Health-state utilities in long-term advanced melanoma survivors comparable with the general population

BACKGROUND

Checkpoint inhibitors have been shown to substantially improve the survival of patients with advanced melanoma. With this growing group of survivors treated with immunotherapies, assessing their health-state utilities is essential and can be used for the calculation of quality-adjusted life years and for cost-effectiveness analyses. Therefore, we evaluated the health-state utilities in long-term advanced melanoma survivors.

METHODS

Health-state utilities were evaluated in a cohort of advanced melanoma survivors 24-36 months (N = 37) and 36-plus months (N = 47) post-ipilimumab monotherapy. In addition, the health-state utilities of the 24-36 months survivor group were assessed longitudinally, and utilities of the combined survival groups (N = 84) were compared with a matched control population (N = 168). The EQ-5D was used to generate health-state utility values, and quality-of-life questionnaires were used to establish correlations and influencing factors of utility scores.

RESULTS

Health-state utility scores were similar between the 24-36 months'- and the 36-plus months' survival group (0.81 vs 0.86; p = .22). In survivors, lower utility scores were associated with symptoms of depression (β = - .82, p = .022) and fatigue burden (β = - .29, p = .007). Utility scores did not significantly change after 24-36 months of survival, and the utilities of survivors were comparable to the matched control population (0.84 vs 0.87; p = .07).

DISCUSSION

Our results show that long-term advanced melanoma survivors treated with ipilimumab monotherapy experience relatively stable and high health-state utility scores.

Health-related quality of life of long-term advanced melanoma survivors treated with anti-CTLA-4 immune checkpoint inhibition compared to matched controls

BACKGROUND

Checkpoint inhibitors have changed overall survival for patients with advanced melanoma. However, there is a lack of data on health-related quality of life (HRQoL) of long-term advanced melanoma survivors, years after treatment. Therefore, we evaluated HRQoL in long-term advanced melanoma survivors and compared the study outcomes with matched controls without cancer.

MATERIAL AND METHODS

Ipilimumab-treated advanced melanoma survivors without evidence of disease and without subsequent systemic therapy for a minimum of two years following last administration of ipilimumab were eligible for this study. The European Organization for Research and Treatment of Cancer quality of life questionnaire Core 30 (EORTC QLQ-C30), the Multidimensional Fatigue Inventory (MFI), the Hospital Anxiety and Depression Scale (HADS), and the Functional Assessment of Cancer Therapy-Melanoma questionnaire (FACT-M) were administered. Controls were individually matched for age, gender, and educational status. Outcomes of survivors and controls were compared using generalized estimating equations, and differences were interpreted as clinically relevant according to published guidelines.

RESULTS

A total of 89 survivors and 265 controls were analyzed in this study. After a median follow-up of 39 (range, 17-121) months, survivors scored significantly lower on physical (83.7 vs. 89.8, difference (diff) = -5.80, p=.005), role (83.5 vs. 90, diff = -5.97, p=.02), cognitive (83.7 vs. 91.9, diff = -8.05, p=.001), and social functioning (86.5 vs. 95.1, diff = -8.49, p= <.001) and had a higher symptom burden of fatigue (23.0 vs. 15.5, diff = 7.48, p=.004), dyspnea (13.3 vs. 6.7, diff = 6.47 p=.02), diarrhea (7.9 vs. 4.0, diff = 3.78, p=.04), and financial impact (10.5 vs. 2.5, diff = 8.07, p=.001) than matched controls. Group differences were indicated as clinically relevant.

DISCUSSION

Compared to matched controls, long-term advanced melanoma survivors had overall worse functioning scores, more physical symptoms, and financial difficulties. These data may contribute to the development of appropriate survivorship care.

