Primary cold atmospheric plasma combined with low dose cisplatin as a possible adjuvant combination therapy for HNSCC cells-an in-vitro study.

BACKGROUND: The aim of the present study was to examine the cytostatic effects of cold atmospheric plasma (CAP) on different head and neck squamous carcinoma (HNSCC) cell lines either in isolation or in combination with low dose cisplatin. The effect of CAP treatment was investigated by using three different HNSCC cell lines (chemo-resistant Cal 27, chemo-sensitive FaDu and OSC 19). MATERIALS AND METHOD: Cell lines were exposed to CAP treatment for 30, 60, 90, 120 and 180 s (s). Cisplatin was added concurrently (cc) or 24 h after CAP application (cs). Cell viability, DNA damage and apoptosis was evaluated by dye exclusion, MTT, alkaline microgel electrophoresis assay and Annexin V-Fit-C/PI respectively. RESULTS: In all cell lines, 120 s of CAP exposure resulted in a significant reduction of cell viability. DNA damage significantly increased after 60 s. Combined treatment of cells with CAP and low dose cisplatin showed additive effects. A possible sensitivity to cisplatin could be restored in Cal 27 cells by CAP application. CONCLUSION: CAP shows strong cytostatic effects in HNSCC cell lines that can be increased by concurrent cisplatin treatment, suggesting that CAP may enhance the therapeutic efficacy of low dose cisplatin.

Cold Atmospheric Plasma Reduces Vessel Density and Increases Vascular Permeability and Apoptotic Cell Death in Solid Tumors.

Cold atmospheric plasma (CAP) has demonstrated promising anti-cancer effects in numerous in vitro and in vivo studies. Despite their relevance for the treatment of solid tumors, effects of CAP on tumor vasculature and microcirculation have only rarely been investigated. Here, we report the reduction of vessel density and an increase in vascular permeability and tumor cell apoptosis after CAP application. Solid tumors in the chorioallantoic membrane of chicken embryos were treated with CAP and evaluated with respect to effects of CAP on embryo survival, tumor size, and tumor morphology. Furthermore, intratumoral blood vessel density, apoptotic cell death and the tumor-associated microcirculation were investigated and compared to sham treatment. Treatment with CAP significantly reduced intratumoral vessel density while increasing the rate of intratumoral apoptosis in solid tumors. Furthermore, CAP treatment increased vascular permeability and attenuated the microcirculation by causing vessel occlusions in the tumor-associated vasculature. These effects point out the potential of CAP as a promising and yet underrated therapeutic modality for addressing the tumor vasculature in the treatment of solid tumors.

Quality of life in patients after reconstruction with the supraclavicular artery island flap (SCAIF) versus the radial free forearm flap (RFFF).

PURPOSE: Gold-standard for defect reconstruction in the head and neck region is the radial free forearm flap (RFFF). The supraclavicular artery island flap (SCAIF) gained popularity due to its versatility. Our objective was to compare functional advantages between both modalities. METHODS: A retrospective analysis of 24 consecutive cases with advanced-stage squamous cell cancer of the oral cavity and oropharynx after cancer defect reconstruction with two modalities (12 SCAIF; 12 RFFF) was conducted. Patients completed the European Organization for Research and Treatment of Cancer (EORTC) questionnaires, Quality of Life Questionnaire-Core 30-questions (QLQ-C30) and Quality of Life Questionnaire-Core 30 Head and Neck 35-questions (QLQ-H&N35). RESULTS: Mean follow-up was 22.2 ± 9.5 months. Comparison of quality of life (QOL) showed significant differences only in speech and problems with the senses in favor of the SCAIF. CONCLUSION: Patients report satisfactory QOL results after oncologic surgery and reconstruction with preliminary no significant differences in most aspects comparing the two modalities. Therefore, the SCAIF appears as a viable alternative to the gold standard, the RFFF.

Effects of cold atmospheric plasma (CAP) on bacteria and mucosa of the upper aerodigestive tract.

