Vinblastine, bleomycin, and methotrexate chemotherapy plus extended-field radiotherapy in early, favorably presenting, clinically staged Hodgkin's patients: the Gruppo Italiano per lo Studio dei Linfomi Experience.

PURPOSE: To ascertain whether vinblastine, bleomycin, and methotrexate (VBM) (CT) combined with extended-field radiotherapy (EF RT) is effective enough to spare laparotomy in early, favorably presenting Hodgkin's disease (HD) patients. PATIENTS AND METHODS: Fifty patients with clinical stage IA or IIA HD with favorable histology and no bulky masses entered a prospective multicenter study started in January 1988. The median follow-up time was 38 months. RESULTS: All patients achieved a complete remission (CR). Five relapsed after 3 to 40 months and underwent successful salvage therapy. The actuarial remission rate was 0.89% at 3 years and 0.82% at 5 years. Two patients died in CR: one of severe pulmonary toxicity, the other of a second neoplasia (adenocarcinoma of the lung), 2 and 43 months after the end of therapy, respectively. The hematologic toxicity recorded during VBM CT was mild on the whole. Major toxicity was represented by pulmonary side effects and neurologic symptoms. Multiple regression analysis demonstrated that pulmonary toxicity was significantly related only to the amount of RT delivered to the mediastinum and not to the relative dose of bleomycin, to the dose-intensities of the three drugs in the regimen, or to patient age or sex. The same statistical technique showed that the only clinical factor related to grade of neurotoxicity was vinblastine dosage. CONCLUSION: VBM CT combined with EF RT is an effective treatment for early, clinically staged, favorable HD patients. However, the toxicity of this combination suggests that certain modifications should be evaluated.

Ligand activation of nerve growth factor receptor TrkA protects monocytes from apoptosis.

Nerve growth factor (NGF) receptors are expressed in different cell types outside the nervous system, and increasing evidence indicates that NGF can act as a regulatory molecule during inflammatory and immune responses. In this study, we show that triggering of the high-affinity NGF receptor TrkA with agonists protects monocytes from apoptosis induced by gliotoxin or UVB radiation. TrkA stimulation up-regulates the expression of the anti-apoptotic Bcl-2 family members, Bcl-2, Bcl-XL, and Bfl-1. On the other hand, TrkA stimulation does not change the expression of MHC, CD80, CD86, CD40, and CD54 molecules, nor the antigen-presenting function of monocytes. In addition, during in vitro monocyte to dendritic cell differentiation TrkA expression is progressively lost, suggesting that NGF selectively affects monocyte but not dendritic cell survival.

Defective expression of interferon-gamma, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha, and interleukin-6 in activated peripheral blood lymphocytes from glioma patients.

The ability of a mannoprotein antigen from Candida albicans (MP) or interleukin-2 (IL-2) to induce cytokines in cultures of peripheral blood mononuclear cells (PBMC) of glioma patients and healthy controls was evaluated by mRNA expression and by protein secretion. The subjects studied were all responsive to both MP and IL-2, as assayed by lymphoproliferation of PBMC cultures. In control subjects, MP and IL-2 were strong inducers of IFN-gamma, IL-1 beta, TNF-alpha, and GM-CSF mRNA expression, but only MP was able to induce considerable levels of IL-6 and IL-2 mRNA expression. In MP-activated PBMC from glioma subjects, a highly defective IFN-gamma, together with a significant reduction in TNF-alpha and GM-CSF mRNA expression, was observed. This impairment was paralleled by a decreased accumulation of IL-6 and IL-2 mRNA. The pattern of cytokine mRNAs in IL-2-activated PBMC of glioma patients confirmed the impairment of IFN-gamma mRNA expression paralleled by a reduction in IL-6, TNF-alpha and GM-CSF mRNA, compared with healthy subjects. Coherently, in PBMC cultures from glioma patients, there was a clear-cut decrease in the secretion of IL-6 and TNF-alpha and especially of IFN-gamma compared with healthy controls. No or very low levels of IL-4, IL-10, and TGF-beta 2 mRNA expression were detected in PBMC cultures of both glioma and control populations, irrespective of the activation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell-mediated and antibody responses to Bordetella pertussis antigens in children vaccinated with acellular or whole-cell pertussis vaccines. The Progetto Pertosse-CMI Working Group.

