Monoclonal antibody U36, a suitable candidate for clinical immunotherapy of squamous-cell carcinoma,recognizes a CD44 isoform

At present, tumor-targeting with monoclonal antibodies (MAbs) is among the most promising novel adjuvant-therapy modalities for the treatment of patients with minimal residual disease of head-and-neck squamous-cell carcinoma (HNSCC). For this purpose we developed MAb U36, recognizing a 200-kDa antigen expressed on the outer cell surface of squamous-cell carcinomas and their normal counterparts. Clinical radioimmunoscintigraphy (RIS) and biodistribution studies have shown that the MAb-U36-defined antigen is a suitable target molecule for antibody-based therapy of head-and-neck cancer. In the present study we further characterized the antigen by cDNA cloning. The cDNA was isolated by expression cloning in COS-7 cells. Sequence analysis and database searching revealed that the MAb-U36-defined antigen is identical to the squamous-cell-specific CD44 splice variant epican. The epitope recognized by MAb U36 was mapped by screening overlapping synthetic peptides of the epican-specific region encoded by exon 7–11 (v3–v7), and appeared to be located in the v6 domain. The applicability of MAb U36 for targeting human tumors of various origin expressing the CD44v6 domain is discussed. © 1996 Wiley-Liss, Inc.     

In Vivo Imaging of Enhanced Leukocyte Accumulation in Atherosclerotic Lesions in Humans

Background

Understanding how leukocytes impact atherogenesis contributes critically to our concept of atherosclerosis development and the identification of potential therapeutic targets.

Objectives

The study evaluates an in vivo imaging approach to visualize peripheral blood mononuclear cell (PBMC) accumulation in atherosclerotic lesions of cardiovascular (CV) patients using hybrid single-photon emission computed tomography/computed tomography (SPECT/CT).

Methods

At baseline, CV patients and healthy controls underwent ¹⁸fluorodeoxyglucose positron emission tomography-computed tomography and magnetic resonance imaging to assess arterial wall inflammation and dimensions, respectively. For in vivo trafficking, autologous PBMCs were isolated, labeled with technetium-99m, and visualized 3, 4.5, and 6 h post-infusion with SPECT/CT.

Results

Ten CV patients and 5 healthy controls were included. Patients had an increased arterial wall inflammation (target-to-background ratio [TBR] right carotid 2.00 ± 0.26 in patients vs. 1.51 ± 0.12 in controls; p = 0.022) and atherosclerotic burden (normalized wall index 0.52 ± 0.09 in patients vs. 0.33 ± 0.02 in controls; p = 0.026). Elevated PBMC accumulation in the arterial wall was observed in patients; for the right carotid, the arterial-wall-to-blood ratio (ABR) 4.5 h post-infusion was 2.13 ± 0.35 in patients versus 1.49 ± 0.40 in controls (p = 0.038). In patients, the ABR correlated with the TBR of the corresponding vessel (for the right carotid: r = 0.88; p < 0.001).

Conclusions

PBMC accumulation is markedly enhanced in patients with advanced atherosclerotic lesions and correlates with disease severity. This study provides a noninvasive imaging tool to validate the development and implementation of interventions targeting leukocytes in atherosclerosis.     

Magnetic resonance imaging of the heart for determination of ejection fraction

In 28 patients with various cardiac diseases we compared ejection fractions obtained by magnetic resonance imaging in a single oblique slice with monoplane ventriculography in the right anterior oblique projection, the latter serving as the standard. Also, results were evaluated for clinical relevance and relation to image quality. The correlation between the two techniques was moderate (r = 0.65). According to our standardized limits for clinical relevance, insufficiently correlating ejection fractions were obtained in 14 patients. In 8 of these patients this was attributed to poor endocardial edge detection. Edge detection problems were more frequently encountered by imaging with echo-time 20 msec than with echo-time 32 msec. Other causes for mismatching of the obtained ejection fractions are discussed. It is concluded that determination of ejection fraction by single slice magnetic resonance imaging should not be used for clinical application. Improvement can be expected by using a contiguous slicing technique, a longer echo-time in the spin-echo pulse sequence, or in due course by application of newly developed fast-imaging pulse sequences.     

The effects of topical corticosteroids and a coal tar preparation on dithranol-induced irritation in patients with psoriasis

Dithranol has been a mainstay in the treatment of psoriasis for more than 80 years. Although a safe approach, the irritation of the clinically uninvolved perilesional skin remains a major limitation of this treatment. Corticosteroids and coal tar solution have an anti-inflammatory potential. The aim of the present study was to investigate the clinical and cell-biological effects of two topical corticosteroids and a coal tar preparation on dithranol-irritated skin. During 4 consecutive days, 2% dithranol cream was applied to six uninvolved skin sites (3 cm in diameter) on the lower back of 9 patients with psoriasis. Dithranol was left on the skin for 1 h, subsequently removed with water and soap and the skin was dried with a towel. Subsequently, SITE 1 was treated with 0.05% clobetasol-17-propionate ointment (CP), SITE 2 with unguentum cetomacrogolis (vehicle 1), SITE 3 with 0.005% fluticasonpropionate ointment (FP), SITE 4 with 10% coal tar solution in lanettewax cream (CTS), SITE 5 was left untreated (control) and SITE 6 was treated with lanettewax cream (vehicle 2). Erythema, oedema and vesicle formation was scored every day. On day 5, punch biopsies were taken from the six sites. The expression of epidermal proliferation, differentiation and inflammation markers and the clinical irritation scores indicate that the application of a high potency corticosteroid (CP) is the best approach to minimise dithranol irritation, whereas CTS had virtually no effect on dithranol irritation during this 4-day experimental model.     

CTLA-4 up-regulation of lymphocyte function-associated antigen 1 adhesion and clustering as an alternate basis for coreceptor function

Although cytotoxic T lymphocyte antigen-4 (CTLA-4) negatively regulates T cell activation, the full range of functions mediated by this coreceptor has yet to be established. In this study, we report the surprising finding that CTLA-4 engagement by soluble antibody or CD80 potently up-regulates lymphocyte function-associated antigen 1 (LFA-1) adhesion to intercellular adhesion molecule-1 (ICAM-1) and receptor clustering concurrent with IL-2 inhibition. This effect was also observed with CTLA-4 ligation and not with other coreceptors. T cell antigen receptor (TcR)-induced lymphocyte function-associated antigen 1 function was also dependent on CTLA-4 expression as observed with reduced adhesion/clustering on CTLA-4(-/-) primary T cells. CTLA-4 up-regulated adhesion was mediated by regulator for cell adhesion and polarization type 1 (Rap-1) as shown by anti-CTLA-4-induced Rap-1 activation as well as Rap-1-N17 blockade and Rap-1-V12 mimicry of adhesion/clustering. Our findings identify a potent role for CTLA-4 in directing integrin adhesion and provide an alternate mechanism to account for aspects of CTLA-4 function in T cell immunity.