Efficient transport and accumulation of vitamin C in HL-60 cells depleted of glutathione

Human myeloid leukemia cells (HL-60) transport only the oxidized form of vitamin C (dehydroascorbic acid) and accumulate the vitamin in the reduced form, ascorbic acid. We performed a detailed study of the role of glutathione in the intracellular trapping/accumulation of ascorbic acid in HL-60 cells. Uptake studies using HL-60 cells depleted of glutathione by treatment with L-buthionine-(S,R) sulfoximine and diethyl maleate, revealed no changes in the cells' ability to transport dehydroascorbic acid and accumulate ascorbic acid. Similar transport and accumulation rates were obtained using HL-60 cells containing intracellular glutathione concentrations from 6 mM to 1 microM. HL-60 cells, containing as little as 5 microM glutathione, were able to accumulate up to 150 mM ascorbic acid intracellularly when incubated with dehydroascorbic acid. Glutathione was capable of reducing dehydroascorbic acid by a direct chemical reaction, but only when present in a greater than 10-fold stoichiometric excess over dehydroascorbic acid. The accumulation of ascorbic acid by HL-60 cells was strongly temperature-dependent and was very inefficient at 16 degrees C. On the other hand, the direct chemical reduction of dehydroascorbic acid by excess glutathione proceeded efficiently at temperatures of 16 degrees C. Our data indicate that glutathione-dependent reductases in HL-60 cells are not responsible for the ability of these cells to accumulate millimolar concentrations of ascorbic acid. These findings indicate that alternative enzymatic mechanisms are involved in the cellular reduction of dehydroascorbic acid.

Importance of method in the determination of syncytium-inducing phenotype of human immunodeficiency virus type 1 clinical isolates

The in vitro syncytium induction capacity of human immunodeficiency virus type 1 (HIV1) isolates is an important marker in the progression of the disease. Two methods have been widely used to determine the biological phenotype of HIV1. These two methods, the direct MT-2 assay and the supernatant assay, were compared for the detection of syncytium-inducing (SI) variants on 275 blood samples obtained from 87 HIV infected patients during a 13 month follow-up period. A SI virus was detected in 152 blood samples. In 44 blood samples, the HIV isolate was found to be SI by only one method, but was SI by both methods in another blood sample of the follow up. Among SI carriers discordant results between the methods were more frequent when the patient was on antiretroviral therapy, and a transient reversion to a non syncytium-inducing (NSI) strain confirmed by both assays was sometimes observed. The supernatant assay has a 93% sensitivity and the direct MT-2 assay has a 78% sensitivity for detection of the SI phenotype. The supernatant assay is as rapid as and less tedious than the MT-2 assay. Antiretroviral therapy could have some effects in decreasing or even suppressing the SI part of the virus population of patients with SI phenotype.

Decreased skin reactivity to codeine in patients with the acquired immunodeficiency syndrome

To evaluate the skin reactivity and the mast cell releasibility in the acquired immunodeficiency syndrome (AIDS), 24 patients with AIDS were skin tested with histamine (1 mg/ml) and codeine phosphate (0.9, 0.09, and 0.009 mg/ml), a mast cell degranulating agent. They were compared to 12 HIV-negative healthy volunteers and 16 urticaria-prone subjects. Reactivity to codeine phosphate was lower in patients with AIDS than in HIV-negative subjects. This difference in skin reactivity was the more significant when the AIDS group was compared to the urticaria-prone group. There was no correlation between the reactivity to codeine and the IgE levels. Possible explanations to the decreased skin reacting to codeine in patients with AIDS include a decrease of local mast cell density or releasibility. This suggests that a mechanism related to urticaria and involving mast cells is quite unlikely to be at the origin of the hypersensitivity reactions observed in AIDS.