(Neo)adjuvant systemic therapy for melanoma

Surgery still is the cornerstone of treatment for patients with stage II and III melanoma, but despite great efforts to gain or preserve locoregional control with excision of the primary tumour, satellites, intransits, sentinel node biopsy and lymphadenectomy, surgery alone does not seem to improve survival any further. Prognosis for patients with high risk melanoma remains poor with 5-year survival rates of 40 to 80%. Only interferon-2b has been approved as adjuvant therapy since 1995, but clinical integration is low considering the high risk-benefit ratio. In recent years systemic targeted- and immunotherapy have proven to be beneficial in advanced melanoma and could be a promising strategy for (neo)adjuvant treatment of patients with resectable high risk melanomas as well. Randomised, placebo- controlled phase III trials on adjuvant systemic targeted- and immunotherapy are currently being performed using new agents like ipilimumab, pembrolizumab, nivolumab, vemurafenib and dabrafenib plus trametinib. In this article we review the literature on currently known adjuvant therapies and currently ongoing trials of (neo)adjuvant therapies in high risk melanomas.

Choi response criteria for prediction of clinical outcome in patients with metastatic renal cell cancer treated with sunitinib

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Background: Sunitinib (SU) has been approved for the treatment of metastatic renal cell cancer (mRCC). Since SU can induce extensive necrosis, RECIST may be inappropriate for tumor response evaluation. We evaluated whether the new Choi criteria (J Clin Oncol. 2007;25:1753–1759) are of additional value to predict outcome in mRCC patients (pts) treated with SU. Methods: 56 mRCC pts treated with SU were included. Imaging data consisted of thoracic and abdominal helical CT scans at baseline, after a median of 2 months and were repeated during treatment. For Choi criteria the longest diameter was ≥15 mm. Density of these lesions was determined in Hounsfield units. According to Choi criteria partial response (PR) was defined as ≥10% decrease in size or ≥15% decrease in density, while progressive disease (PD) was defined as ≥10% increase in size without meeting PR criteria by density. Progression-free survival (PFS) and overall survival (OS) were calculated according to Kaplan-Meier. Log rank test was used to test the statistical difference between survival curves. Results: For RECIST and Choi criteria, respectively, 230 and 156 tumor lesions were eligible. At first evaluation, according to RECIST 7 pts had PR, 39 stable disease (SD), and 10 PD, while according to Choi criteria 33 pts had PR, 8 SD and 15 PD. The median tumor density decreased significantly (Wilcoxon Signed Ranks test, p ≤ 0.001). At first evaluation in patients with PR, Choi criteria had a significantly better predictive value for PFS and OS (p < 0.001 and p < 0.001, respectively) than RECIST (p = 0.384 and p = 0.392, respectively). When best response during treatment was analyzed according to RECIST, the predictive value of RECIST increased for both PFS and OS (p = 0.004 and p = 0.002, respectively). For clinical benefit (PR+SD), the predictive value of RECIST and Choi criteria for PFS and OS were comparable (both p < 0.001). Conclusions: Choi criteria can be easily applied on contrast-enhanced CT scans. RECIST and Choi criteria have similar predictive value for outcome in pts with clinical benefit. Choi criteria, however, are more useful to early define a large pt population with favourable clinical outcome.

[Table: see text]

Biochemical and immunologic correlates of clinical response in a combination trial of the GM-CSF-gene transduced allogeneic prostate cancer immunotherapy and ipilimumab in patients with metastatic hormone-refractory prostate cancer (mHRPC)

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Background: A Phase 1 trial is underway to study the GM-CSF-secreting immunotherapy for prostate cancer (GVAX immunotherapy [GVAX IT]) and ipilimumab (ipi) in mHRPC patients (pts). Methods: Twelve pts were treated for 24 weeks (wks) with bi-weekly intradermal injections of GVAX IT and monthly Ipi. Pts were enrolled in cohorts of 3; each cohort received an escalating dose of ipi: 0.3, 1, 3 or 5 mg/kg. Results: Median follow-up is 15.0 months. All pts had GVAX IT injection site reactions. Five of six pts at the higher ipi doses (3 and 5 mg/kg) developed Grade 2 or 3 immune-related endocrinopathy, consistent with hypophysitis manifested by adrenal insufficiency and/or hypothyroidism, all successfully treated with standard hormone replacement. Two pts were tapered off Synthroid within 6 months (m). There was no induction of the alpha-21-hydroxylase auto-antibody that is seen in 90% of cases of auto-immune adrenal insufficiency. One pt in the 5 mg group developed a Grade 3 dose-limiting alveolitis. PSA responses (declines > 50%) were seen in 5/6 treated at the two higher ipi doses with median response duration of 4.9 m (2 on-going at 7.2 m and 12.8 m). These PSA responses were associated with immune-related endocrinopathy but were not consistently correlated with declines in adrenal androgens. One pt had resolution of measurable disease on abdominal CT scan. Immunomonitoring studies showed T cell and dendritic cell activation, more pronounced at higher doses. Biopsies of injection sites showed T cell infiltration. Multiple tumor-reactive antibodies (abs) induced by tx were identified by serologic analysis (SEREX), including abs to filamin B. Screening against 20 defined prostate cancer antigens demonstrated induction of abs to PSMA and NY-ESO-1. Conclusions: The GVAX IT and ipilimumab combination is active in mHRPC. There was an association between PSA response and immune-related adverse events. The PSA responses cannot be accounted for by adrenal insufficiency. The relationship between clinical activity and serologic response to identified antigens is under investigation. Tx of 16 additional pts is planned.