OBJECTIVE: To examine induction and persistence of cell-mediated immunity (CMI) and antibody responses to Bordetella pertussis antigens in infants receiving antipertussis vaccines. DESIGN AND SETTING: A randomized, blinded study of 142 children receiving acellular pertussis vaccines combined with diphtheria-tetanus toxoids (DTaP) (DTaP manufactured by SmithKline Beecham [DTaP-SB], Rixensart, Belgium, and DTaP manufactured by Chiron Biocin [DTaP-CB], Siena, Italy), or a whole-cell pertussis vaccine (DTwP) (Connaught Laboratories Inc, Swiftwater, Pa), or a diphtheria-tetanus (DT) (Chiron Biocine) only vaccine. Three doses of each vaccine were given at 2, 4, and 6 months of age, and CMI and antibody responses were evaluated before and at 1 and 14 months after vaccination. METHODS AND MAIN OUTCOME MEASURES: Cell-mediated immunity was assessed by proliferation of peripheral blood mononuclear cells stimulated in vitro by B pertussis antigens (pertussis toxin, filamentous hemagglutinin, and pertactin). Antibody titers against pertussis toxin, filamentous hemagglutinin, and pertactin were determined by a standardized enzyme-linked immunosorbent assay. RESULTS: A CMI-positive response to at least 1 B pertussis antigen at 1 or both postvaccination assays was detected in 46%, 55%, and 83% of DTwP, DTaP-SB, and DTaP-CB vaccine recipients, respectively. Frequency of CMI response to individual antigens ranged from less than 4.9% against pertussis toxin in DTwP recipients to 52% against pertactin in DTaP-CB recipients. The postvaccination responses measured at 14 months equalled, or had increased frequency or intensity, that of the 1-month postvaccination responses. Elevated antibody titers against the 3 antigens were present in all DTaP recipients 1 month after vaccination and were higher in CMI-positive children than in CMI-negative children. They fell, however, to low, if not negligible, levels 14 months after vaccination. CONCLUSIONS: Acellular pertussis vaccines were better inducers of CMI response than the whole-cell vaccine, particularly against pertussis toxin. Once acquired, CMI persisted, in contrast with the rapid antibody decline. Thus, CMI responses could be a useful adjunct to serology in the evaluation of pertussis vaccine immunogenicity and a better correlate of long-term immunity to B pertussis than antibody titers.

Mannoproteins from Candida albicans elicit a Th-type-1 cytokine profile in human Candida specific long-term T cell cultures.

Since T lymphocytes are active producers of regulatory cytokines, long-term T cell cultures (LTTC) specific for a major mannoproteic antigen (MP) of Candida albicans from peripheral blood mononuclear cells (PBMC) of healthy donors were generated and their cytokine profile studied. LTTC consisted of an expanded CD3CD4 T-helper (Th) populations, with a high proportion of CD45R0 T memory cells. Stimulation of LTTC by MP induced a Th-1 type cytokine profile, as indicated by the presence of IFN-gamma and the absence of IL-5 (both as mRNA and protein) in cell cultures and supernatants. These results suggest a predominant Th1 response elicited by C. albicans mannoprotein antigen in human PBMC.

Pefloxacin in the antibacterial treatment of immunodepressed patients.

