Targeted cytokines for cancer immunotherapy

Targeting of cytokines into the tumor microenvironment using antibody-cytokine fusion proteins, called immunocytokines, represents a novel approach in cancer immunotherapy. This article summarizes therapeutic efficacy and immune mechanisms involved in targeting interleukin-2 (IL-2) to neuroectodermal, tumors using ganglioside GD2-specific antibody-IL-2 fusion protein (ch14.18-IL-2). Treatment of established melanoma metastases with ch14.18-IL-2 resulted in eradication of disease followed by a vaccination effect protecting mice from lethal challenges, with wild-type tumor calls. In a syngeneic neuroblastoma model, targeted IL-2 was effective in the amplification of a weak memory immune response previously induced by IL-12 gene therapy using an engineered linear version of this heterodimeric cytokine. These findings show that targeted IL-2 may provide an effective tool in cancer immunotherapy and establish the missing link between T cell-mediated, vaccination and objective clinical responses.     

The Diversity of Antigen-Specific TCR Repertoires Reflects the Relative Complexity of Epitopes Recognized

Antigen-selected T cell receptor (TCR) repertoires vary in complexity from very limited to extremely diverse. We have previously characterized two different CD8 T cell responses, which are restricted by the same mouse major histocompatibility complex (MHC) class I molecule, H-2 K^d. The TCR repertoire in the response against a determinant from Plasmodium berghei circumsporozoite protein (PbCS; region 252–260) is very diverse, whereas TCRs expressed by clones specific for a determinant in region 170–179 of HLA-CW3 (human) MHC class I molecule show relatively limited structural diversity. We had already demonstrated that cytolytic T lymphocyte (CTL) clones specific for the PbCS peptide display diverse patterns of antigen recognition when tested with a series of single Ala-substituted PbCS peptides or mutant H-2 K^d molecules. We now show that CW3-specific CTL clones display much less diverse patterns of recognition. Our earlier functional studies with synthetic peptide variants suggested that the optimal peptides recognized were 9 (or 8) residues long for PbCS and 10 residues long for CW3. We now present more direct evidence that the natural CW3 ligand is indeed a 10-mer. Our functional data together with molecular modeling suggest that the limited TCR repertoire selected during the CW3 response is not due to a paucity of available epitopes displayed at the surface of the CW3 peptide/K^d complex. We discuss other factors, such as the expression of similar self MHC peptide sequences, that might be involved in trimming this TCR repertoire.     

Pulmonary tuberculosis due to bacille Calmette-Guérin

Summary Immunotherapy using bacille Calmette-Guérin (BCG) has gained increasing acceptance in the management of superficial bladder cancer. Systemic reactions after intravesical instillation of BCG are rare. However, when the therapy is complicated, the lung often becomes involved. Since the pathogenesis of lung infiltrates after immunotherapy is unknown, we report on a patient who developed a lung infiltrate after receiving BCG immunotherapy for bladder cancer. The infectious etiology was established by culture confirmation of a BCG strain in the broncheoalveolar lavage fluid.Abbreviation BCG bacille Calmette-Guérin     

Estimating the relative frequency of leukodystrophies and recommendations for carrier screening in the era of next‐generation sequencing

Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A‐related leukodystrophy, Peroxisomal biogenesis disorders, POLR3‐related Leukodystrophy, Vanishing White Matter, and Pelizaeus‐Merzbacher Disease. Despite the relative frequency of these conditions, carrier‐screening laboratories regularly test only 20 of the 55 leukodystrophy‐related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.     

Evidence from twins for acquired cellular immune hyperactivity in type 1 diabetes

Type 1 diabetes has been associated with an increased frequency of activated T cells and T-cell hyperactivity to non-specific and disease-specific stimuli including the islet autoantigen glutamic acid decarboxylase 65 (GAD). To address whether T-cell hyperactivity is genetic or acquired we measured whole blood cytokines in vitro in response to GAD or tetanus in 18 identical twin pairs, nine discordant for type 1 diabetes. In addition, the activity of 2', 5' oligoadenylate synthetase (OAS) in blood mononuclear cells was measured as a marker of viral infection. Interleukin-2 (IL-2) basally and IL-2 and interferon-gamma (IFN-gamma) in response to GAD, were detected more frequently and at higher levels in diabetic compared to non-diabetic twins. IL-10 was not different between groups. OAS activity was increased in diabetic compared to non-diabetic twins and showed a correlation with basal IL-2 and GAD-stimulated IFN-gamma and IL-10. These findings suggest that T-cell hyperactivity in type 1 diabetes is an acquired trait and could reflect persisting virus expression.     

Prevalence of hepatitis B virus infection among women at reproductive age at a German university hospital

BACKGROUND: Mother to infant transmission of hepatitis B virus (HBV) represents a major factor in maintaining chronic infection and depends on the degree of maternal infectivity status. OBJECTIVES: To examine the seroprevalence of hepatitis B virus surface antigen (HBsAg) in women at reproductive age admitted to the Department of Gynaecology at a German university hospital. STUDY DESIGN: The seroprevalence of hepatitis B surface antigen (HBsAg) in 5518 women at reproductive age was examined, HBsAg-positive samples were tested for additional HBV markers to verify the infection status. RESULTS: Out of 5518 samples from women at reproductive age, 88 women (1.59%) were positive for HBsAg and 7 of these HBV-positive women (7.95%) were additionally positive for HBeAg. The majority of the study population were German citizens, however most HBV infected persons originated from countries with a high HBV prevalence. The HBV seroprevalence in our study group is about two times higher compared to the average seroprevalence in the German citizen adult population, thus probably resulting in an underestimation of the infection rate in a multinational setting. CONCLUSIONS: Screening for HBsAg during pregnancy is still necessary and important for reduction of perinatal HBV transmission even in countries with low HBV prevalence.     

Mosaicism in amniotic fluid cell cultures: Classification and significance

The last decade has witnessed increasing application of human cytogenetic technology to prenatal chromosome analysis. However, unlike the rather uniform peripheral blood T-lymphocyte system which has provided most of our experience in human cytogenetics, long-term amniotic-fluid cell cultures display extreme cellular heterogeneity and disproportionate growth of certain cell types as a consequence of clonal amplification. When they enter cell culture, many of these cells are approching the terminal stages of their respective life spans and may have accumulated chromosomal aberrations. Concern about the possibility of true fetal mosaicism seems warranted chiefly in situations were multiple colonies display potentially viable aberrations. Clonal analysis, preferable of multiple clonal types, and attention to details of clonal morphology are likely to minimize diagnostic errors and undue apprehension resulting from mosaicism in amniotic-fluid cell cultures.