No significant financial relationships to disclose.

Adjuvant treatment of colorectal cancer: towards tumor-specific immunotherapies

Colorectal cancer is one of the leading causes of cancer-related mortality. After a series of clinical trials, the adjuvant 5-FU based chemotherapy has established a definitive role in the management of stage III colon cancer. The precise role for chemotherapy in stage II disease remains under investigation and less toxic treatment modalities like active specific immunotherapy have emerged as potentially attractive alternatives. It is most likely that the adjuvant treatment of colon cancer will move towards more tumor-specific immunotherapies using antibody- or vaccination-based strategies. Phase II/III clinical trials investigating these different modalities in colorectal cancer are reviewed.

Circulating V(alpha24+) Vbeta11+ NKT cell numbers are decreased in a wide variety of diseases that are characterized by autoreactive tissue damage

Natural killer T (NKT) cells have been implicated as playing an important role in regulating immune responses. Defects in the NKT cell population were reported in animal autoimmune disease models and in distinct human autoimmune diseases. Here, we report that circulating V(alpha24+) Vbeta11+ NKT cell numbers are decreased in a broad variety of disorders with (auto)immune-mediated pathology, affecting the skin, bowel, central nervous system, and joints, regardless of disease duration or activity. Remarkably, normal circulating V(alpha24+) Vbeta11+ NKT cell numbers were found in Graves disease and coeliac disease. Since earlier studies noted a rise in NKT cells in myasthenia gravis, the picture emerges in which a defective NKT cell population is associated with autoreactive tissue damage rather than with the propensity to develop autoimmune disease. The present data support the idea that therapies aiming at the in vivo expansion of regulatory NKT cells might help to control immune-mediated damage in autoimmune disease.

Skin tests predict survival after autologous tumor cell vaccination in metastatic melanoma: experience in 81 patients

BACKGROUND

Currently there is no standard adjuvant treatment following surgical resection of metastatic melanoma. We investigated whether surgery followed by autologous tumor cell-BCG vaccination was beneficial for malignant melanoma patients. In this study we focus on the prognostic value of DTH response following vaccination therapy.

PATIENTS AND METHODS

Eighty-one patients with AJCC stage III and IV melanoma were selected. Whenever feasible, radical metastasectomy was performed. ASI was initiated by the administration of three weekly intra-cutaneous vaccinations with 10(7) irradiated autologous tumor cells, starting four weeks after surgery. Depending on the size of DTH response to the first three injections, subsequent vaccinations were planned. The first two vaccines also contained 10(7) BCG organisms as an immune stimulatory adjuvant.

RESULTS

Induration as well as erythema correlated strongly with survival (P < 0.0001 and P = 0.0004). After radical metastasectomy in stage III melanoma patients a five-year survival of 48% was observed. In stage IV disease, a five-year survival of 34% was seen, after radical surgery had been performed. When macroscopic disease was present at start of vaccination treatment, no clinical responses occurred. Apart from transient skin ulceration at the site of BCG-containing vaccinations, no serious side effects were observed.

CONCLUSIONS

This study shows that large-scale preparation of autologous melanoma cell vaccines is feasible. while vaccination results in DTH responses that correlate significantly with survival. ASI seemed to be beneficial in stage III and stage IV melanoma when given in the adjuvant setting, while causing only very mild side effects.