OBJECTIVE: Ear, nose and throat infections are among the most common reasons for absence from work. They are usually caused by various bacteria like Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes. Cold atmospheric plasma (CAP) can effectively eliminate even multi-resistant bacteria and has no cytotoxic or mutagenic effects on the mucosa when applied for less than 60s. Aim of the study was to evaluate the effects of CAP on common ENT bacteria and on the mucosa of the upper aerodigestive tract. METHODS: The bactericidal effects of CAP against the bacteria most commonly causing ENT infections were investigated using the colony-forming units assay (CFU) on a Müller-Hinton agar plate after applying CAP for 30, 60, 90 and 120s. To evaluate the interaction of CAP with mucosal cells, 3D mini organ cultures were treated for up to 180s, after which cell viability and necrosis induction were evaluated. RESULTS: Treatment with CAP for 60s or longer induced at least a 3-log10 reduction in the bacterial load (> 99.9%). Treatment times shorter than 60s had only slight cytotoxic effects on cell viability and necrosis whereas treatment times above 60s showed a fast increase of cytotoxic side effects. CONCLUSION: CAP exhibited strong bactericidal effects on the most common ENT pathogens. Treatment times of up to 60s showed only minimal adverse reactions in healthy mucosa. CAP could be a promising new therapeutic modality for ENT infections.

Shoulder Morbidity in Patients after Head and Neck Reconstruction with the Pedicled Supraclavicular Island Flap.

BACKGROUND: The pedicled supraclavicular artery island flap (SCAIF) for reconstruction of the head and neck has been shown to be a pliable alternative to established pedicled flaps, such as the pectoralis major myocutaneous flap. Because there are limited published data regarding shoulder morbidity after SCAIF procedure, we aimed to investigate it with 2 established questionnaires for the upper extremity [Constant-Murley score and Disabilities of the Arm, Shoulder and Hand Outcome Measure (DASH) score]. METHODS: The authors designed and implemented a retrospective cohort study of patients who received a defect reconstruction by SCAIF. Analyzed parameters were demographics, comorbidities, donor-site morbidity and shoulder morbidity in terms of range of motion, pain, strength, and daily activities evaluated and compared between the donor site and contralateral arm. RESULTS: Of the 61 consecutively performed head and neck reconstructions with SCAIF, 20 met inclusion criteria (curative intended treatment, head and neck squamous cell cancer, follow-up time more than 4 months). Mean follow-up was 17.3 months (±10.4 months) ranging from 4-35 months. Donor-site complication rate was low with 5% major (surgical revision) and 30% minor complications (conservative management). Overall Constant-Murley-Score (P = 0.334), pain (P = 0.150), overall range of motion (P = 0.861), and strength of the extremity (P = 0.638) of the shoulder receiving a SCAIF showed no significant differences to the contralateral extremity. Mean of Disabilities of the Arm, Shoulder and Hand Outcome Measure score was 32.5 (±28.6). CONCLUSION: The results of the present study suggest very low shoulder morbidity in patients after SCAIF procedure with no significant functional impairment of the donor shoulder compared with the contralateral side.

Therapy Testing in a Spheroid-based 3D Cell Culture Model for Head and Neck Squamous Cell Carcinoma.

Current treatment options for advanced and recurrent head and neck squamous cell carcinoma (HNSCC) enclose radiation and chemo-radiation approaches with or without surgery. While platinum-based chemotherapy regimens currently represent the gold standard in terms of efficacy and are given in the vast majority of cases, new chemotherapy regimens, namely immunotherapy are emerging. However, the response rates and therapy resistance mechanisms for either chemo regimen are hard to predict and remain insufficiently understood. Broad variations of chemo and radiation resistance mechanisms are known to date. This study describes the development of a standardized, high-throughput in vitro assay to assess HNSCC cell line's response to various therapy regimens, and hopefully on primary cells from individual patients as a future tool for personalized tumor therapy. The assay is designed to being integrated into the quality-controlled standard algorithm for HNSCC patients at our tertiary care center; however, this will be subject of future studies. Technical feasibility looks promising for primary cells from tumor biopsies from actual patients. Specimens are then transferred into the laboratory. Biopsies are mechanically separated followed by enzymatic digestion. Cells are then cultured in ultra-low adhesion cell culture vials that promote the reproducible, standardized and spontaneous formation of three-dimensional, spheroid-shaped cell conglomerates. Spheroids are then ready to be exposed to chemo-radiation protocols and immunotherapy protocols as needed. The final cell viability and spheroid size are indicators of therapy susceptibility and therefore could be drawn into consideration in future to assess the patients' likely therapy response. This model could be a valuable, cost-efficient tool towards personalized therapy for head and neck cancer.

Evaluation of margins in head and neck squamous cell carcinoma from the surgeon's perspective.