Resistance to HIV-1 infection in caucasian individuals bearing mutant alleles of the CCR-5 chemokine receptor gene

HIV-1 and related viruses require co-receptors, in addition to CD4, to infect target cells. The chemokine receptor CCR-5 (ref.1) was recently demonstrated to be a co-receptor for macrophage-tropic (M-tropic) HIV-1 strains, and the orphan receptor LESTR (also called fusin) allows infection by strains adapted for growth in transformed T-cell lines (T-tropic strains). Here we show that a mutant allele of CCR-5 is present at a high frequency in caucasian populations (allele frequency, 0.092), but is absent in black populations from Western and Central Africa and Japanese populations. A 32-base-pair deletion within the coding region results in a frame shift, and generates a non-functional receptor that does not support membrane fusion or infection by macrophage- and dual-tropic HIV-1 strains. In a cohort of HIV-1 infected caucasian subjects, no individual homozygous for the mutation was found, and the frequency of heterozygotes was 35% lower than in the general population. White blood cells from an individual homozygous for the null allele were found to be highly resistant to infection by M-tropic HIV-1 viruses, confirming that CCR-5 is the major co-receptor for primary HIV-1 strains. The lower frequency of heterozygotes in seropositive patients may indicate partial resistance.

Contribution of the polymerase chain reaction to the diagnosis of tuberculous infections in children

The purpose of the study was to evaluate the contribution of polymerase chain reaction (PCR) to the diagnosis of tuberculous infection in children. Two different PCR techniques were compared to the standard bacteriological methods for the detection of Mycobacterium tuberculosis in 157 specimens obtained from the respiratory system of 51 children. Patients were classified in three groups: 12 patients with active disease (57 specimens), 12 patients with silent tuberculous infection (23 specimens) and 27 patients without tuberculosis (77 specimens). One PCR method (PCR/Ag85) used amplification of a fragment of the genes coding for the mycobacterial antigen 85 followed by hybridization of a probe specific for M. tuberculosis on the Southern blot of amplified DNA. The other PCR technique was a nested PCR (NPCR) using double amplification of a fragment of the insertion element IS6110 only present in the M. tuberculosis genome. The sensitivities of the different techniques, compared to the clinical diagnosis, were 7.0% for acid fast staining, 22.8% for culture, 24.6% for PCR/Ag85 and 44.9% for NPCR in active disease, 4.3% for culture, 8.7% for PCR/Ag85 and 28.6% for NPCR in silent tuberculous infection. The specificities were 100% for culture, 94.8% for PCR/Ag85 and 87.9% for NPCR. Among the 12 children clinically considered as having active tuberculosis, 1 had smear positive samples, 4 had at least one positive culture, 7 at least one positive PCR/Ag85 and 9 at least one NPCR positive sample. Among the 12 children having silent tuberculous infection, none had positive smears, 1 had one positive culture, 2 had at least one positive PCR/Ag85 and 5 at least one NPCR positive sample.

CONCLUSION

Our study suggests that both PCR techniques, and especially NPCR, are able to detect M. tuberculosis DNA in specimens containing few micro-organisms. PCR methods are more sensitive than culture and the results are available more quickly. Testing multiple samples from the same individual increased the sensitivity. In view of occasional false-positive results, cultures remain the gold standard to establish definitive diagnosis of primary tuberculous infection in children.

T helper type 1/T helper type 2 cytokines and T cell death: preventive effect of interleukin 12 on activation-induced and CD95 (FAS/APO-1)-mediated apoptosis of CD4+ T cells from human immunodeficiency virus-infected persons