Pefloxacin 800 to 1200 mg daily was given for 3 to 20 days, orally or intravenously, to 84 immunocompromised patients. Five patients dropped out because of side effects and 2 for other causes. Treatment efficacy was evaluated in 77 patients, 43 men and 34 women, aged 18 to 80 years. Immunodepression resulted from malignancy in 46 patients, LAS/ARC or AIDS in 28, and from unknown causes in 3. Fifty-eight patients had documented infections (respiratory-tract infections 29, urinary-tract infections 13, septicemia 10, other 6) and 19 had a fever of unknown origin (FUO). Cure or significant improvement of symptoms was achieved in 81% of patients with documented infections and in 74% of patients with FUO. Side effects (mainly gastrointestinal disturbances and skin rash) occurred in 7 patients (8.2%), including dropouts. These results suggest that pefloxacin may be useful for the antibacterial treatment of immunodepressed patients.

Clinical relevance of immunocytochemical detection of multidrug-resistance-associated P-glycoprotein in hematologic malignancies.

P-glycoprotein (P-170) is the phenotypic marker of tumoral cells that show the phenomenon of multidrug resistance (MDR). Using an immunocytochemical approach, we employed the monoclonal antibody C219 (which recognizes an epitope of such a glycoprotein) to evaluate in cytologic samples the expression of P-170 on neoplastic cells from 52 patients affected by different hematologic malignancies and its eventual correlation to clinical outcome. Longitudinal studies were also performed in 14 patients. Results obtained demonstrated that a) the so-called "MDR phenotype" may be heterogeneously represented (from less than 1 to 100% of positive cells) in hemopoietic tumors at diagnosis (without exposure to pharmacologic agents), as well as during the course of the disease, although a more substantial presence of P-170 occurred in treated patients. There was no correlation between neoplastic kinetic activity (such as expression of Ki 67 recognized nuclear proliferation-associated antigen) and P-170-positive cells. b) Percentage of positive cells as well as intensity of staining seemed to be important in determining MDR; in general, there was a strong correlation between expression of P-170 in more than 20% of neoplastic cells and a lack of response to chemotherapy. However, some false-positive and false-negative cases were observed. c) The detection of scattered P-170-positive cells may predict a pharmacologic selection of intrinsic or mutant-resistant clones.

Acellular vaccines induce cell-mediated immunity to Bordetella pertussis antigens in infants undergoing primary vaccination against pertussis.

The induction of cell-mediated immunity (CMI) to Bordetella pertussis antigens (whole, heat-inactivated bacterial cells [BPC], pertussis toxin [PT], filamentous haemagglutinin [FHA], pertactin [PRN]) was assessed by a lymphoproliferation assay in vitro in a cohort of children enrolled in a randomized clinical trial of pertussis vaccines efficacy in Italy. Four vaccination groups were compared: children receiving acellular pertussis (aP) vaccines from SmithKline Beecham (SB) or Chiron Biocine (CB) or whole-cell vaccine (wP) from Connaught, each combined with diphtheria and tetanus toxoids (DT), or a DT vaccine only. When the purified antigens were used, statistically significant differences in CMI responses were observed between pre- and post-vaccination samples. In particular, CMI responses to FHA and PRN were detected in the majority of both aP vaccines recipients, whereas DTwP-recipients were CMI-positive in a much lower proportion. Clear-cut differences in PT responses were detected between DTwP and DTaP vaccine recipients, in favour of the latter. These differences were maintained up to 24 months after completion of the primary vaccination schedule. Thus, CMI responses could be a useful adjunct to serology in studying the immune responses to pertussis vaccines.

Vaccine- and antigen-dependent type 1 and type 2 cytokine induction after primary vaccination of infants with whole-cell or acellular pertussis vaccines.