BACKGROUND: The surgeon's evaluation of resection status based on frozen section analysis during operation and pathological examination of resected specimens often differ. For this study, we recapitulated the surgeon's perspective during an operation, accordingly classified the evaluation of margins by the surgeon, and analyzed its impact on the outcome compared with the pathological results. METHODS: This was a retrospective analysis. As data sources, paper-based and digital patient files, as well as the Munich Cancer Registry database were used. RESULTS: Three hundred ninety-six cases were included in this analysis. Only the evaluation of margins by the surgeon influenced local control, and the pathological results influenced disease-free survival (DFS). Surprisingly, margins of >5 mm of normal tissue to cancer growth led to local control and overall survival (OS) significantly worse than 1 to 5-mm resections. CONCLUSION: The evaluation of margins by the surgeon is of significant importance for local control and OS. It is largely based on frozen section analysis, which, therefore, should be used whenever possible.

Is Perineural Invasion of Head and Neck Squamous Cell Carcinomas Linked to Tobacco Consumption?

Perineural invasion (PNI) is an underrecognized path of cancer spread, and its causes and mechanisms are poorly understood. Recent research indicates a mutual attraction of neuronal and cancer cells, largely dependent on neurotrophic factors and their receptors. Interestingly, the release of neurotrophic factors occurs upon cigarette smoke/nicotine exposure in a dose-dependent manner, and serum levels correlate with current smoking, number of smoking years, and smoking severity. Among cell types capable of neurotrophic factors secretion are lung and oral fibroblasts. In our study of 178 patients with head and neck squamous cell carcinoma, tumors of current and former smokers showed PNI significantly more often than tumors of never smokers. Moreover, PNI was a marker for aggressive tumor growth. Surprisingly, PNI was more significant for survival than p16 status. Our study warrants further research on PNI in head and neck squamous cell carcinoma with special emphasis on the impact of tobacco consumption to identify suitable candidates for therapeutic interventions.

Spheroid-based 3D Cell Cultures Enable Personalized Therapy Testing and Drug Discovery in Head and Neck Cancer.

BACKGROUND/AIM: Chemo-radiation currently serves as first-line therapy of advanced and recurrent head and neck cancer, while new chemotherapy regimens are emerging. However, response rates to any treatment are difficult to predict and underlie broad variation. This study shows the development of a standardized, high-throughput in vitro assay to assess patients' individual response to therapy regimens as a future tool for personalized tumor therapy. MATERIALS AND METHODS: Viability and proliferation analyses after chemo +/- radiation treatment of single spheroids (low adhesion plates/Hanging Drop (HD)) were generated from head and neck squamous cell carcinoma (HNSCC) cell lines and primary human cells from fresh tumor specimens. RESULTS: All cell lines showed reliable growth in all cell culture methods. The spheroids showed significant delay of growth and/or necrosis compared to control groups when exposed to current standard chemotherapeutic regimens. Single 3D spheroids ready for therapy susceptibility testing could be generated from actual tumor specimens after enzymatic and mechanical separation. CONCLUSION: In its current form, this single spheroid-based in vitro assay was able to test individual therapy susceptibility to current standard therapy regimens or, potentially, for testing new targeted drugs in HNSCC treatment. With recent discoveries regarding tumor heterogeneity and individual mutation status, a reliable assay is a prerequisite for personalized therapy in head and neck cancer.

Transoral laser microsurgery for treatment for hypopharyngeal cancer in 211 patients.

BACKGROUND: The oncologic and functional outcome of transoral laser microsurgery (TLM) for primary treatment of hypopharyngeal cancer was examined in a multimodal treatment concept. METHODS: Two hundred eleven patients with squamous cell carcinoma (SCC) of the hypopharynx (pT1-4a, pN0-2, M0) were treated by TLM +/- neck dissection (88%) +/- (chemo)radiotherapy ([C]RT; 51%). The majority of cases were advanced stages III and IVa (85%). RESULTS: The 5-year Kaplan-Meier estimates for local control after TLM were pT category-related 88.1%, 74.8%, 77.3%, and 61.8% for pT1-4a tumors. The 5-year estimates of overall survival (OS), disease-specific survival (DSS), and recurrence-free survival (RFS) for early stages I and II were 68.2%, 96.7%, and 74.6%, respectively; for stage III they were 65.9%, 83.8%, and 56.4%, respectively; and the rates for stage IVa were 44.5%, 60.7%, and 50.3%, respectively. Overall, 95.7% of the patients maintained regular oral nutrition without feeding tube dependency. CONCLUSION: Primary TLM in multimodal concepts of treatment (+/- neck dissection, +/- [C]RT) offers favorable oncologic results as compared with other therapeutic regimes.

