased with one of the two clinical strains (Clin 1, P=0.0006) and decreased by AD-169 (P=0.0016). Clin 2 and Towne had no effect on MHC class I expression. CONCLUSIONS: These data demonstrate that the genetic heterogeneity of CMV is associated with differences in transplant-relevant biologic activity even among clinical isolates. The relationship between CMV and chronic rejection may be difficult to determine given the heterogeneous nature of this complex virus.

Comparison of immediate and in-hospital results of conventional balloon and perfusion balloon angioplasty using intracoronary ultrasound.

Angiographic studies have demonstrated that perfusion balloon percutaneous transluminal coronary angioplasty (PTCA) may result in modestly improved luminal gains and fewer major dissections than conventional balloon PTCA. However, intracoronary ultrasound (ICUS), which is more sensitive than angiography in evaluating the incidence, extent, and severity of dissection, was not used. We randomized 48 patients with 54 coronary stenoses to conventional or perfusion balloon PTCA. Four 2-minute inflations were permitted with conventional balloon PTCA. Two 10-minute inflations were allowed with perfusion balloon PTCA. Quantitative coronary angiography and ICUS were performed before and after treatment. In-hospital clinical events were recorded. Conventional and perfusion balloon PTCA achieved similar improvements in lumen diameter (1.25+/-0.51 vs 1.28+/-0.51 mm) and reductions in percent stenosis (-45+/-21% vs -44+/-15%) by quantitative coronary angiography. Comparable gains in lumen diameter (0.62+/-0.39 vs 0.50+/-0.38 mm) and lumen area (2.70+/-1.96 vs 2.05+/-1.52 mm2) were observed on ICUS. Angiography demonstrated similar rates of any dissection (36% vs 21%) and major dissection (12% vs 7%). ICUS identified a similar incidence of any dissection (60% vs 76%) and type II dissection (52% vs 62%). The relative dissection area was also similar (9.2+/-5.6% vs 7.8+/-5.8%). One conventional balloon patient experienced postprocedural chest pain. No patient in either group died, or had myocardial infarction, abrupt closure, or urgent revascularization.

Treatment of autoimmune disease by intense immunosuppressive conditioning and autologous hematopoietic stem cell transplantation.

Multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis are immune-mediated diseases that are responsive to suppression or modulation of the immune system. For patients with severe disease, immunosuppression may be intensified to the point of myelosuppression or hematopoietic ablation. Hematopoiesis and immunity may then be rapidly reconstituted by reinfusion of CD34(+) progenitor cells. In 10 patients with these autoimmune diseases, autologous hematopoietic stem cells were collected from bone marrow or mobilized from peripheral blood with either granulocyte colony-stimulating factor (G-CSF) or cyclophosphamide and G-CSF. Stem cells were enriched ex vivo using CD34(+) selection and reinfused after either myelosuppressive conditioning with cyclophosphamide (200 mg/kg), methylprednisolone (4 g) and antithymocyte globulin (ATG; 90 mg/kg) or myeloablative conditioning with total body irradiation (1,200 cGy), methylprednisolone (4 g), and cyclophosphamide (120 mg/kg). Six patients with multiple sclerosis, 2 with systemic lupus erythematosus, and 2 with rheumatoid arthritis have undergone hematopoietic stem cell transplantation. Mean time to engraftment of an absolute neutrophil count greater than 500/microL (0.5 x 10(9)/L) and a nontransfused platelet count greater than 20,000/microL (20 x 10(9)/L) occurred on day 10 and 14, respectively. Regimen-related nonhematopoietic toxicity was minimal. All patients improved and/or had stabilization of disease with a follow-up of 5 to 17 months (median, 11 months). We conclude that intense immunosuppressive conditioning and autologous T-cell-depleted hematopoietic transplantation was safely used to treat these 10 patients with severe autoimmune disease. Although durability of response is as yet unknown, all patients have demonstrated stabilization or improvement.

Recurrent acyclovir-resistant herpes simplex in an immunocompromised patient: can strain differences compensate for loss of thymidine kinase in pathogenesis?