Cytokine profiles were examined 1 month after primary vaccination of infants with a whole-cell pertussis vaccine (wP) (Connaught) or either of two acellular pertussis vaccines, aP-Chiron Biocine (aP-CB) or aP-SmithKline Beecham (aP-SB), each combined with diphtheria-tetanus toxoids (DT), in Bordetella pertussis antigen-stimulated or unstimulated peripheral blood mononuclear cells (PBMC). Pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) were used as antigens, and the children were defined as responsive when their PBMC proliferated in response to these antigens. The controls were either children who received only DT or children who received pertussis vaccine but whose PBMC did not proliferate upon stimulation with B. pertussis antigens (unresponsive children). Antigen-stimulated PBMC of responsive wP recipients were characterized by an elevated production of T-helper-cell type 1 cytokines gamma interferon (IFN-gamma) and interleukin 2 (IL-2), low to minimal production of IL-5, and no production of IL-4. The PBMC of aP vaccine-responsive recipients showed, in addition to the elevated IFN-gamma production, a consistent, antigen-dependent production of type 2 cytokines (IL-4 and IL-5), with PRN being the most and PT being the least effective antigen. Type 2 cytokine induction was more pronounced in aP-SB than in aP-CB recipients, as shown by the presence of IL-4 mRNA transcripts and higher IL-5 production in the former (161.6 +/- 36 and 47.9 +/- 44 pg/ml [mean +/- standard error for five subjects each], respectively, after PRN stimulation). Appreciable, antigen-unstimulated (constitutive) IFN-gamma production was also detected in PBMC cultures of all vaccinees. However, this spontaneous IFN-gamma production was, in most vaccinees, significantly lower than the antigen-driven cytokine production. In contrast, no constitutive type 2 cytokine production was ever observed in any vaccine group. PBMC from the two control groups (either DT or pertussis vaccine recipients) did not show any type 2 cytokine production, while IFN-gamma production was comparable in both antigen-stimulated and unstimulated conditions. Absence of type 2 cytokines and low levels of constitutive IFN-gamma production were also seen in prevaccination children. Thus, pertussis vaccines induce in infants a basically type 1 cytokine profile, which is, however, accompanied by some production of type 2 cytokines. The latter are more expressed by aP-SB than by aP-CB recipients, and with PRN than with other antigens, and they are minimally expressed in wP recipients and with PT as antigen. Our data also highlight a constitutive IFN-gamma production in infancy, which might reflect natural immunization and/or the burden of concomitant vaccinations and which may have an impact on T-helper-cell cytokine pattern polarization consequent to pertussis vaccination.

Cell-mediated immune response of healthy adults to Bordetella pertussis vaccine antigens.

Cell-mediated immunity (CMI) to Bordetella pertussis and acellular pertussis vaccine constituents (pertussis toxin, pertactin, and filamentous hemagglutinin) were studied in peripheral blood mononuclear cells (PBMC) and T cell cultures from healthy adults with no record of vaccination against, or history of, pertussis. Similarly to stimulation with common recall antigens, PBMC proliferation was induced in 80%-100% of the cultures, depending on the specific B. pertussis stimulant. Proliferation did not occur when antigen-presenting cells were ablated by chemical or physical methods or with naive cord blood lymphocytes. B. pertussis antigen stimulation resulted in a preferential induction of type 1 cytokine profile, as shown by interferon-gamma and interleukin-2 (but no interleukin-4 or interleukin-5) gene transcripts and actual cytokine production by T cells. The data suggest that most healthy adults are repeatedly exposed to B. pertussis, with natural acquisition of antigen-specific CMI and a putatively protective type 1 cytokine pattern.

Regulatory activity of autocrine IL-10 on dendritic cell functions.

IL-10 is a critical cytokine that blocks the maturation of dendritic cells (DCs), but the relevance of autocrine IL-10 on DC functions has not been investigated. In this study, we found that immature monocyte-derived DCs released low but sizeable amounts of IL-10. After stimulation with bacteria, LPS, lipoteichoic acid, or soluble CD40 ligand, DCs secreted high levels of IL-10. Addition of an anti-IL-10-neutralizing Ab to immature DCs as well as to soluble CD40 ligand- or LPS-maturing DCs led to enhanced expression of surface CD83, CD80, CD86, and MHC molecules and markedly augmented release of TNF-alpha and IL-12, but diminished IL-10 mRNA expression. Moreover, DCs treated with anti-IL-10 Ab showed an increased capacity to activate allogeneic T cells and primed naive T cells to a more prominent Th1 polarization. DC maturation and IL-10 neutralization were associated with enhanced accumulation of the IL-10 receptor binding chain (IL-10R1) mRNA and intracellular IL-10R1 protein. In contrast, surface IL-10R1 and IL-10 binding activity diminished in mature DCs. These results indicate that autocrine IL-10 prevents spontaneous maturation of DCs in vitro, limits LPS- and CD40-mediated maturation, and increases IL-10 production by DCs. Moreover, IL-10R expression appears to be regulated by both transcriptional and posttranscriptional mechanisms. Endogenous IL-10 and IL-10R can be relevant targets for the manipulation of DC functions.

