Immune responses to tetanus vaccination in Italian healthy subjects and children with recurrent infections.

The ability of vaccine antigen to generate protection is a challenge that cannot be restricted to the antibody response; however, the contribution of T cell-mediated mechanisms has not been extensively analyzed. Age and administration to specific categories of patients, i.e. children with recurrent infections (RI), are some of the factors that might affect the vaccine immune response. We investigated the humoral and cellular response to tetanus toxoid (TT) vaccine in 104 healthy children (HC), 11 newborns and 22 healthy adults to characterize the status of immunity according to age and compared it to 118 RI children. Humoral and cellular responses varied in both groups according to age and doses of TT administered. The prevalence of antibody and cellular response was similar in both cohorts (HC 88 percent and 82 percent versus RI 86 percent and 85 percent), however, TT antibody values were significantly higher in 12-18 months old RI children compared to HC (median: 5 IU/ml vs 1.10 IU/ml) (p = 0.02). The lack of an efficient immune response was observed in 12-15 percent of children from both cohorts. Our data showed that specific antibodies were responsible for early protection, whereas cell-mediated mechanisms may contribute to the generation of long-term immunity after an appropriate vaccine recall. The occurrence of higher TT antibody values in 12-18 months old RI children deserves additional research to determine whether they are caused by different infectious agents and/or by other environmental factors. Clarification of this issue is important for categorizing patients into an optimal vaccine policy.

Novel p62dok family members, dok-4 and dok-5, are substrates of the c-Ret receptor tyrosine kinase and mediate neuronal differentiation.

Docking proteins are substrates of tyrosine kinases and function in the recruitment and assembly of specific signal transduction molecules. Here we found that p62dok family members act as substrates for the c-Ret receptor tyrosine kinase. In addition to dok-1, dok-2, and dok-3, we identified two new family members, dok-4 and dok-5, that can directly associate with Y1062 of c-Ret. Dok-4 and dok-5 constitute a subgroup of dok family members that is coexpressed with c-Ret in various neuronal tissues. Activated c-Ret promotes neurite outgrowth of PC12 cells; for this activity, Y1062 in c-Ret is essential. c-Ret/dok fusion proteins, in which Y1062 of c-Ret is deleted and replaced by the sequences of dok-4 or dok-5, induce ligand-dependent axonal outgrowth of PC12 cells, whereas a c-Ret fusion containing dok-2 sequences does not elicit this response. Dok-4 and dok-5 do not associate with rasGAP or Nck, in contrast to p62dok and dok-2. Moreover, dok-4 and dok-5 enhance c-Ret-dependent activation of mitogen-activated protein kinase. Thus, we have identified a subclass of p62dok proteins that are putative links with downstream effectors of c-Ret in neuronal differentiation.

Surgical site infections in HIV-infected patients: results from an Italian prospective multicenter observational study.

BACKGROUND: The quality of life of the HIV-infected population in developed countries has substantially improved over the years. Accordingly, the clinical limitations in the surgical treatment of the HIV-infected patients are becoming fewer, and the number of HIV-infected patients undergoing surgical interventions of all types is increasing. However, available data on the incidence and risk factors for post-surgical complications, such as surgical site infections (SSI), in HIV-infected patients are still limited and often controversial. The aim of this study was to determine the incidence and the associated risk factors for SSI in HIV-infected patients. METHODS: A 1-year observational prospective multicenter surveillance study was conducted in 11 Italian Infectious Diseases Clinical Centers from which 305 consecutive HIV-infected patients undergoing different surgical procedures were enrolled. Postdischarge surveillance was conducted within 30 days after surgery. A number of variables were included in a multivariate analysis aimed at assessing potential risk factors for SSI, including body mass index, diabetes, Hepatitis C (HCV) and hepatitis B virus infection, lipodistrophy, HIV viral load, CD4 cell count and white blood cell count, preoperative hospital stay, National Nosocomial Infection Surveillance (NNIS) risk score, and any antimicrobial prophylaxis. RESULTS: SSI occurred in 29 of 305 (9.5%) patients, of which 17 (58.6%) SSI occurred during hospital stay, and 12 (41.4%) occurred during the postdischarge period. The SSI of the 29 patients were classified as superficial (21, 72.4%), deep (four, 13.8%), organ/space (one, 3.4%), and sepsis (three, 10.3%). Nearly 50% of the superficial and 50% of the deep SSI occurred during the postdischarge period. Organ/space infection and sepsis accounted for 13.7% of all SSI and were observed during the in-hospital stay. The multivariate analysis revealed that HCV co-infection was significantly associated to SSI occurrence. Total hospital stay was longer among patients with SSI than among those without SSI (p = 0.041). CONCLUSION: Although 92.5% of our HIV-infected patients presented a NNIS score < or = 1, the SSI rate was twofold higher than that reported in Italian and European studies for the general population, with more severe clinical presentations. This is the first report of an association between HCV-HIV co-infection and SSI occurrence. Additionally, the viro-immunological status of our patients was not related to SSI occurrence, which suggests the need for further research for other potential risk factors that may be implicated in the occurrence of SSI.

