Distinct subsets of dendritic cells resembling dermal DCs can be generated in vitro from monocytes, in the presence of different serum supplements

We recently demonstrated that dendritic cells (DCs) can be generated from monocytes in the presence of high concentrations of human serum (HS), provided the extra-cellular pH is maintained at plasma values. Because monocyte-derived DCs (Mo-DCs) can also be generated in the presence of fetal calf serum (FCS) or serum-free medium, we have investigated whether these different culture supplements influence DC generation. With this aim, purified monocytes were cultured with GM-CSF plus IL-4 for 6 days and were further exposed to TNF-alpha for 2 additional days, in the presence of HS, autologous plasma (AP), FCS, or X-VIVO 20, a serum-free medium. Our results show that good yields of functionally mature DCs can reproducibly be obtained in the presence of HS or AP, as assessed by CD83 and CD86 up-regulation, dextran-FITC uptake, allogeneic MLR assays and the induction of an autologous response. Interestingly, the effect of serum on DC generation was probably not only quantitative, but also qualitative, since (i) the majority of HS- or AP-cultured DCs expressed CD83 with very weak levels of CD1a, whereas CD83+ DCs cultured in FCS or X-VIVO were mostly CD1a++; (ii) HS- and AP-cultured DCs were much more granular and heterogeneous than FCS- or X-VIVO-cultured DCs, and (iii) the presence of Birbeck-like granules was preferentially observed in HS- or AP-cultured DCs, as assessed by electron microscopy. That these different cells resemble dermal DCs (DDCs) was further supported by the observations that most of the cells displayed intracytoplasmic FXIIIa in the absence of Lag antigen, and expressed E-cadherin at very low levels. Altogether, our results indicate that starting from the same monocytic population, different subsets of DCs can be generated, depending on the culture conditions. Thus, HS or AP favors the generation of fully mature DCs that resemble activated dermal DCs, whereas FCS, or X-VIVO preferentially leads to the generation of less mature CD1a++ dermal-like DCs.

A rapid one-stage whole-blood HPA-1a phenotyping assay using a recombinant monoclonal IgG1 anti-HPA-1a

Severe neonatal alloimmune thrombocytopenia and patients with HPA-1a-specific antibodies require transfusion of HPA-1a-negative platelets. Identifying HPA-1a-negative donors requires simple and reliable typing methods. Most existing techniques use polyclonal antibodies, are time consuming and involve platelet isolation. We have used a horseradish peroxidase (HRP)-conjugated recombinant IgG1 anti-HPA-1a (CAMTRAN007) to develop a rapid and reliable enzyme-linked immunosorbent assay (ELISA), which eliminates sample preparation and reduces the incubation and wash steps associated with traditional sandwich ELISAs. The assay uses simultaneous incubation of the monoclonal antibody RFGP56 to capture GPIIbIIIa from whole blood and the recombinant IgG1 antibody to detect captured HPA-1a antigen. It allows 96 samples to be typed in less than 1 h and can be used on stored samples. Initial testing of 85 samples of known HPA-1a genotype demonstrated that HPA-1a-negative samples had OD values of < 0.266, whereas HPA-1a-positive samples had OD values of > 0.6. Testing of 1862 random donor samples in two blood centres confirmed these OD cut-off values and identified 45 HPA-1a-negative samples (2.4%), all except one giving OD values of < 0.2. The remaining HPA-1a-negative sample had an OD value of 0.303. The HPA-1a status on all the negative samples and an equivalent number of randomly selected positive samples was confirmed by flow cytometry and polymerase chain reaction with sequence-specific primers (PCR- SSP).

Characterization of a canine long-term T cell line (DLC 01) established from a dog with Sézary syndrome and producing retroviral particles

The canine DLC 01 cell line derives from a lymph node of a dog with Sézary syndrome. The DLC 01 cell phenotype is CD4-, CD8+, CD45+, DQ+, similar to that of original cells after treatment with dimethylsulfoxide or phorbol myristate. Canine cutaneous T cell lymphoma are usually CD4-, CD8+ in contrast to their human counterparts which are CD4+, CD8-. Therefore, the DLC 01 cell line appears to be a unique model to study the mechanism of all surface molecule expression in vitro. Viral particles with retrovirus type-C morphology were found in ultrathin sections of DLC 01 cell pellets. Retroviral particles are spontaneously produced after the 50th cell passage or after induction with 0.5% dimethylsulfoxide. This is the first description of a dog lymphoid cell line spontaneously growing and producing a retrovirus. It was found to share several features in common with feline and murine leukemia viruses.

