Glycan engineering reveals interrelated effects of terminal galactose and core fucose on antibody-dependent cell-mediated cytotoxicity

Antibody-dependent cell-mediated cytotoxicity (ADCC) has been identified as one of the potentially critical effector functions underlying the clinical efficacy of some therapeutic immunoglobin G1 (IgG1) antibodies. It has been well established that higher levels of afucosylated N-linked glycan structures on the Fc region enhance the IgG binding affinity to the FcγIIIa receptor and lead to increased ADCC activity. However, whether terminal galactosylation of an IgG1 impacts its ADCC activity is less understood. Here, we used a new strategy for glycan enrichment and remodeling to study the impact of terminal galactose on ADCC activity for therapeutic IgG1s. Our results indicate that the degree of influence of terminal galactose on in vitro ADCC activity depends on the presence or absence of the core fucose, which is typically linked to the first N-acetyl glucosamine residue of an N-linked glycosylation core structure. Specifically, terminal galactose on afucosylated IgG1 mAbs enhanced ADCC activity with impact coefficients (ADCC%/Gal%) more than 20, but had minimal influence on ADCC activity on fucosylated structures with impact coefficient in the range of 0.1–0.2. Knowledge gained here can be used to guide product and process development activities for biotherapeutic antibodies that require effector function for efficacy, and also highlight the complexity in modulating the immune response through N-linked glycosylation of antibodies.     

Density of epidermal Langerhans cells in psoriasis patients treated with an aromatic retinoid (RO 10-9359). An immunoperoxidase study using anti-T6 and anti-Ia monoclonal antibodies

Immunocytochemical techniques using antibodies to the specific T6 and Ia (Major Histocompatibility Complex, class II, human HLA-Dr) antigens were used to determine the densities of epidermal Langerhans cells (LC) in psoriasis patients treated with the aromatic retinoid RO 10-9359. Fourteen patients were treated with the aromatic retinoid and were skin biopsied before, during and after therapy. Two psoriasis patients receiving PUVA (systemic 8-methoxypsoralen + UVA irradiation) were included in the study. The results showed an increase in LC numbers during aromatic retinoid administration, which coincided with an improvement in the clinical severity of the lesions. At the end of retinoid administration the LC numbers were similar to those found in the initial psoriatic plaques. The density of Ia+ LC, in comparison with T6+ LC in the epidermis of psoriatic plaques were significantly different. Dendritic and non-dendritic Ia+ cells were also observed in the dermis of the plaques. Unlike aromatic retinoid treated patients, PUVA treated patients showed a decrease of both T6+ and Ia+ epidermal LC by the middle of therapy, a total absence of immunoreaction by the end of therapy, and a return to normal skin values a few weeks after treatment. This immunocytochemical study helps in distinguishing between dendritic and other possible Ia-expressing cells from the infiltrate that may penetrate the epithelium. These results do not conclusively demonstrate the role of LC in the pathogenesis of psoriasis. Other factors, such as the interrelationship with other immune response cell types and alterations in the lymphokine cascade may be important.     

Lymphocyte subpopulations in malignant ascites of serous papillary ovarian adenocarcinoma. An immunocytochemical study

The aim of this study was to investigate lymphocyte subpopulations in 17 patients with malignant ascites due to serous papillary adenocarcinoma of the ovary. Eight patients had not been treated prior to the study whereas nine patients had been treated by surgery and chemotherapy. A panel of monoclonal antibodies against surface markers that correlate with the immune functions of the lymphocytes was used. The lymphocyte subpopulations were identified by the immunoperoxidase adhesive slide assay, and the results in treated and untreated patients were compared. Both groups of patients showed lymphocytosis (41 +/- 25% and 33 +/- 14% of the total cells, respectively). The untreated patients had a significantly higher proportion of B cells (14 +/- 4% of lymphocytes) than did treated patients (7 +/- 2%). No differences were found between both groups regarding the helper-inducer/suppressor-cytotoxic T lymphocyte ratio. The proportion of lymphocytes expressing interleukin-2-receptors was higher in treated patients (6 +/- 2%) than in untreated patients (1.2 +/- 1%). Both groups showed a high percentage of natural killer/cytotoxic cells (17 +/- 7% and 18 +/- 5%, respectively). In the only chylous effusion in this study, there was an increase in helper-inducer and activated T lymphocytes. Future studies are required to document whether surface marker analysis of lymphocytes in malignant effusions may be useful for assessment of the prognosis and the results of treatment.     

Clinical and biochemical changes in 53 Swedish dogs bitten by the European adder - <Emphasis Type="Italic">Vipera berus</Emphasis>

Background  

Every year many dogs in Sweden are bitten by Vipera berus, the only venomous viper in Sweden. This prospective study investigated clinical signs, some biochemical parameters, treatment, and progress of disease after snakebite in 53 dogs. Effects of treatment with and without glucocorticoids were evaluated.