Oral Cancer Reconstruction Using the Supraclavicular Artery Island Flap: Comparison to Free Radial Forearm Flap.

PURPOSE: To evaluate whether the pedicled supraclavicular artery island flap (SCAIF) is a sufficient alternative to the fasciocutaneous radial forearm free flap (RFFF) for oral reconstruction in cancer surgery. PATIENTS AND METHODS: The authors designed and implemented a retrospective cohort study composed of all consecutive patients who underwent head and neck reconstruction after cancer surgery at their tertiary university hospital from 2013 to 2016. Demographics and peri- and postoperative information were recorded and statistically analyzed. RESULTS: Of 83 patients who underwent head and neck reconstruction after cancer, 50 were identified as having stage III or IV squamous cell carcinoma of the oral cavity and oropharynx and underwent surgery and reconstruction with the SCAIF (n = 25) or the RFFF (n = 25). Total surgery time (411.0 vs 576.4 minutes; P < .001), flap elevation time (39.00 vs 93.78 minutes; P < .001), need for intensive care observation (32 vs 96%; P < .05), and rate of tracheotomy (64 vs 88%; P < .05) were significantly lower in the SCAIF group. There was no statistical difference in the postoperative complication rate or postoperative functional swallowing ability between the 2 groups. Total perioperative costs were significantly lower in patients who underwent reconstruction with the SCAIF (2,621.15 vs 4,453.77€; P < .01). CONCLUSION: The results of this study suggest that the SCAIF is a straightforward and reliable flap with shorter operative times and comparable outcomes compared with the RFFF.

Transoral laser microsurgery for T1b glottic cancer: review of 51 cases.

For the treatment of T1b glottic carcinoma, different treatment options, such as transoral laser microsurgery, open surgical techniques, and primary radiotherapy, are under discussion. In this context, the aim of the present study was to describe oncologic results and complication rates of transoral laser microsurgery in treatment of T1b glottic carcinoma. This is a retrospective unicenter chart review of patients treated at an academic tertiary referral center between 1986 and 2006. Fifty-one previously untreated T1b cases were exclusively treated by transoral laser microsurgery and included into this study, 47 were male, and 4 were female. The main outcome measures included local control rate and complications, overall, disease specific, and recurrence-free survival. The median follow-up period was 98 months. The 5-year local control rate was 90.2%; larynx preservation rate was 92.2%. No intra- or postoperative complications, such as wound infections, postoperative bleeding, hematoma, edema, and fistula development, were observed. A single patient required revision surgery due to synechia. Five-year survival rates were: overall 84.7%, disease specific 97.7%, and recurrence free 72.4%. Our data support the conclusion that transoral laser microsurgery is a considerable treatment option in T1b glottic carcinoma. The oncologic outcome was at least comparable to other treatment options, while the perioperative morbidity and complication rate were lower.

Cytotoxic and Genotoxic Effects of Electronic Cigarette Liquids on Human Mucosal Tissue Cultures of the Oropharynx.

The popularity of electronic cigarettes (ECs) is rapidly growing and ECs are claimed to be an uncritically regarded alternative to conventional cigarettes. The mucosal tissue of the upper aerodigestive tract (UADT) is the first contact organ for xenobiotics such as liquids of ECs. The aim of this study is to investigate the bimolecular effects of e-liquids on human pharyngeal tissue cultures to evaluate whether e-liquids and their components present a risk factor for head and neck squamous cell carcinoma. Fresh tissue samples of healthy oropharyngeal mucosa were assembled into mucosal tissue cultures. Two fruit-flavored liquids (FLs), one tobacco-flavored liquid (TL) (all containing nicotine), and the corresponding base mixtures (free of nicotine and flavor) were used in three different dilutions. Cytotoxicity was assessed using the water-soluble tetrazolium-8 assay. DNA fragmentation was quantified using alkaline microgel electrophoresis. All liquids caused a significant reduction in cell viability. FLs especially showed a higher toxicity than TL. DNA fragmentation significantly increased by incubation with FL, whereas treatment with TL did not show serious DNA damage. E-liquids are cytotoxic to oropharyngeal tissue, and some liquids can induce relevant DNA damage. Thus, mutagenicity for mucosa of the UADT and e-liquids as risk factors for head and neck cancer cannot entirely be ruled out. Only the implementation of standards and regulations for liquid production and distribution can ensure a valid scientific investigation and assessment of carcinogenic potential of long-term EC use.