Human natural killer T cells acquire a memory-activated phenotype before birth

Natural killer T (NKT) cells have recently been shown to play an important role in the rejection of malignant tumors and in the regulation of autoimmune diseases. Potent antitumor effects of the marine sponge-derived NKT cell ligand KRN7000 were observed in mice. Therefore, the elucidation of the natural ligand of NKT cells, which is currently still unknown, might have important clinical consequences for the treatment of cancer and autoimmune diseases. Analysis of cord blood mononuclear cells from healthy term infants demonstrated that in sharp contrast with the vast majority of cord blood lymphocytes, human NKT cells have already acquired a memory-activated phenotype before birth. This observation indicates that NKT cells encounter a natural ligand during fetal life and that this ligand is unlikely to be of microbial origin.

In vivo T-B cell interactions and cytokine-production in the spleen

T-B cell interactions have a central role in the development of humoral immunity. The binding of a 39 kDa protein (gp39), selectively expressed on activated Th cells, to its receptor CD40, on B cells, results in the initial B cell activation. Thereafter, Th cell derived cytokines regulate the differentiation of B cells into antibody-forming cells. Most of these data are derived from in vitro experiments. This article discusses in vivo experiments dealing with T-B interactions. First, the immunohistochemical analysis of T cell activation (gp39 expression), cytokine and antibody production in murine spleens after injection of model antigens (TNP-Ficoll, TNP-KLH, and rabbit anti-IgD antibodies). Second, the in vivo role of gp39 and cytokines in these immune responses. Finally, by combining these in vivo experiments with in vitro data we present an in vivo model for T cell dependent antibody responses.

Tumour necrosis factor-alpha production during cytomegalovirus infection in immunosuppressed rats

The production of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1 and IL-6, all proinflammatory cytokines, was investigated in radiation-immunosuppressed rats infected with rat cytomegalovirus (RCMV). At day 7 post-infection, when the animals showed disease signs, high TNF-alpha levels were detected in the serum and in homogenates of various organ tissues. In contrast, IL-1 and IL-6 levels were not significantly elevated. Moreover, replication of RCMV induced TNF-alpha expression in different types of cells grown in vitro. When frozen tissue sections were examined by immunohistology, TNF-alpha-producing cells were found in areas with extensive pathology in the lungs, spleen and liver. Both lymphocytes and RCMV-infected cells were identified as the sources of TNF-alpha. Its abundance in RCMV-infected rats suggests an important role for TNF-alpha in CMV pathogenesis.

Suppression of rat cytomegalovirus replication by antibodies against gamma interferon

The role of gamma interferon (IFN-gamma) in the resolution of rat cytomegalovirus (RCMV) infection was investigated. In the spleen, IFN-gamma-producing cells reached maximum numbers on day 7 after infection. Prophylactic treatment with high doses of recombinant rat IFN-gamma exerted antiviral activity in fibroblasts and protected immunosuppressed rats against a lethal RCMV challenge. Remarkably, in immunocompetent rats, neutralization of endogenous IFN-gamma activity significantly reduced the numbers of RCMV antigen-expressing cells in the spleen, the predominant site of viral replication. Moreover, protection of radiation-immunosuppressed infected rats by transferred immune T cells was enhanced by coinjection of IFN-gamma neutralizing antibodies. The observations were paralleled by in vitro findings: low concentrations of IFN-gamma enhanced viral replication in both macrophages and fibroblasts. These data suggest that IFN-gamma can play different and even opposite roles in the regulation of RCMV replication in vivo; T lymphocytes may contribute to the progression of RCMV infection by secreting IFN-gamma.