[Application of the gel test using and anti-IgA antiglobulin for the immunologic diagnosis of autoimmune hemolytic anemia with a negative direct Coombs test]

Autoimmune hemolytic anemias (AIHA) are characterized by hyperhemolysis associated with the presence of the immunoglobulins IgG, IgM or IgA on the red cell membrane. These immunoglobulins react as auto-antibodies against the red cell auto-antigens of the patient. The diagnosis is supported by clinical and biological signs of hemolysis, and by the identification of the auto-antibodies using the direct antiglobulin test (DAT). Here we report 14 cases of patients who showed the clinical and biological profile of AIHA, but who gave a negative DAT. We therefore tried to determine the presence of IgA on the red cell membrane with a method more sensitive than the DAT: the gel test using anti-IgA. With such a gel test, we demonstrated that there were IgA auto-antibodies on the red cell membrane in the 14 cases, therefore confirming the diagnosis of AIHA. We discuss the interest of performing a gel test with anti-IgA in each case where AIHA is suspected, but in which a negative DAT has been observed.

[Surgical technique of limbal autotransplantation in severe and recent eye burns]

We report our surgical technique of limbal autograft for recent severe ocular burns. Our procedure is a modified Kenyon and Tseng technique. We discuss our main observations when using this procedure for serious ocular burns which demonstrate the physical signs best indicating surgery, the limbal region to be used, and optimal postoperative follow-up.

[Hepatitis G virus in blood donors]

PURPOSE

Anti-hepatitis C virus (HCV) antibodies (Abs) screening on blood donors has been introduced in France on March 1st, 1990. During the last years, a new agent named Hepatitis G Virus (HGV) has been described. We have tested different groups of blood donors with the aim of establishing the prevalence of the HGV.

METHODS

Two hundred and forty-three donors negative for anti-HCV Abs, other viral markers and with normal Alanine Amino Transferase (ALT) as control [group 1], 91 with elevated ALT [group 2], 72 with Abs directed against the hepatitis B virus core (Anti-HBc) [group 3], 3 with elevated ALT and anti-HBc Abs [group 4] and 70 positive for anti-HCV Abs [group 5] were evaluated. HCV-RNA was tested by Polymerase Chain Reaction (PCR) (Amplicor, Roche) and HGV-RNA by in house PCR and Abbott Kit. Anti-HGV Abs were tested with Boehringer and/or Abbott tests.

RESULTS

Among group 1, none subject is found HCV-RNA positive. Seven (2.9%) are HGV viremic and 19 positive for anti-HGV Abs (7.8%). Four (4.4%) and 5 (6.9%) donors were HGV-RNA positive and 15 (16.5%) and 16 (22.2%) anti-HGV Abs positive in group 2 and 3 respectively. In group 4, 2 donors are anti-HGV Abs positive. Furthermore, in group 5, 52 subjects (74.3%) are HCV-RNA positive and 9 HGV-RNA positive (12.9%). Six donors are viremic for the both viruses. Lastly, 26 donors have anti-HGV Abs (37.1%). None subject of the five groups has both HGV-RNA and anti-HGV Abs.

CONCLUSION

The prevalence of HGV-RNA and anti-HGV is high among control donors. In donors with one or two hepatitis surrogate markers (ALT and/or anti-HBc Abs), the prevalence of HGV viremia and anti-HGV Abs is increased as well as among donors with HCV infection.

In vitro and in vivo reversal of cancer cell multidrug resistance by the semi-synthetic antibiotic tiamulin

A large number of multidrug resistance (MDR) modulators, termed chemosensitizers, have been identified from a variety of chemicals, but most have been proven to be clinically toxic. Low concentrations of the pleuromutilin-derived semi-synthetic antibiotic tiamulin (0.1 to 10 microM) sensitized the three highly resistant P-glycoprotein (Pgp)-overexpressing tumor cell lines P388 (murine lymphoid leukemia), AS30-D (rat hepatoma), CEM (human lymphoblastic leukemia), and the barely resistant AS30-D/S cell lines to several MDR-related anticancer drugs. Flow cytometric analysis showed that tiamulin significantly increased the intracellular accumulation of daunomycin. When compared to reference modulating agents such as verapamil and cyclosporin A, tiamulin proved to be 1.1 to 8.3 times more efficient in sensitizing the resistant cell lines. Moreover, when given i.p. (1.6 microg/mg body weight), tiamulin increased the survival rate of adriamycin-treated mice bearing the P388/ADR25 tumor line by 29%. In the presence of an anticancer drug, tiamulin inhibited both ATPase and drug transport activities of Pgp in plasma membranes from tumor cells. Tiamulin is thus a potent chemosensitizer that antagonizes the Pgp-mediated chemoresistance in many tumor cell lines expressing the MDR phenotype at different levels and displays no toxic effects on contractile tissues at active doses, therefore providing the promise for potential clinical applications.