A prospective study on children with initial diagnosis of transient hypogammaglobulinemia of infancy: results from the Italian Primary Immunodeficiency Network.

Transient hypogammaglobulinemia of infancy (THI) is a heterogeneous disorder characterized by reduced serum IgG levels in early infancy. A putative diagnosis is initially made after exclusion of other causes of hypogammaglobulinemia while a definitive diagnosis of THI can only be made a posteriori in patients with normalization of IgG levels. The aim of this study is to characterize clinical and immunological features of children with an initial diagnosis of THI in correlation to natural outcome, and to assess predictive laboratory parameters of clinical evolution for this disorder. We prospectively analysed clinical and immunological characteristics of 77 THI children at initial diagnosis and of 57 patients at follow-up. Memory B cell subsets and in vitro immunoglobulin production were evaluated. Seventy patients (91 percent) showed clinical symptoms. Patients suffered from infections (91 percent), allergies (47 percent) and autoimmune disease (4 percent). During follow-up 41/57 children (72 percent) normalized IgG values, mostly within 24 months of age (p less than 0.001), allowing the diagnosis of THI. The 16 children who did not normalize their IgG levels showed a higher frequency of severe infections and autoimmune disease (p less than 0.01). Moreover, they expressed a reduced frequency of IgM and switched memory B cells (p less than 0.01) and an inability to produce IgG in vitro (p less than 0.02). We conclude that most patients with an initial diagnosis of THI spontaneously recover within 24 months of age and have a benign clinical course, while a subgroup of children with undefined hypogammaglobulinemia share a clinical and immunological profile with other primary immunodeficiencies. Early recognition of children with hypogammaglobulinemia during infancy who are likely to suffer from permanent immunodeficiencies later in life would allow prompt and appropriate laboratory and clinical interventions.

Kinetics of the T-cell receptor CD4 and CD8 V beta repertoire in HIV-1 vertically infected infants early treated with HAART.

OBJECTIVES: To determine the kinetics and the relationship between the T-cell receptor V beta (TCRBV) complementary determining region 3 length, the CD4 T-cell count and HIV viral load changes in HIV-1 infected infants treated early with highly active antiretroviral therapy (HAART) during 1 year of follow-up. DESIGN: Two HIV-1 vertically infected infants, two HIV-1 vertically exposed uninfected and two healthy controls were analysed by spectratyping. Evaluation of viral load, CD4 naive and memory cell counts and a proliferation test were also carried out. METHODS: Twenty-six families and subfamilies of the TCR on CD4 and CD8 T cells were analyzed by spectratyping. Flow cytometric analysis on peripheral blood mononuclear cells for CD4CD45Ra, CD4CD45Ro, CD8CD38, proliferation tests and plasma viral load measurements were performed at baseline, 1, 6 and after 12 months of therapy. RESULTS: HAART induced a marked reduction of viral load in both HIV-1 infected infants and an increase to normal CD4 T-cell count in the symptomatic infant. At baseline the TCRBV family distribution in the majority of CD8 and a few of the CD4 T cells was highly perturbed, with several TCRBV families showing a monoclonal/oligoclonal distribution. During HAART a normalization of the TCR repertoire in both CD8 and CD4 subsets occurred. TCR repertoire normalization was associated with a good virological and immunological response. CONCLUSION: These results suggest that complete and early virus replication control as a result of early HAART leads to a marked reduction of T-cell oligoclonality and is an essential prerequisite to the development of a polyclonal immune response in HIV-1 infected infants.

Production and characterization of monoclonal antibodies against DNA single ring diamines adducts.