Cloning of mouse Ox40: a T cell activation marker that may mediate T-B cell interactions

A cDNA library was prepared from the murine Th cell line Th2 D.10 and used to clone the murine homologue of Ox40 by polymerase chain reaction. Comparison of the mouse sequence with the rat revealed greater than 90% homology between the two sequences at both the DNA and protein level. Northern blot analysis found that, as in the rat, Ox40 expression appears to be restricted to activated T cells. A chimeric receptor globulin was prepared to include the mouse Ox40 extracellular domain coupled to the hinge-CH2-CH3 domains of human IgG1 (Ox40-Ig). This soluble form of the molecular was then used to identify cells bearing a ligand for Ox40. FACS analysis revealed that Ox40-Ig bound to a subset of peritoneal B cells as well as to a fraction of LPS-activated splenic B cells. Immunostaining of spleen sections using an Ag-specific conjugate and Ox40-Ig found a significant proportion of antibody-forming cells co-stained with Ox40-Ig. Immunoprecipitation of cell-surface radiolabeled peritoneal B cells suggests a specific interaction with a protein of 70 kDa.

Cloning of mouse Ox40: a T cell activation marker that may mediate T-B cell interactions

A cDNA library was prepared from the murine Th cell line Th2 D.10 and used to clone the murine homologue of Ox40 by polymerase chain reaction. Comparison of the mouse sequence with the rat revealed greater than 90% homology between the two sequences at both the DNA and protein level. Northern blot analysis found that, as in the rat, Ox40 expression appears to be restricted to activated T cells. A chimeric receptor globulin was prepared to include the mouse Ox40 extracellular domain coupled to the hinge-CH2-CH3 domains of human IgG1 (Ox40-Ig). This soluble form of the molecular was then used to identify cells bearing a ligand for Ox40. FACS analysis revealed that Ox40-Ig bound to a subset of peritoneal B cells as well as to a fraction of LPS-activated splenic B cells. Immunostaining of spleen sections using an Ag-specific conjugate and Ox40-Ig found a significant proportion of antibody-forming cells co-stained with Ox40-Ig. Immunoprecipitation of cell-surface radiolabeled peritoneal B cells suggests a specific interaction with a protein of 70 kDa.

Immunohistochemical detection of co-localizing cytokine and antibody producing cells in the extrafollicular area of human palatine tonsils

In vitro experiments have documented the role of cytokines in the regulation of the human humoral immune response. Which cytokines are operative in vivo and in which lymphoid compartment interactions between cytokine-producing T cells and antibody-forming B cells occur is still unclear. For that reason we studied human tonsils using immunohistochemical techniques. In tissue sections from tonsils in a resting stage after recurrent tonsillitis we observed cells producing IL-1 alpha and tumour necrosis factor-alpha (TNF-alpha) which were exclusively localized in the mantle zone of the follicle and in the extrafollicular area. Furthermore, a high frequency of interferon-gamma (IFN-gamma)-producing cells was detected in the extrafollicular area, but not inside the follicles. Occasional IL-2- and IL-4-producing cells were found in the extrafollicular area. Immunohistochemical detection of antibody isotypes revealed that B cells, IgM-membrane-positive, were localized inside the follicles and mantle zones, whereas IgD-membrane-positive cells were mainly found in the mantle zones of secondary follicles. In contrast, plasma cells producing IgG1-4 and IgA1-2 were found in the extrafollicular area. No IgD and IgE antibody-forming cells were detected in tonsils, whereas IgM antibody-forming cells were detected in the extrafollicular area. The co-localization of cytokine-producing cells and antibody-forming cells in human tonsil suggests that T-B cell interactions, required for B cell differentiation and isotype switching, take place in the extrafollicular area.

Stored platelets release nucleotides as inhibitors of platelet function

It is well known that the function of platelets decreases progressively during storage of platelet concentrates at room temperature. To investigate this phenomenon in more detail, we have resuspended platelets that had been stored for 24 h or 72 h in fresh plasma, and we have measured the aggregation response and the ATP secretion. Conversely, the effect of plasma in which platelet concentrates (PC) had been stored for 24 h or 72 h, was tested on fresh platelets. Both the aggregation response to collagen and ADP and the collagen-induced ATP secretion of stored platelets partially recovered after incubation with fresh plasma (p < 0.05). The same parameters measured with fresh platelets incubated in stored PC-plasma were found to be significantly reduced in comparison with the response of fresh platelets in fresh plasma (p < 0.05). Finally, platelets were stored in a plasma-free medium, suitable for platelet storage and the supernatant was tested. This supernatant inhibited the function of fresh platelets in a storage time-dependent fashion. Boiling of these supernatants did not change the inhibiting capacities, whereas filtration over active charcoal did. Analysis of this supernatant revealed AMP and diadenosine tetraphosphate, which both inhibit platelet function. These data show that stored platelets release nucleotides that inhibit platelet function in a reversible manner. This phenomenon may contribute to the decrease of platelet function during storage and the recovery of platelet function after transfusion.