Human immunodeficiency virus (HIV) infection leads to a progressive loss of CD4+ T helper (Th) type 1 cell-mediated immunity that is associated with defective in vitro CD4+ T cell proliferation and abnormal T cell death by apoptosis in response to T cell receptor (TCR) stimulation. Quantification of interleukin (IL)-2, interferon gamma, IL-4, IL-5, and IL-10 secretion by immunoassays, and of interferon gamma, IL-4 and IL-10 messenger RNA expression by competitive reverse transcriptase polymerase chain reaction after in vitro stimulation of the TCR revealed a similar Th1 cytokine profile in T cells from HIV-infected persons and from controls. These data indicated that the loss of CD4+ Th1 cell function in HIV-infected persons is not related to a Th1 to Th2 cytokine switch as previously proposed, but to a process of activation-induced death of CD4+ Th1 cells. Despite the absence of elevated levels of Th2 cytokines, apoptosis of CD4+ T cells, but not of CD8+ T cells, was prevented in vitro by antibodies to IL-10 or IL-4, two Th2 cytokines that downregulate Th1 cell responses, or by the addition of recombinant IL-12, a cytokine that upregulates Th1 functions. TCR-induced apoptosis of T cell hybridomas and preactivated T cells has been shown to involve the CD95 (Fas/Apo-1) molecule. CD4+ and CD8+ T cells from HIV-infected persons expressed high levels of the CD95 molecule, and, in contrast to T cells from controls, were highly sensitive to antibody-mediated CD95 ligation, which induced apoptosis in a percentage of T cells similar to that induced by TCR stimulation. As TCR-induced apoptosis, CD95-mediated apoptosis of CD4+ T cells, but not of CD8+ T cells, was prevented by the addition of recombinant IL-12. Together, these findings suggest that apoptosis of CD4+ T cells from HIV-infected persons involves an abnormal sensitivity to CD95 ligation, and to TCR stimulation in the presence of normal levels of Th2 cytokines. The preventive effect of IL-12 on both mechanisms has potential implications for the design of immunotherapy strategies aimed at the upregulation of CD4+ Th1 cell functions in AIDS.

Acute Sjögren-like syndrome as the first manifestation of a generalized CMV infection in a patient with AIDS

We report the first case of generalized cytomegalovirus (CMV) disease in an AIDS patient who presented with an acute Sjögren-like syndrome and was diagnosed by parotid gland biopsy. All symptoms disappeared after a few days of intravenous ganciclovir therapy.

Herpes simplex virus tracheitis in a patient with the acquired immunodeficiency syndrome

Herpetic tracheobronchitis and pneumonia occur basically in immunodepressed patients, but have rarely been reported in patients with the acquired immunodeficiency syndrome (AIDS). Some large reviews on pulmonary manifestations in AIDS report a small number of herpetic pulmonary infections, without determining any prevalence of this particular viral involvement. Predisposing factors are alteration of cell-mediated immunity and invasive procedures (such as endotracheal tube use) in debilitated patients. The case we report illustrates the occurrence of a herpetic tracheitis in an HIV-infected patient with severe P. carinii pneumonia, needing systemic corticotherapy and mechanical ventilation. It illustrates the risk of dissemination of herpes simplex virus (HSV) from a herpetic stomatitis to the lower respiratory tract, even after the endotracheal cannula has been removed.

Herpes simplex virus tracheitis in a patient with the acquired immunodeficiency syndrome

Herpetic tracheobronchitis and pneumonia occur basically in immunodepressed patients, but have rarely been reported in patients with the acquired immunodeficiency syndrome (AIDS). Some large reviews on pulmonary manifestations in AIDS report a small number of herpetic pulmonary infections, without determining any prevalence of this particular viral involvement. Predisposing factors are alteration of cell-mediated immunity and invasive procedures (such as endotracheal tube use) in debilitated patients. The case we report illustrates the occurrence of a herpetic tracheitis in an HIV-infected patient with severe P. carinii pneumonia, needing systemic corticotherapy and mechanical ventilation. It illustrates the risk of dissemination of herpes simplex virus (HSV) from a herpetic stomatitis to the lower respiratory tract, even after the endotracheal cannula has been removed.

Human HL-60 myeloid leukemia cells transport dehydroascorbic acid via the glucose transporters and accumulate reduced ascorbic acid

The cellular accumulation of vitamin C, a substance critical to human physiology, is mediated by transporters located at the cell membrane, and is regulated in a cell-specific manner. Neoplastic cells may have special needs for vitamin C. Therefore, we investigated the transport of vitamin C in a human myeloid leukemia cell line (HL-60). The HL-60 cells lacked the capacity to transport the reduced form of vitamin C, ascorbic acid, but they showed a remarkable ability to transport the oxidized form of vitamin C, dehydroascorbic acid (DHA). Uptake-accumulation studies indicated that the HL-60 cells accumulated ascorbic acid when provided with DHA. Kinetic analysis showed the presence of two functional activities involved in the uptake of DHA, one with low affinity and one with high affinity. Cytochalasin B and phloretin, which inhibit the passage of glucose through the facilitative glucose transporters, also inhibited the transport of DHA by HL-60 cells. Transport of DHA was completed by D- but not L-hexoses, and was sensitive to D-hexose-dependent counter transport acceleration. These data support the concept that HL-60 myeloid leukemic cells transport DHA through the facilitative hexose transporters (glucose transporters) and accumulate the reduced form of ascorbic acid.