The synthetic conjugate of the genotoxic compound 2,4 diaminotoluene (2,4 DAT) with gelatin (2,4 DAT-GEL) was employed to elicit specific antibodies directed against a restricted class of aromatic diamines. Using this immunogen, mouse monoclonal antibodies (MAbs) have been produced. These MAbs have been characterized and used in ELISA to detect 2,4 DAT covalently linked to biopolymers. The MAbs could bind to different synthetic 2,4 DAT-biopolymer adducts as well as to DNA from rats treated in vivo with the aromatic diamine, but they did not react with gelatin or biopolymers alone. The use of these MAbs has been investigated in order to develop a highly sensitive test to detect adducts of this genotoxic compound with nuclear DNA.

[Cervical maturation and induction of labor with PgE2 gel. Authors' experience]. / Maturazione del collo uterino e induzione del travaglio di parto con PgE2 gel. Nostra esperienza.

BACKGROUND: To evaluate the efficacy and safety of intracervical prostaglandin E2 gel applications (PgE2) for cervical ripening and induction of labor in relation to parity and admission cervical score. MATERIALS AND METHODS: One hundred and thirty-nine hospitalized patients with an unfavorable cervix (Bishop score < or = 4) received a dose of commercially available endocervical dinoprostone gel 0.5 mg. On the basis of cervical scores, the gel was reapplied at a 12-hour interval for a maximum of two doses. If cervical ripening was successful (Bishop score > 4) but labor did not start within 12 hours from the last dose of gel, labor was induced with oxytocin infusion or with 1 or 2 doses of intravaginal dinoprostone. RESULTS: Intracervical gel was effective for preparing an unfavorable cervix in 87.1% of patients. In 53.1% of nulliparous with admission Bishop < or = 2 the interval between the first application of gel and delivery was higher than 24 hours whereas in all patients with parity > or = 1 and initial Bishop score between 3 and 4 delivery was achieved within 24 hours. The cesarean delivery rates in the two groups were 23.9% and 43% respectively. CONCLUSIONS: The interval from the first application of gel to delivery is strongly influenced by parity and initial cervical score. Vaginal delivery can be expected in four fifths of patients with an unfavorable cervix who undergo pre-induction cervical ripening with prostaglandin E2 gel.

Insight into B cell development and differentiation.

The main topic of this article is B cell development and differentiation, with a special focus on the mechanisms and molecules that regulate the expression of humoral immunity. Molecular epidemiological analysis was performed on the genes responsible for the X-linked agammaglobulinemia (XLA) phenotype of the majority of Italian patients and their distinct mutations were characterized. Mutations in Bruton's tyrosine kinase (BTK), a member of Tec Family of protein tyrosine kinases, have been found to be mainly responsible for XLA disease. The exact function of BTK in signal transduction is not yet known; thus, the specific role of BTK in receptor-dependent calcium signaling and the pro-antiapoptotic regulatory activity was addressed by transfecting RAMOS-1, a BTK-deficient human Burkitt's/B cell leukemia line with wild-type and mutant constructs. This work may provide clues about critical sites in the molecule and give support for gene therapy as a potential successful approach to XLA. Another aspect of this research is the identification and dissection of the molecular events that are likely to be directly related to the ability to express various isotypes of immunoglobulin with differing function and certain B cell immunodeficiency, mainly common variable disease and non-X-linked hyperIgM. B cell development and maturation steps in different compartments of the immune system are tracked by the analysis of cell-surface molecules and components of the signal transduction pathways, i.e. CD40, CD30, CD27, CD38, CD22 and CD24. A few components involved in B cell development, maturation and differentiation and their specific functional role are at least partially known, but these are far from fitting into an understandable pathway at present.

The effect of imatinib mesylate on the proliferation, invasive ability, and radiosensitivity of retinoblastoma cell lines.