To investigate how acyclovir-resistant (ACVr) herpes simplex virus (HSV) evades drug therapy and causes disease, HSV-1 isolates from a bone marrow transplant (BMT) patient were studied. The patient developed ACVr disease after an initial BMT and, following a second BMT, reactivated ACVr HSV despite high-dose acyclovir prophylaxis. ACVr isolates from each episode contained the same point mutation in the viral thymidine kinase (tk) gene, documenting the emergence, latency, and reactivation of this mutant. The mutants were exceedingly impaired for TK activity in sensitive enzyme, plaque autoradiography, and drug-susceptibility assays. Nevertheless, these mutants and a tk deletion mutant constructed in the same genetic background reactivated from latency in mouse trigeminal ganglia, in contrast to similar mutants from laboratory strains. It is hypothesized that alleles in the clinical isolate compensate for the loss of TK in this animal model. Such genetic variability may be important for ACVr disease in humans.

T cell-depleted autologous hematopoietic stem cell transplantation for multiple sclerosis: report on the first three patients.

Multiple sclerosis (MS) is a disease of the central nervous system characterized by immune-mediated destruction of myelin. In patients with progressive deterioration, we have intensified immunosuppression to the point of myeloablation. Subsequently, a new hematopoietic and immune system is generated by infusion of CD34-positive hematopoietic stem cells (HSC). Three patients with clinical MS and a decline of their Kurtzke extended disability status scale (EDSS) by 1.5 points over the 12 months preceding enrollment and a Kurtzke EDSS of 8.0 at the time of enrollment were treated with hematopoietic stem cell (HSC) transplantation using a myeloablative conditioning regimen of cyclophosphamide (120 mg/kg), methylprednisolone (4 g) and total body irradiation (1200 cGy). Reconstitution of hematopoiesis was achieved with CD34-enriched stem cells. The average time of follow-up is 8 months (range 6-10 months). Despite withdrawal of all immunosuppressive medications, functional improvements have occurred in all three patients. We conclude that T cell-depleted hematopoietic stem cell transplantation can be performed safely in patients with severe and debilitating multiple sclerosis. Stem cell transplantation has resulted in modest neurologic improvements for the first time since onset of progressive disease although no significant changes in EDSS or NRS scales are evident at this time.

Adoptive immunotherapy for leukemia: donor lymphocytes transduced with the herpes simplex thymidine kinase gene for remission induction. HGTRI 0103.

This study will evaluate the safety and efficacy of allogenic donor lymphocyte infusions in patients who have relapsed hematologic malignancies after allogeneic bone marrow transplantation (BMT). Donor lymphocyte transfusions have resulted in the cure of some patients with relapsed leukemia or lymphoproliferative disorder after allogeneic BMT, but has been complicated by the development of graft versus host disease (GvHD). We hypothesize that a retroviral vector containing the Herpes simplex thymidine kinase (HStk) gene will allow for retention of the anti-leukemia response of transfused donor lymphocytes while allowing for the adverse effects of GVHD to be mitigated. Patients with relapsed hematologic malignancies after allogeneic BMT will be infused with ex vivo gene modified donor lymphocytes. The Herpes Simplex thymidine kinase (HStk) gene will be transduced into the cells ex vivo using LTKOSN. 1 vector supernate. Insertion of the HStk gene into lymphocytes confers a sensitivity to the anti-herpes drug ganciclovir (GCV). This selective destruction of donor lymphocytes in situ will be used to abrogate the effect of graft versus host disease, if it develops.

Kaposi's sarcoma-associated human herpesvirus-8 encodes homologues of macrophage inflammatory protein-1 and interleukin-6.

Human herpesvirus-8 (HHV-8) has been detected in Kaposi's sarcoma (KS) lesions of all types (AIDS-related, classical and endemic), in body-cavity-based B-cell lymphomas (BCBLs) and in lesions of multicentric Castleman's disease (MCD). We have identified a major gamma-herpesvirus-divergent locus (DL-B) in HHV-8 DNA encoding several HHV-8 unique open reading frames (ORFs), including a homologue of interleukin-6 (IL-6) and two homologues of macrophage inflammatory protein MIP-1. We show that the HHV-8-encoded IL-6 homologue (vIL-6) shares functional properties with endogenous IL-6 proteins and that both vIL-6 and vMIP-1 transcripts are present at high levels following butyrate induction of an HHV-8' BCBL cell line. Low amounts of constitutive vIL-6, but not vMIP-1, mRNA were also detected. The presence of a functional IL-6 homologue encoded by HHV-8 may provide a mechanistic model for the hypothesized role of HHV-8 in KS, MCD and BCBL that involves the mitogenic effects of vIL-6 on surrounding cells. MIP-1 proteins may enhance these effects through the chemotactic recruitment of endogenous cytokine-producing cells into affected tissues and could potentially influence HIV disease progression in coinfected individuals through interactions with the HIV co-receptor CCR-5.