Complement-mediated follicular localization of T-independent type-2 antigens: the role of marginal zone macrophages revisited

In this study we demonstrate a hitherto undescribed phenomenon, namely that thymus-independent type-2 antigens (TI-2 Ag) localize in splenic follicles within 1 h after administration. The follicular localization of 2,4,6-trinitrophenyl (TNP)-Ficoll was not antibody mediated. In addition in case of high-dose administration we observed a relatively large amount of TI-2 Ag in marginal zone macrophages. However, after low-dose administration we observed a preferential localization of TNP-Ficoll in the splenic follicles. Detection of TNP-haptenated Ag in cryostat sections of murine spleens was performed with a high-affinity TNP-specific monoclonal antibody conjugated to beta-galactosidase. Within minutes after injection the TI-2 Ag localized in the marginal zone, attached to marginal zone macrophages and B cells. Twenty minutes after injection the Ag was also detected in the follicles and gradually accumulated there until 7 h after injection. Thereafter, the amount of follicular Ag gradually decreased but was still detectable up to 14 days after immunization. The follicular localization of TNP-Ficoll was complement dependent in contrast to the binding to and uptake by marginal zone macrophages. Double staining revealed that Ag was bound by macrophages, B cells and follicular dendritic cells. Haptenated thymus-dependent (TD) Ag localized exclusively in the red pulp macrophages. In vivo macrophage elimination drastically increased the amount of TNP-Ficoll in the follicles, and enhanced the humoral immune response at low doses of Ag. Moreover, complement deprivation of mice abrogated the localization of TI-2 Ag in the follicles, and led to a decreased humoral TI-2 immune response. In conclusion, we demonstrate for the first time that TI-2 Ag localize in follicles. Moreover, the presented results provide further evidence that B cells and follicular localized Ag play an important role in the induction of humoral TI-2 immune responses.

Synthetic peptide conjugates with horseradish peroxidase and beta-galactosidase for use in epitope-specific immunocytochemistry and ELISA

Synthetic peptide-alkaline phosphatase conjugates can be used to detect the epitope specificity of (i) antibody-forming cells in vivo by immunocytochemistry; (ii) of antibody secreting cells in vitro by spot-ELISA; and (iii) antibodies in solution by capture ELISA. The availability of synthetic peptide-enzyme conjugates using detector enzymes other than alkaline phosphatase would offer several important advantages, for example in double staining approaches. This paper reports the production of synthetic peptide-horseradish peroxidase conjugates and synthetic peptide-beta-galactosidase conjugates. A peptide of 21 amino acids (SP 29) was coupled to peroxidase in seven differing molar ratios of peptide over peroxidase, ranging from 1:3.4 to 1:575, using periodate oxidation of the enzyme. SP 29 was coupled to beta-galactosidase in four molar ratios ranging from 1.25 to 10, using glutaraldehyde pre-activation of the enzyme. The enzyme activity of the different conjugates was determined, the conjugates were tested in direct capture-ELISA with peptide-specific monoclonal antibodies, and the conjugates were tested in immunocytochemistry to detect peptide-specific B cells. The results show that the conjugates perform best if the peptide is coupled to the enzyme at relatively low molar ratios (1-30). The availability of these new peptide-enzyme conjugates broadens the applicability of synthetic peptides for detection purposes in several assay systems.