PURPOSE: Our aim was to evaluate the potential effect of imatinib mesylate (IM), a small molecule that specifically inhibits the tyrosine quinase receptors, on the proliferation and invasive abilities of two human retinoblastoma (Rb) cell lines. Furthermore, the ability of IM to radiosensitize Rb cells was evaluated. The potential targets of IM (C-kit, PDGRF-α and -ß, and c-Abl) were also investigated in these cell lines. METHODS: Two human Rb cell lines (WERI-RB-1 and Y79) were cultured under normal growth conditions. An MTT-based proliferation assay and a Matrigel invasion assay were performed with and without exposure to 10 µM of IM. The cells were also irradiated with graded dosages of 0, 2, 4, 6, 8, and 10 Gy with and without IM and their proliferations rates were analyzed. Western blot and immunocytochemical analysis of cytospins were performed to evaluate the expression of C-kit, PDGRF-α and -ß, and c-Abl. RESULTS: When IM was added to both cell lines a statistically significant (P<0.05) reduction in proliferation and invasive ability were observed. Exposure to IM also significantly increased the radiosensitivity of both Rb cell lines. The c-Abl expression was strongly positive, PDGRF-α and -ß expression were also positive but the C-kit expression was negative in both cell lines. CONCLUSIONS: These results indicate that Gleevec may be useful as an adjuvant treatment in Rb patients, specially those considered for radiation therapy.

Needs of caregivers of the patients with dementia.

This study was conducted to isolate the needs families express both for medical and psychological care, and for educational and social support in 112 caregivers of patients affected by moderate to severe dementia (mini mental state examination=MMSE score: 9+/-7) consecutively recruited at our Memory Clinic, to develop approaches as individualized as possible. The medical needs caregivers express are mainly relative to a better knowledge of the disease (78%) and the exact diagnosis (65%); the education-related needs are mainly relative to the acquisition of communicational skills (83%) and the optimal handling of cognitive (77%) and behavioral disorders (81%); the psychological ones mainly concern the area of assistance induced emotional stress management (37%) and the elaboration of feelings such as anxiety, rage and guilt (49%). Variance analysis shows a correlation between emotional caregivers' needs and the subjective and objective burdens they carry. Despite the attention to the role families play in caring for patients with a diagnoses of moderate to severe dementia, caregivers still express low levels of illness-consciousness and high levels of psychological discomfort. A lot more ought to be done in order to provide better information about the disease, about appropriate cognitive and behavioral disorder management skills, and about viable psychological support.

Amfenac increases the radiosensitivity of uveal melanoma cell lines.

PURPOSE: To evaluate the proliferation rates of five human uveal melanoma (UM) cell lines after treatment with amfenac, a cyclooxygenase (COX)-2 inhibitor, and subsequent radiation exposure. METHODS: Five human UM cell lines (92.1, SP6.5, MKT-BR, OCM-1, and UW-1) and one human fibroblast cell line (BJ) were incubated with amfenac. Treated and non-treated cell lines were then exposed to various doses of gammaradiation: 0, 2, 4, 6, and 8 Gy. Sulphorhodamine-B assay was used to assess proliferation rates 48 h post-radiation. RESULTS: Treatment of UM cell lines with amfenac prior to radiation led to a marked reduction in proliferation rates. This difference was statistically significant in all cell lines at every radiation dose (P<0.005), with the exception of 92.1 at 2 Gy (P=0.157). Fibroblasts treated with amfenac showed significantly higher proliferation rates after 2 and 8 Gy, with no significant differences at 0, 4, and 6 Gy. CONCLUSIONS: The radiosensitivity of UM cell lines was increased by the administration of amfenac, the active metabolite of nepafenac. There appears to be a radioprotective effect of amfenac on human fibroblasts. The topical administration of nepafenac may decrease tumour recurrence and radiation-induced complications while broadening the indications for radiotherapy by treating larger tumours.

Expression of the metastasis suppressor gene KISS1 in uveal melanoma.

PURPOSE: Uveal melanoma (UM) is the most common primary malignant intraocular tumour in adults. Forty-five percent of UM patients develop metastasis within 15 years of initial diagnosis. KISS1, a human metastasis suppressor gene, has been reported to play a role in various human malignancies. The purpose of this study was to investigate the expression of KISS1 in UM and its potential value as a prognostic marker. METHODS: Thirty-seven cases of paraffin-embedded human UM specimens were immunostained with a KISS1 antibody. Clinical-pathological data were obtained. The relationship between the clinical-pathological data and the expression of KISS1 was evaluated. Moreover, the survival rates of the patients were also assessed. Five UM cell lines (92.1, OCM-1, MKTBR, UW1 and SP6.5) were assayed for KISS1 expression. In addition, real-time PCR was used to determine mRNA levels of KISS1and its receptor GPR54in these cell lines. RESULTS: The immunohistochemical results of KISS1 expression displayed cytoplasmic staining in 84% of UM specimens. Low KISS1 expression was associated with a higher risk of metastatic disease (P<0.05). Furthermore, we found that KISS1 was expressed in all five UM cells lines. Real-time PCR analysis confirmed the presence of both KISS1and its receptor GPR54in all five human UM cell lines. CONCLUSIONS: To the best of our knowledge, this is the first time that KISS1has been characterized in UM. The correlation between KISS1 expression and UM survival rate suggests an important role for KISS1as a prognostic marker in this particular tumour.