Tumor necrosis factor and intravenous gammaglobulins in common variable immunodeficiency

Common variable immunodeficiency (CVI) patients require regular intravenous immunoglobulin substitution therapy (IVGG). We studied eight patients; four of whom had adverse reactions to IVGG, and found that those coincided with elevated tumor necrosis factor-alpha (TNF-alpha) levels during infusion. Those reactions and TNF production were abolished by switching from one IVGG preparation to another in two patients. Reappearance of adverse reactions after switching preparation was preceded by a progressive rise in peak TNF levels in one patient.

Evaluation of two staging systems for HIV infection for use in developing countries

OBJECTIVE

To evaluate the clinical axis of the World Health Organization (WHO) clinical staging system and the modified WHO staging system proposed by Montaner et al. using the lymphocyte strata > 1500, 1500-1000 and < 1000 cells x 10(6)/l.

DESIGN

Cross-sectional study.

PATIENTS

Four hundred and fifteen consecutive patients with HIV infection attending three HIV reference centres in Belgium.

METHODS

Absolute CD4 lymphocyte counts were compared between stages within the two staging systems.

RESULTS

Median CD4 lymphocyte counts decreased with increasing stage of disease in both staging systems. Differences in median CD4 lymphocyte counts between stages of each staging system were statistically significant (Kruskal-Wallis one-way analysis of variance, P < 0.001). The WHO clinical stage 1 and the modified WHO stage I had positive predictive values of 56 and 58%, respectively, for identifying patients with CD4 lymphocyte levels > 500 cells x 10(6)/l. The WHO clinical stage 4 and the modified WHO stage IV had positive predictive values of 79 and 80%, respectively, for identifying patients with CD4 lymphocyte levels < 200 cells x 10(6)/l.

CONCLUSIONS

The WHO clinical staging system or a modified version of this system using lymphocytes stratification may be a good alternative in developing countries to the CD4 lymphocyte count-based HIV staging system used in the developed world. Cohort studies in developing countries are needed to assess their prognostic value.

Glutathione depletion in chronic lymphocytic leukemia B lymphocytes

Glutathione (GSH) content may be the major determinant of a cell's sensitivity to cytotoxic alkylating agents. In the present study, the GSH concentration was determined in lymphocytes isolated from the blood of normal subjects and patients with chronic lymphocytic leukemia (CLL). Comparable levels were found in both types of cells. Incubation for 20 hours led to a decrease in GSH to 51% of baseline values in CLL B cells. Under the same conditions, normal B- or T-lymphocyte GSH content remained constant. GSH depletion was shown to be a characteristic of the B-CLL B lymphocyte. It was not found in the T cells of patients with B-CLL or in cells from patients with T-CLL. Chlorambucil (CLB) contributes to the decrease in GSH in B-CLL lymphocytes; after incubation with the drug, lower levels of GSH were found than in the normal B or T lymphocytes, B-CLL T cells, or T-CLL (CD4 or CD8) cells. GSH depletion of CLL B lymphocytes may be related to the greater therapeutic efficacy of CLB in B-CLL than in T-CLL.

The humoral immune response after BCG vaccination: an immunoblotting study using two purified antigens

The specific IgG response induced by BCG vaccination was investigated in 27 adults using two purified BCG antigens in a dot immunoblotting assay. The reflectance values increased significantly after vaccination when P64 but not when P32 was used as the antigen. The values measured after vaccination were compared with those obtained when testing sera from patients with tuberculosis. We observed that the level of anti-P64 IgG reached after BCG immunization was high enough to preclude a serological differential diagnosis with tuberculosis.