In vivo kinetics and characterization of IFN-gamma-producing cells during a thymus-independent immune response

Using immunohistochemical techniques, we studied IFN-gamma-producing cells (IFN-gamma-PC) in vivo during immune responses to thymus-independent type-2 (TI-2) Ag. Detection of IFN-gamma-PC in cryostat sections of spleen-tissue was performed with an enzyme labeled mAb directed against IFN-gamma. After TNP-Ficoll immunization, IFN-gamma-PC and TNP-specific antibody-forming cells (TNP-AFC) displayed similar kinetics reaching a maximum number at day 5 to 7. The IFN-gamma-PC were localized in the same compartment as TNP-AFC and a part of them in juxtaposition to TNP-AFC. Immunization with other TI-2 Ag resulted also in a significant increase of the number of IFN-gamma-PC. In a parallel experiment we found both in vivo and in an ELISA-spot assay a significant increase of the number of IFN-gamma-PC and IFN-gamma-spot-forming-cells, respectively, in spleens of mice 6 to 7 days after TNP-Ficoll immunization. Double staining of spleen sections for IFN-gamma and surface Ag revealed that 5 to 7 days after TNP-Ficoll immunization, +/- 40% of the IFN-gamma-PC expressed the MT4 Ag (CD4), +/- 50% the Lyt-2+ Ag (CD8) and +/- 10% the asialo-GM1 Ag (NK cell). This study represents the first description of the in vivo activity and characterization of IFN-gamma-PC during a TI-2 immune response. Moreover, the presented data confirm suggestions from in vitro investigations that IFN-gamma and T cells may play a direct role in the in vivo regulation of a primary immune response against a TI-2 Ag.

In vivo kinetics and characterization of IFN-gamma-producing cells during a thymus-independent immune response

Using immunohistochemical techniques, we studied IFN-gamma-producing cells (IFN-gamma-PC) in vivo during immune responses to thymus-independent type-2 (TI-2) Ag. Detection of IFN-gamma-PC in cryostat sections of spleen-tissue was performed with an enzyme labeled mAb directed against IFN-gamma. After TNP-Ficoll immunization, IFN-gamma-PC and TNP-specific antibody-forming cells (TNP-AFC) displayed similar kinetics reaching a maximum number at day 5 to 7. The IFN-gamma-PC were localized in the same compartment as TNP-AFC and a part of them in juxtaposition to TNP-AFC. Immunization with other TI-2 Ag resulted also in a significant increase of the number of IFN-gamma-PC. In a parallel experiment we found both in vivo and in an ELISA-spot assay a significant increase of the number of IFN-gamma-PC and IFN-gamma-spot-forming-cells, respectively, in spleens of mice 6 to 7 days after TNP-Ficoll immunization. Double staining of spleen sections for IFN-gamma and surface Ag revealed that 5 to 7 days after TNP-Ficoll immunization, +/- 40% of the IFN-gamma-PC expressed the MT4 Ag (CD4), +/- 50% the Lyt-2+ Ag (CD8) and +/- 10% the asialo-GM1 Ag (NK cell). This study represents the first description of the in vivo activity and characterization of IFN-gamma-PC during a TI-2 immune response. Moreover, the presented data confirm suggestions from in vitro investigations that IFN-gamma and T cells may play a direct role in the in vivo regulation of a primary immune response against a TI-2 Ag.

In vitro evaluation of buffy-coat-derived platelet concentrates stored in a synthetic medium

Human blood platelets, prepared by the buffy-coat method, were prepared and stored in different synthetic media. In a synthetic medium based on gluconate, acetate and citrate (GAC), the pH was 6.8 on day 6. This medium was chosen for further evaluation. The total platelet count and the leukocyte contamination were significantly lower in the platelet concentrates (PCs) prepared in GAC compared to PCs prepared in plasma. Platelets stored in plasma or in GAC were equally functional when tested for aggregation and adenosine triphosphate (ATP) secretion. Only stimuli that act through the arachidonic-acid pathway induced a lower platelet response in GAC. Platelet morphology was quantified by measuring the difference in light transmission during stirring at different rates in an aggregometer; no significant differences for platelets stored in GAC as compared to plasma were observed. Activation of platelets was measured by binding of monoclonal antibodies (McAb) against the Gp IIb/IIIa complex and against activation-dependent antigens (GMP 140 from the alpha-granules and a 53-kD glycoprotein from the lysosomal granules). There was no difference in binding of these McAb between platelets prepared and stored in plasma or GAC. We conclude that platelets prepared by the buffy-coat method and stored in GAC have the same in vitro qualities as platelets stored in plasma, except for the lower aggregation response by the arachidonic-acid pathway. This is probably due to an acetate-induced decrease in intracellular pH.