Humoral immune responses and CD27+ B cells in children with DiGeorge syndrome (22q11.2 deletion syndrome).

The spectrum of T-cell abnormalities in 22q11.2 syndrome is quite broad, ranging from profound and life threatening to non-existent defects. Humoral abnormalities have been described in some of these patients, although no data are currently available on their phenotypical and functional B cell subsets. The purpose of this study was to investigate humoral immune function in a cohort of 13 children with DiGeorge syndrome by immunophenotyping B and by analysing their functionality in vivo. Humoral immunity was assessed by serum immunoglobulin evaluation, IgG subclasses determination, and testing of specific antibody titers to recall antigens. B cells were analyzed by flow cytometry and the relevant percentage of membrane surface expression of CD27, IgM, IgD was evaluated. In our cohort, one of 13 children (7.7%) had a complete IgA deficiency, four of 13 (30.7%) had minor immunoglobulin abnormalities, and five (38%) had an impaired production of specific antibodies. Five of 13 children (38%) had recurrent infections. Interestingly, peripheral CD27+ B cells were reduced in our patients as compared with age-matched healthy controls, and this decrement was statistically significant for IgM+ IgD+ CD27+ B cells. Immunoglobulin abnormalities were associated with the occurrence of recurrent infections. We conclude that a significant proportion of patients with DiGeorge syndrome have defective humoral immunity, which may represent an additional pathogenic mechanism underlying the increased susceptibility to infections. Whether the decreased CD27+ B-cell subset might be one of the defects that contribute to impaired humoral immunity, and to susceptibility to infection remains to be elucidated.

Lentiviral transduction of human postnatal skeletal (stromal, mesenchymal) stem cells: in vivo transplantation and gene silencing.

Systems for gene transfer and silencing in human skeletal stem cells (hSSCs, also stromal or mesenchymal stem cells) are important for addressing critical issues in basic hSSC and skeletal biology and for developing gene therapy strategies for treatment of skeletal diseases. Whereas recent studies have shown the efficacy of lentiviral transduction for gene transfer in hSSCs in vitro, no study has yet proven that lentivector-transduced hSSCs retain their distinctive organogenic potential in vivo, as probed by in vivo transplantation assays. Therefore, in addition to analyzing the in vitro growth and differentiation properties of hSSCs transduced with advanced-generation lentivectors, we ectopically transplanted LV-eGFP-transduced hSSCs (along with an osteoconductive carrier) in the subcutaneous tissue of immunocompromised mice. eGFP-transduced cells formed heterotopic ossicles, generating osteoblasts, osteocytes, and stromal cells in vivo, which still expressed GFP at 2 months after transplantation. eGFP-expressing cells could be recovered from the ossicles 8 weeks posttransplantation and reestablished in culture as viable and proliferating cells. Further, we investigated the possibility of silencing individual genes in hSSCs using lentivectors encoding short hairpin precursors of RNA interfering sequences under the control of the Pol-III-dependent H1 promoter. Significant long-term silencing of both lamin A/C and GFP (an endogenous gene and a transgene, respectively) was obtained with lentivectors encoding shRNAs. These data provide the basis for analysis of the effect of gene knockdown during the organogenesis of bone in the in vivo transplantation system and for further studies on the silencing of alleles carrying dominant, disease-causing mutations.

Surface expressed heat-shock proteins by stressed or human immunodeficiency virus (HIV)-infected lymphoid cells represent the target for antibody-dependent cellular cytotoxicity.

The expression of heat-shock proteins (HSP) of the 72,000 MW family by Daudi and H9 lymphoma cells has been investigated by flow cytometry. It has been found that both heat-stressed and chronically human immunodeficiency virus (HIV)-infected lymphomas show an increased expression of heat-shock proteins (HSP). Moreover, murine monoclonal antibody (mAb) against 72,000 MW HSP was able to mediate antibody-dependent cellular cytotoxicity (ADCC) using peripheral blood lymphocytes (PBL) as effector cells. All target cells used in these experiments were efficiently lysed in the presence of anti-HSP antibody suggesting a role of membrane HSP in the elimination of stressed or infected cells.