Factors associated with successful mobilization of peripheral blood progenitor cells in 200 patients with lymphoid malignancies

Peripheral blood progenitor cells (PBPC) were mobilized and harvested in 200 patients treated for non-Hodgkin's lymphoma (n = 148), Hodgkin's disease (n = 22) and multiple myeloma (n = 30). The variables predicting the collection of a minimal (>2.5 x 10(6)/kg) or a high (>10 x 10(6)/kg) CD34+ cell count were analysed. Patients were mobilized with haemopoietic growth factors following either standard chemotherapy (n = 49) or high-dose cyclophosphamide, given alone (n = 55) or combined with high-dose VP16 (n = 86). 10 patients received haemopoietic growth factors only. The first mobilization resulted in a PBPC harvest with enough CD34+ cells in 179/200 patients (90%). High-dose cyclophosphamide, with or without VP16, did not mobilize a higher progenitor cell yield than standard chemotherapy. When performing multiple regression analysis in the 190 patients who received chemotherapy-containing mobilization, only the number of previous chemotherapy regimens and the exposure to fludarabine predicted for a failure to collect a minimal PBPC count (P=0.06 and 0.0008 respectively). The target to collect a high CD34+ cell count was negatively associated with the number of previous chemotherapy regimens (P=0.002). When only non-Hodgkin's lymphoma patients were considered for multivariate analysis, low-grade histology with fludarabine appeared to be associated with poor PBPC cell yield (P=0.08 and 0.005 respectively). This data confirms that PBPC harvest should be planned early in the disease course in transplant candidates, and can be obtained after a standard course of chemotherapy.

Generation of stable monocyte-derived dendritic cells in the presence of high concentrations of homologous or autologous serum: influence of extra-cellular pH

Recent studies have highlighted the high degree of differentiation of monocytes. Indeed, dendritic cells (DC) can be generated from monocytes, in the presence of appropriate cytokines. However, human serum is usually avoid in such cultures. Here, we report that human serum does not inhibit generation of mature DC from blood monocytes, but rather that extra-cellular pH may play an important role in the regulation of monocyte differentiation. Indeed, monocytes cultured at pH 7.4 in the presence of high concentrations of human serum developed efficiently into mature DC, as opposed with monocytes cultured at pH 7. These pH 7.4 cultured DC presented features characteristic of mature DC, at the phenotypical, functional and morphological levels. In addition, these DC were stable, with respect to their sustained expression of CD83 and CD86, upon withdrawal of cytokines. Finally, when autologous plasma was used instead of homologous serum, differentiation of monocytes into mature DC was efficient, as well. Thus, altogether, our data show the importance of extra-cellular pH on differentiation of monocyte-derived DC in the presence of human serum, which should be maintained at plasma levels.

Genetic polymorphisms in the tumor necrosis factor locus influence non-Hodgkin's lymphoma outcome

Systemic release of tumor necrosis factor (TNF) and lymphotoxin-alpha (LTalpha) has been found to contribute to the severity of non-Hodgkin's lymphoma (NHL). We investigated whether genetic polymorphisms in the TNF locus, previously shown to influence TNF and LTalpha genes expression, might contribute to these cytokines production and to the clinical course of NHL. Genomic DNA from 273 lymphoma patients was typed for TNF (-308) polymorphism using an allele-specific polymerase chain reaction (PCR) and for LTalpha (+252) polymorphism with a PCR-based restriction fragment length polymorphism. The presence of the TNF allele involved in increased TNF gene transcription was associated with higher plasma levels of this cytokine at the time of lymphoma diagnosis (chi2 test, P = .013). An extended haplotype analysis showed that the presence of at least two TNF or LTalpha high-producer alleles constituted a risk factor for first-line treatment failure (chi2 test, P = .021), shorter progression-free survival (log-rank test, P = .0007), and overall survival (log-rank test, P = .012). In the subgroup of 126 patients with diffuse large-cell lymphoma, the presence of two or more TNF/LTalpha high producing alleles contributed significantly to a higher rate of relapse and progression (log-rank test, P = .045 and P = .027). In multivariate Cox regression models including the variables of the International Prognostic Index, the TNF/LTalpha haplotype status was found to be an independent risk factor for progression-free survival (relative risk 2.33, 95% confidence interval [1.17 to 4.64], P = . 0053) and overall survival (relative risk 1.92, 95% confidence interval [0.63 to 5.80], P = .081) of large-cell lymphoma patients. These results indicate that genetic polymorphism leading to increased TNF production influences the outcome of NHL and suggest a pathophysiological role for the genetic control of the immune response in lymphoid malignancies.