Extracellular ATP induces a distorted maturation of dendritic cells and inhibits their capacity to initiate Th1 responses.

Dendritic cells (DCs) express functional purinergic receptors, but the effects of purine nucleotides on DC functions have been marginally investigated. In this study, we report on the ability of micromolar concentrations of ATP to affect the maturation and Ag-presenting function of monocyte-derived DCs in vitro. Chronic stimulation (24 h) of DCs with low, noncytotoxic ATP doses increased membrane expression of CD54, CD80, CD86, and CD83, slightly reduced the endocytic activity of DCs, and augmented their capacity to promote proliferation of allogeneic naive T lymphocytes. Moreover, ATP enhanced LPS- and soluble CD40 ligand-induced CD54, CD86, and CD83 expression. On the other hand, ATP markedly and dose-dependently inhibited LPS- and soluble CD40 ligand-dependent production of IL-1alpha, IL-1beta, TNF-alpha, IL-6, and IL-12, whereas IL-1 receptor antagonist and IL-10 production was not affected. As a result, T cell lines generated from allogeneic naive CD45RA(+) T cells primed with DCs matured in the presence of ATP produced lower amounts of IFN-gamma and higher levels of IL-4, IL-5, and IL-10 compared with T cell lines obtained with LPS-stimulated DCs. ATP inhibition of TNF-alpha and IL-12 production by mature DCs was not mediated by PGs or elevation of intracellular cAMP and did not require ATP degradation. The inability of UTP and the similar potency of ADP to reproduce ATP effects indicated that ATP could function through the P2X receptor family. These results suggest that extracellular ATP may serve as an important regulatory signal to dampen IL-12 production by DCs and thus prevent exaggerated and harmful immune responses.

CD38 ligation induces discrete cytokine mRNA expression in human cultured lymphocytes.

Human CD38 is a surface glycoprotein expressed by different immuno-competent cells such as immature and activated lymphocytes, plasma cells and natural killer cells. It has recently been reported that the CD38 molecule exerts adenosine diphosphate ribosyl cyclase activity and is associated with distinct transmembrane signaling molecules. This study reports that ligation of CD38 by specific monoclonal antibodies (mAb) induces multiple cytokine mRNA expression in cultured peripheral blood mononuclear cells (PBMC). The mRNA for tumor necrosis factor-alpha, interleukin (IL)-1 beta, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-12 were always detected, whereas interferon-gamma and IL-10 mRNA expression were seen in most, but not all PBMC cultures. Low levels of IL-2, IL-4 and IL-5 mRNA were also found. The key observation of this work is that CD38 ligation in PBMC induces a large spectrum of cytokines, many of which overlap with those induced via CD3 activation. The main differences between CD38 and CD3 activation are the low to undetectable levels of IL-2 mRNA, and the sustained IL-1 beta and IL-6 mRNA accumulation found in PBMC cultures following treatment with anti-CD38 mAb. Furthermore, PBMC proliferation was not found to be a prerequisite for CD38-mediated cytokine induction. Together, these results suggest that human CD38 activates a signaling pathway which leads to the induction of a discrete array of cytokines, and that this pathway only partially overlaps with that controlled by T cell receptor CD3.

Secretion of IFN-gamma, IL-6, granulocyte-macrophage colony-stimulating factor and IL-10 cytokines after activation of human purified T lymphocytes upon CD38 ligation.

