Enhancement of human papilloma virus type 16 E7 specific T cell responses by local invasive procedures in patients with (pre)malignant cervical neoplasia

It has been suggested that local invasive procedures may alter the natural course of (pre)malignant cervical disease. This could be due to partial excision of the lesions, or via induction of cellular immunity against human papillomavirus (HPV) by the local invasive procedures. We studied the influence of local invasive procedures on HPV-16 E7 specific immune responses in patients with different grades of cervical intra-epithelial neoplasia (CIN) and different stages of cervical cancer. Blood was obtained at intake and after invasive procedures from patients with CIN or cervical cancer. Antigen specific T-cell responses were measured by IFN-gamma ELISPOT analysis, after stimulation with recombinant HPV-16 E7 protein. As expected, HPV-16 E7 specific IFN-gamma T cell responses were more frequent in HPV-16 DNA positive patients compared with that in HPV-16 DNA negative patients (39/50 vs. 16/36, (p=0.006, chi2 test). After invasive procedures, a small number of HPV-16 DNA positive CIN patients, but a considerable proportion of HPV-16 DNA positive cervical cancer patients, showed an enhancement of T cell responses against HPV-16 E7. Induction of T cell reactivity was most pronounced in cervical cancer patients who had undergone previous invasive procedures. Both CD4+ and CD8+ T cells showed E7 specific IFN-gamma production upon in-vitro stimulation. Our study shows that invasive procedures may enhance HPV-specific cell-mediated immunity in a considerable number of patients with cervical cancer, but in only a minority of CIN patients. Our data indicate that invasive procedures should be considered as possible confounding factors when analyzing the effectiveness of therapeutic immunization studies, especially, when induction of HPV-specific immune responses is used as intermediate end-point.

A new phosphospecific cell-based ELISA for p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK, protein kinase B and cAMP-response-element-binding protein

Assaying activation of signal transduction is laborious and does not allow the study of large numbers of samples, essential for high-throughput drug screens or for large groups of patients. Using phosphospecific antibodies, we have developed ELISA techniques enabling non-radioactive semi-quantitative assessment of the activation state of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK, protein kinase B and the transcription factor cAMP-response-element-binding protein (CREB) in 96-well plates. This assay has been termed PACE (phosphospecific antibody cell-based ELISA) and was used successfully for both adherent and suspension cells. Various stimuli induced dose-dependent enzymic activity of which the kinetics closely correlated with those measured via classical methodology. Using PACE we have now characterized for the first time the concentration-dependent effects of various inflammatory prostaglandins on CREB phosphorylation in macrophages. PACE is a straightforward and novel technique enabling the large-scale analysis of signal transduction.

A critical role for PI 3-kinase in cytokine-induced Fcalpha-receptor activation

Fc-receptors, such as FcalphaR and FcgammaRII, play an important role in leukocyte activation, and rapid modulation of ligand binding ("activation") is critical for receptor regulation. We have previously demonstrated that ligand binding to Fc-receptors on human eosinophils is dependent on cytokine stimulation. Utilization of pharmacological inhibitors provided evidence that the phenomenon of interleukin (IL)-5 induced immunoglobulin A (IgA) binding to human eosinophils requires activation of phosphatidylinositol 3-kinase (PI3K). However, eosinophils are refractory to manipulation by molecular techniques such as DNA transfection or viral infection. Here we utilize an IL-3 dependent pre-B cell line to investigate the molecular mechanism of cytokine-mediated ligand binding to FcalphaR. In this system, IgA binding is dependent on IL-3, similarly to the requirement for IL-5 of eosinophils. We show that IL-3-mediated activation of FcalphaR (CD89) requires the activation of PI3K, independent of p21ras activation. Co-expression of dominant negative (triangle upp85) and active (p110_K227E) forms of PI3K demonstrate that the affinity switch regulating FcalphaR activation requires PI3K. Moreover, overexpression of PI3K is both necessary and sufficient for activation of FcalphaR. Furthermore, we show that IL-3/IL-5/GM-CSF induced inside-out signaling pathways activating FcalphaR require the involvement of protein kinase C downstream of PI3K. Finally, we show that these inside-out signaling pathways responsible for Fcalpha-receptor modulation require CD89, independent of its association with the FcRgamma chain. (Blood. 2000;95:2037-2043)

Decreased sensitivity to dexamethasone in lymphocytes from patients with Alzheimer's disease

Cortisol levels in patients with Alzheimer's disease (AD) are relatively unaffected by a challenge with dexamethasone (DEX) in vivo. The present study demonstrates that DEX is less inhibitory for phytohemagglutinin (PHA)-induced T cell proliferation in AD patients as compared to age-matched controls. Since no significant differences were found between AD patients and age-matched controls with regard to the fraction of CD45RA+ or CD45RO+ CD4+ T cells nor the ability of peripheral blood mononuclear cells to produce IL-2 or IL-4, it is unlikely that the difference in DEX sensitivity is due to a changed lymphokine profile or a changed composition of the CD4+ T cell population. Sensitivity to DEX was negatively correlated with the ability to produce IL-2 and IL-4 in the controls but not in AD patients. This suggests that IL-2 and IL-4 synthesis in AD patients is less sensitive to regulation by glucocorticoids.