Human platelet antigen frequencies of platelet donors in the French population determined by polymerase chain reaction with sequence-specific primers

To prevent human platelet alloimmunization, Blood Transfusion Centres have to develop a strategy close to the erythrocytes' one. The first step of this strategy is to perform the HPA typing of donors with an accurate method. We applied the PCR-SSP to type 800 platelet donors in the HPA-1 and HPA-5 systems and 350 in the HPA-2 and HPA-3 ones. This study reports the human platelet antigen frequencies of four platelet-specific alloantigen systems in the French population. The results are quite similar to those currently published for Caucasian population frequencies. Low prevalences are observed for the HPA-1b, (2%), HPA-2b (0.6%) and HPA-5b (2%) groups. Furthermore, this study confirms the need to type donors and recipients in the HPA-1 system at least, in case of post-transfusion pupura and platelet refractoriness to platelet transfusion therapy.

[Contribution of dual CD13/CD14 markers in combination with CD34 for the collection of peripheral hematopoietic stem cells]

We evaluated the reliability of a flow cytometry technique for counting mononuclear cells (MNCs) in cytapheresis products. Eighty freshly-prepared samples of peripheral stem cells were studied using a dual immunolabeling technique with antibodies to CD13/CD14, and were also labeled with anti-CD34. Results of this immunophenotype determination were compared to those of the conventional method for counting MNCs under the microscope. Dual CD13/CD14 labeling was found to be a simple and reliable method for counting MNCs in the presence of immature and stimulated cells. When used in combination with CD34 labeling, the dual immunolabeling method helped improve the evaluation of the quality of peripheral stem cell grafts.

Spontaneous programmed cell death (PCD) process of lymphocytes of FIV-infected cats: cellular targets and modulation

Unstimulated lymphocytes from FIV-infected cats undergo spontaneous apoptosis in vitro as indicated by internucleosomal DNA fragmentation and hypodiploid DNA content of nuclei. Unlike what is reported in HIV-infected individuals, we observed that cell death of cat lymphocytes was inhibited by activation. Spontaneous apoptosis was reduced by the addition of cat serum and after activation by phorbol ester (PMA), superantigens (SEB, SEA), and to a lesser extent by mitogens such as concanavalin A and pokeweed mitogen. In contrast, apoptosis of lymphocytes from FIV-infected, but not from control cats was increased in the presence of calcium ionophore (ionomycin). Analysis of the phenotype of cells undergoing apoptosis revealed that cell death is not restricted to a cell subpopulation but involved all lymphocyte subsets. These data suggest that the mature lymphocytes of FIV-infected cats appear programmed to die by apoptosis unless rescued by specific agents, such as protein kinase C activators or mitogens.

Ganciclovir ophthalmic gel (Virgan; 0.15%) in the treatment of herpes simplex keratitis

PURPOSE

Ganciclovir is a broad-spectrum virustatic agent. Its efficacy and safety after ocular application have been demonstrated in studies of herpetic keratitis in rabbits. Two strengths of ganciclovir gel (0.05 and 0.15%) were compared with 3% acyclovir ointment in the treatment of superficial herpes simplex keratitis in humans.

METHODS

Two multicenter randomized clinical trials were carried out in Africa (Trial 1) and Europe (Trial 2). Sixty-seven patients (Trial 1) and 37 patients (Trial 2) from herpetic ulceration were recruited.

RESULTS

The results showed no statistically significant difference between the treatment groups, although the healing rates tended to be better in the group receiving 0.15% ganciclovir gel, with healing rates of 85% (Trial 1) and 83% (Trial 2) as compared with 72% (Trial 1) and 71% (Trial 2) in the group receiving acyclovir ointment. Local tolerance was found to be superior with the gel formulation of ganciclovir with fewer complaints of discomfort (stinging, burning) or blurred vision after application of the drug. Systemic absorption of the drug was low. No hematologic changes were detected.

CONCLUSIONS

These findings support the efficacy of ganciclovir gel in the treatment of ulcerative herpes simplex keratitis and demonstrate its superior local tolerance when compared with acyclovir ointment.