Human CD38, a surface glycoprotein expressed by different immunocompetent cells, is associated with distinct transmembrane signaling molecules and plays a key role in the synthesis of cyclic ADP-ribose, a calcium-mobilizing compound. This study reports that CD38 ligation by specific monoclonal antibodies (mAb) in purified peripheral blood T cells is followed by secretion of discrete cytokines. IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), IFN-gamma, and IL-10 mRNA expression were constant findings. Low levels of IL-2 mRNA were also detected in CD38-activated T lymphocyte cultures of all subjects studied. Low levels of IL-4 and IL-5 mRNA were detected in the majority of CD38-activated T cultures. Moreover, CD38 mediated cytokine induction does not require T cell proliferation or the addition of antigen presenting cells. In conclusion, human CD38 runs an activation pathway in purified T cells which operates through the induction of a cytokine profile shared by Th1 or Th2 cells.

Cell-mediated immune responses in four-year-old children after primary immunization with acellular pertussis vaccines.

Cell-mediated immune (CMI) responses to Bordetella pertussis antigens (pertussis toxin [PT], pertactin [PRN], and filamentous hemagglutinin [FHA]) were assessed in 48-month-old recipients of acellular pertussis [aP] vaccines (either from Chiron-Biocine [aP-CB] or from SmithKline Beecham [aP-SB]) and compared to CMI responses to the same antigens at 7 months of age, i.e., 1 month after completion of the primary immunization cycle. None of the children enrolled in this study received any booster of pertussis vaccines or was affected by pertussis during the whole follow-up period. Overall, around 75% of 4-year-old children showed a CMI-positive response to at least one B. pertussis antigen, independently of the type of aP vaccine received, and the proportion of CMI responders were at least equal at 48 and 7 months of age. However, longitudinal examination of individual responses showed that from 20 (against PT) to 37% (against FHA) of CMI responders after primary immunization became negative at 48 months of age. This loss was more than compensated for by conversion to positive CMI responses, ranging from 36% against FHA to 69% against PRN, in other children who were CMI negative at 7 months of age. In 60 to 80% of these CMI converters, a lack of decline or even marked elevation of antibody (Ab) titers against B. pertussis antigens also occurred between 20 and 48 months of age. In particular, the frequency of seropositivity to PRN and FHA (but not to PT) was roughly three times higher in CMI converters than in nonconverters. The acquisition of CMI response to B. pertussis antigens in 48-month-old children was not associated with a greater frequency of coughing episodes lasting >/=7 days and was characterized by a prevalent type 1 cytokine profile, with high gamma interferon and low or no production of interleukin-5, reminiscent of cytokine patterns following immunization with whole-cell pertussis vaccine or natural infection. Our data imply that vaccination-induced systemic CMI may wane by 4 years of age but may be acquired or naturally boosted by symptomless or minor clinical infection by B. pertussis. This might explain, at least in part, the persistence of protection against typical pertussis in aP vaccine recipients despite a substantial waning of both Ab and CMI responses induced by the primary immunization.

Increased CD10/TdT positive cells in the bone marrow of an infant with immune thrombocytopenia.

We describe the case of an infant with immune thrombocytopenia whose bone marrow showed an increased percentage of CD10/TdT-positive lymphoid cells that resembled the onset of an acute lymphoproliferative disorder. Genotypic analysis of bone marrow, however, failed to reveal the malignant origin of these B cell precursors. After 8 months of follow-up, the child is alive and well, and shows a chronic form of ITP. Although a relation between this B cell proliferation and the onset of ITP cannot be excluded, it is important to consider this atypical pattern as a benign hematologic condition.

Significance and limits of cerebrospinal fluid beta-2-microglobulin measurement in course of acute lymphoblastic leukemia.