Rat cytomegalovirus has a unique immediate early gene enhancer.

The immediate early (IE) enhancer/promoter regions of human cytomegalovirus (HCMV), simian cytomegalovirus (SCMV), and murine cytomegalovirus (MCMV) share the following characteristics: (1) they demonstrate high-level transcriptional properties, (2) multiple repetitive elements are found throughout the enhancer region, and (3) consensus binding sites for cellular transcription factors are frequently located within the repetitive elements. Here we characterize the enhancer/promoter region of the major IE gene locus for rat cytomegalovirus (RCMV). The RCMV IE enhancer/promoter region is able to activate transcription at the same level as HCMV or MCMV IE enhancer/promoter regions. In contrast to HCMV, MCMV, and SCMV, the RCMV IE enhancer/promoter region is almost completely lacking in repetitive elements and the only recognized consensus binding sites for cellular transcription factors recognized by sequence are three CTF, two AP1, and one NF-kappa B binding sites. However, enhancing activity does not appear to be dependent on these individual sites in transient transfection experiments, but is additive across the enhancer region.

Paradoxic effect of anti-CD4 therapy on lacrimal gland disease in MRL/Mp-lpr/lpr mice.

PURPOSE: MRL/Mp-lpr/lpr mice (MRL/lpr) spontaneously develop lacrimal gland inflammatory lesions and are a model for the human disease Sjögren's syndrome. Therapy with monoclonal antibodies (mAb) to CD4 ameliorates the autoimmune renal, vasculitic, and intraocular inflammatory lesions in MRL/lpr mice. The effect of anti-CD4 mAb therapy on lacrimal gland immunopathology was evaluated. METHODS: From 1 to 5 months of age, MRL/lpr mice were treated with weekly intraperitoneal injections of 2 mg anti-CD4 mAb, after which they were killed and their lacrimal glands were removed for histologic evaluation and immunocytochemistry. Control mice were administered weekly intraperitoneal injections of either saline or normal rat immunoglobulin. RESULTS: Anti-CD4 mAb treatment produced no reduction in lacrimal gland inflammation but did change its morphology. In control mice, there were multiple sharply delineated foci of inflammatory cells in the lacrimal gland, whereas in anti-CD4 mAb-treated mice, there was a more diffuse inflammation surrounding ill-defined foci that spread throughout the gland. Immunocytochemistry revealed that in control mice, lesions were composed predominantly of CD4+ T cells, but in anti-CD4 mAb-treated mice, CD8+ T cells predominated. CONCLUSIONS: Although anti-CD4 mAb therapy of MRL/lpr mice eliminated autoimmune renal disease, autoantibody formation, and ocular inflammatory disease, it had a paradoxic effect on lacrimal gland lesions. Lacrimal gland lesions in the anti-CD4 mAb-treated mice were not decreased, but they had a different morphology and a different immunocytochemical profile.

Characterization of the major locus of immediate-early genes of rat cytomegalovirus.

A major locus of rat cytomegalovirus (RCMV) immediate-early (IE) RNA transcription was identified. A cDNA library from rat embryo fibroblasts infected with RCMV under IE conditions was constructed and screened by using appropriate RCMV DNA probes, revealing at least two IE genes (IE1 and IE2) transcribed from this locus by differential splicing. The first three exons (the first is noncoding) are spliced to exon 4 to form IE1 and to exon 5 to form IE2. The structural organization of the RCMV major IE region is therefore similar to that of human cytomegalovirus (HCMV) and murine cytomegalovirus (MCMV). When we compared the predicted amino acid sequences of the IE1 proteins of RCMV, HCMV, and MCMV, no areas of homology were found across all three proteins, while a few small areas of homology were found between RCMV IE1 and MCMV IE1. In contrast, large areas of homology were found across the carboxyl half of RCMV IE2, HCMV IE2, and MCMV ie3 proteins. In addition, similarities were found at the beginning of exon 5 of RCMV and MCMV. The possible significance of these conserved regions is discussed. Dinucleotide frequency analysis demonstrated a decrease in CpG frequency over the IE region. The IE gene products were able to transactivate heterologous promoters.