Interaction between Gab1 and the c-Met receptor tyrosine kinase is responsible for epithelial morphogenesis.

The proteins Gab1 and the related DOS (for 'daughter of sevenless') each bind to substrates of tyrosine kinases like Grb2 or Corkscrew, and act in signalling pathways downstream of tyrosine kinase receptors. Here we show that Gab1 interacts directly with the c-met-encoded receptor tyrosine kinase but not with a number of other tyrosine kinases from different subfamilies. A newly identified proline-rich domain of Gab1 is responsible for the binding of this protein to the tyrosine-phosphorylated bidentate docking site in c-Met. Expression of Gab1 in epithelial cells is sufficient to induce the c-Met-specific activities, including branching morphogenesis. Thus we have discovered a new phosphotyrosine interaction domain in Gab1 and shown that Gab1 is the substrate of the c-Met receptor tyrosine kinase that mediates epithelial morphogenesis.

Recognition and killing of tumour cells expressing heat shock protein 65 kD with immunotoxins containing saporin.

The expression of heat shock proteins (HSP) of the 65 kD family (groEL) has been observed by flow cytometry using murine monoclonal antibody (MoAb) anti-HSP 65 kD (ML30) on the surface of B (Daudi) or T (H9) lymphoma cells, on a monocyte cell line (U937) and also on a primary culture of a human pancreatic carcinoma (HPC). Moreover, the MoAb ML30 was coupled to Saporin 6, a ribosome-inactivating protein recovered from the seeds of Saponaria officinalis, to kill HSP-expressing cells with a specific immunotoxin. An indirect method using first MoAb ML30 and then anti-mouse IgG1 immunotoxin was also performed. With this method a human serum positive for HSP65-antibodies was tested using anti-human IgG1 or IgM immunotoxins. All cell lines were inhibited when preincubated with the specific immunotoxin directed to HSP65 (ML30 SO6), although H9 cells were susceptible to immunotoxin only after thermal stress. Daudi and HPC cells were inhibited both after long-term culture and when freshly explanted from SCID mice. Proliferation of the U937 monocytic cell line, that constitutively expresses high levels of HSP65 on the surface (as determined by flow cytometry), was completely inhibited (100% inhibition) by the ML30 SO6. However, not all tumour cells constitutively express high levels of surface HSP65, as determined by cytometric analysis. For this reason it was not always possible to obtain complete inhibition of cellular proliferation.

Flow cytometric analysis of the early phases of apoptosis by cellular and nuclear techniques.

The early events occurring during apoptosis at the plasma membrane, chromatin, and mitochondrial levels were investigated in freshly isolated irradiated human lymphocytes, growth factor-deprived cultured human lymphocytes, and dexamethasone (DEX)-treated murine thymocytes. In intact, unfixed cells, evaluation of the light scatter properties and of DNA stainability with ethidium bromide (EB) allowed a cell subset suggestive for initial apoptosis to be identified. The apoptotic nature of these cells was confirmed by cell sorting in irradiated human lymphocyte model. EB could not be substituted for by propidium iodide, indicating that the nature of DNA probe used is of major importance for detecting initial apoptotic changes. Because mitochondria are thought to represent a primary target during apoptosis, we measured the uptake of mitochondria transmembrane potential sensitive (Rhodamine 123) and nonsensitive (10-nonyl-acridine-orange) probes concomitantly with EB uptake. Cells starting apoptosis had an enhanced incorporation of both mitochondria dyes, which in combination with EB identified several cell subsets. This suggests that complex alterations in mitochondrial structure and functioning occur in the early stages of apoptosis. To investigate phenomena occurring at the chromatin level in similar phases of apoptosis, irradiated human lymphocytes and DEX-treated murine thymocytes were disrupted and DNA stainability assessed in nuclear suspensions. A transient increase in DNA stainability, i.e., the appearance of distinct hyperdiploid peaks in the human model and a generalised upward shift of the G0/1 peak in the murine model, was observed in the early phases of apoptosis concomitantly with specific alterations in light scattering properties. These findings suggest that chromatin texture is altered in early apoptosis and affects DNA stainability.