Cerebrospinal fluid beta-2-microglobulin (CSF-beta 2m) was measured longitudinally in 48 patients affected by acute lymphoblastic leukemia (ALL). Thirteen developed a central nervous system (CNS) involvement during the course of the disease; although moderately higher mean CSF-beta 2m levels were found in these subjects, no significant statistical differences were observed in comparison with patients without this complication and compared with the control group. No correlations were found between beta 2m and other biochemical parameters in CSF. Furthermore, CSF-beta 2m levels appeared to be influenced by previous combined chemoradiotherapeutic treatment for CNS prophylaxis, presence of meningeal non-neoplastic infiltrates, patients' ages, amount of CSF blasts, and their immunological phenotype. In particular, only clearly B-committed leukemic cells, when tested, showed a strong surface expression of beta 2m, as demonstrated by immunocytochemical detection of this protein on cell membrane. However, in specific cases, CSF beta 2m measurement and CSF/serum beta 2m ratio were helpful in diagnosing and monitoring isolated CNS disease. Such findings suggest that CSF-beta 2m assay may be a useful tool in the management of CNS involvement in the course of ALL in only selected patients, as several factors can modify the outcome.

Functional topography of discrete domains of human CD38.

In addition to its catalytic activities as ecto-NAD+ glycohydrolase (NADase), CD38 displays the ability to transduce signals of biological relevance. Indeed, ligation of CD38 on peripheral blood mononuclear cells (PBMC) by agonistic monoclonal antibodies (mAbs) is followed by the transcription and secretion of a vast array of regulatory cytokines. The present work addresses the issue of whether the signals leading to calcium (Ca2+) mobilization, lymphocyte proliferation and release of cytokines is dependent on the epitopes recognized by the individual mAbs. Competition binding analysis identifies two families of mAbs, namely IB4, IB6 and AT2 on one side and OKT10, SUN-4B7 and AT1 on the other. Each mAb family binds epitopes that are completely or partially common. However, the functional activities of the CD38 molecule can not be simply attributed to the epitopes engaged: for instance, IB4 and OKT10 mAbs, which bind different epitopes, perform as agonistic mAbs in inducing PBMC proliferation and interferon (IFN)-gamma secretion. SUN-4B7 yields intermediate effects, whereas IB6, AT1 and AT2 mAbs are totally ineffective. The effects mediated by IB4 and OKT10 mAbs are apparent in 80% of the healthy individuals studied, whereas the effects of SUN-4B7 mAb operate only in 25% of the donors. Interleukin (IL)-6 secretion was observed in all individuals analyzed, irrespective of the epitopes triggered and of mAbs used to ligate the CD38 molecule. In addition, IB4 is the only mAb able to induce significant intracellular Ca2+ fluxes.

The P2 purinergic receptors of human dendritic cells: identification and coupling to cytokine release.

We investigated the expression of purinoceptors in human dendritic cells, providing functional, pharmacological, and biochemical evidence that immature and mature cells express P2Y and P2X subtypes, coupled to increase in the intracellular Ca(2+), membrane depolarization, and secretion of inflammatory cytokines. The ATP-activated Ca(2+) change was biphasic, with a fast release from intracellular stores and a delayed influx across the plasma membrane. A prolonged exposure to ATP was toxic to dendritic cells that swelled, lost typical dendrites, became phase lucent, detached from the substrate, and eventually died. These changes were highly suggestive of expression of the cytotoxic receptor P2X(7), as confirmed by ability of dendritic cells to become permeant to membrane impermeant dyes such as Lucifer yellow or ethidium bromide. The P2X(7) receptor ligand 2',3'-(4-benzoylbenzoyl)-ATP was a better agonist then ATP for Ca(2+) increase and plasma membrane depolarization. Oxidized ATP, a covalent blocker of P2X receptors, and the selective P2X(7) antagonist KN-62 inhibited both permeabilization and Ca(2+) changes induced by ATP. The following purinoceptors were expressed by immature and mature dendritic cells: P2Y(1), P2Y(2), P2Y(5), P2Y(11) and P2X(1), P2X(4), P2X(7). Finally, stimulation of LPS-matured cells with ATP triggered release of IL-1 beta and TNF-alpha. Purinoceptors may provide a new avenue to modulation of dendritic cells function.