Immunophenotype of the canine transmissible venereal tumour

The canine transmissible venereal tumour is a naturally occurring contagious round-cell neoplasia which is primarily located in the mucous membrane of the external genitalia in dogs of either sex. In order to specify the controversial cytogenetic origin of this round-cell tumour, 14 cases of canine transmissible venereal tumour, formalin- or Bouin-fixed and paraffin-embedded, were subjected to extensive immunophenotypic analysis using reagents specific to a variety of cytoplasmic or surface antigens: lysozyme, ACM1 antigen, vimentin, neuron-specific enolase, glial fibrillary acidic protein, desmin, alpha smooth muscle actin, CD3, IgG, kappa and lambda light chains, and keratin. Lysozyme immunoreactivity was detected in all cases, ACM1 antigen in 11 of 14, neuron-specific enolase in 11 of 14, vimentin in 10 of 14, glial fibrillary acidic protein in 4 of 14 and desmin in 1 of 14. All the sections were negative to keratins, alpha smooth muscle actin and CD3, whereas in five cases, perivascular tumour cells contained Ig G, kappa and lambda light chains. The immunoreactivity to lysozyme and ACM1 antigen supports the hypothesis of a histiocytic immunophenotype for the canine transmissible venereal tumour.

Spontaneous programmed cell death (PCD) process of lymphocytes of FIV-infected cats: pharmacological modulation in vitro

We previously reported that unstimulated lymphocytes in culture from FIV-infected cats undergo spontaneous apoptosis in vitro as indicated by internucleosomal DNA fragmentation and hypodiploid DNA content of nuclei. Unlike what is reported in HIV-infected individuals, we observed that cell death of cat lymphocytes was inhibited by activation. Spontaneous apoptosis was reduced by the addition of cat serum, interleukins [interleukin (IL)1, Il2, IL6 and interferon-gamma (IFN gamma)] and after activation by phorbol ester [phorbol myristyl acetate (PMA)], superantigens [staphylococcal enterotoxin B (SEB), staphylococcal enterotoxin A (SEA)], and to a lesser extent by mitogens such as Concanavalin A and pokeweed mitogen, IN contrast, apoptosis of lymphocytes from FIV-infected, but not from control cats was increased in the presence of calcium ionophore (ionomycin). In this study, we studied the spontaneous programmed cell death (PCD)-inducing pathways, and the mechanisms of action of PMA, SEB and SEA. Spontaneous lymphocyte apoptosis of FIV-infected cats was inhibited by cycloheximide, ZnSO4 and N-acetyl-cystein. The preventive effect of SEB and SEA was inhibited by actinomycin, but not by inhibitors of kinases. Calyculin, an inhibitor of phosphatase, had no effect either on spontaneous apoptosis, or on the action of PMA, SEB and SEA. Ionomycin-induced apoptosis was found sensitive to PMA and cytokines. In FIV-infected cats, these data suggest that the mature lymphocytes appear programmed to die by apoptosis, unless rescued by specific agents, such as protein kinase C activators or growth factors, and that spontaneous PCD seems to be dependent of de nove protein synthesis (see effect of cycloheximide). The effects of PMA, SEB and SEA are probably mediated by de novo proteins which for PMA, undergo a phosphorylation involving serine-threonine and/or tyrosine groups. Our data suggest a clear difference between lymphocytes from FIV-infected cats and lymphocytes from HIV-infected humans, with regard to their metabolic regulations.

[Allergy and preservatives. Apropos of 3 cases of allergy to benzalkonium chloride]

BACKGROUND

Ophthalmologists are not always aware of the hypersensitising potential of benzalkonium chloride (preservative widely used in ophthalmology).

OBSERVATIONS

Hypersensitivity to benzalkonium chloride was asserted by allergologic exploration in the three cases reported. Contact allergy, a frequent phenomenon, was diagnosed in two cases. The third case represents one of the few cases described in ophthalmology of immediate hypersensitivity associated to vital risk: chemosis and angioneurotic edema is reported in a woman who had been already presented an anaphylactic shock to a quaternary ammonium family anaesthetic.

DISCUSSION

The ocular allergologic evaluation is specified. Risk to benzalkonium chloride sensitisation factors (ophthalmology, presence of benzalkonium chloride in numerous daily used products) are reviewed. The risk of severe immediate allergy is increased due to the relationship of benzalkonium chloride to other quaternary ammonium compounds.

CONCLUSION

Best risk prevention remains allergen eviction.