The Prediction of Speech Recognition in Noise With a Semi-Implantable Bone Conduction Hearing System by External Bone Conduction Stimulation With Headband: A Prospective Study.

Semi-implantable transcutaneous bone conduction devices are treatment options for conductive and mixed hearing loss (CHL/MHL). For counseling of patients, realistic simulation of the functional result is desirable. This study compared speech recognition in noise with a semi-implantable transcutaneous bone conduction device to external stimulation with a bone conduction device fixed by a headband. Eight German-language adult patients were enrolled after a semi-implantable transcutaneous bone conduction device (Bonebridge, Med-El) was implanted and fitted. Patients received a bone conduction device for external stimulation (Baha BP110, Cochlear) fixed by a headband for comparison. The main outcome measure was speech recognition in noise (Oldenburg Sentence Test). Pure-tone audiometry was performed and subjective benefit was assessed using the Glasgow Benefit Inventory and Abbreviated Profile of Hearing Aid Benefit questionnaires. Unaided, patients showed a mean signal-to-noise ratio threshold of 4.6 ± 4.2 dB S/N for speech recognition. The aided results were -3.3 ± 7.2 dB S/N by external bone conduction stimulation and -1.2 ± 4.0 dB S/N by the semi-implantable bone conduction device. The difference between the two devices was not statistically significant, while the difference was significant between unaided and aided situation for both devices. Both questionnaires for subjective benefit favored the semi-implantable device over external stimulation. We conclude that it is possible to simulate the result of speech recognition in noise with a semi-implantable transcutaneous bone conduction device by external stimulation. This should be part of preoperative counseling of patients with CHL/MHL before implantation of a bone conduction device.

(Chemo)radiotherapy after laser microsurgery and selective neck dissection for pN2 head and neck cancer.

This study analyzed the efficacy of transoral laser microsurgery and postoperative (chemo) radiotherapy (CRT) for head and neck squamous cell carcinoma. Between 1987 and 2007, 318 patients with pN2 neck disease were included. Seventy-three patients received laser resection and neck dissection alone, 154 postoperative radiotherapy, and 91 postoperative (C)RT. Mean follow-up was 58.2 ± 51.2 months, and locoregional control was significantly better after postoperative (C)RT (surgery alone: 42 %, radiotherapy: 57 %, CRT: 59 %; p < 0.01). Postoperative (C)RT did not have a significant impact on disease-specific survival (DSS) (surgery alone: 55 %, radiotherapy alone: 60 %, CRT: 64 %; p = 0.36). Fifty-seven patients (17.92 %) developed distant metastases, and 39 patients (12.26 %) presented with secondary malignancies, with no significant differences found between the treatment groups. Postoperative (C)RT significantly improved locoregional control, but had no significant effect on DSS because of high rates of secondary malignancies and distant metastases. Reduced radicality in combination with an effective screening might improve prognosis and quality of life of these patients.

Cold Atmospheric Plasma: A Promising Complementary Therapy for Squamous Head and Neck Cancer.

Head and neck squamous cell cancer (HNSCC) is the 7th most common cancer worldwide. Despite the development of new therapeutic agents such as monoclonal antibodies, prognosis did not change for the last decades. Cold atmospheric plasma (CAP) presents the most promising new technology in cancer treatment. In this study the efficacy of a surface micro discharging (SMD) plasma device against two head and neck cancer cell lines was proved. Effects on the cell viability, DNA fragmentation and apoptosis induction were evaluated with the MTT assay, alkaline microgel electrophoresis (comet assay) and Annexin-V/PI staining. MTT assay revealed that the CAP treatment markedly decreases the cell viability for all tested treatment times (30, 60, 90, 120 and 180 s). IC 50 was reached within maximal 120 seconds of CAP treatment. Comet assay analysis showed a dose dependent high DNA fragmentation being one of the key players in anti-cancer activity of CAP. Annexin-V/PI staining revealed induction of apoptosis in CAP treated HNSCC cell lines but no significant dose dependency was seen. Thus, we confirmed that SMD Plasma technology is definitely a promising new approach on cancer treatment.

Surgically treated oropharyngeal cancer: risk factors and tumor characteristics.

PURPOSE: To assess risk factors of patients with oropharyngeal squamous cell carcinoma in the Munich area of Southern Germany in relation to human papillomavirus (HPV) association of the tumors. To demonstrate differences in tumor characteristics and their impact on adjuvant treatment. METHODS: Between November 2010 and July 2013, patients were prospectively interviewed for risk factors before they underwent surgical resection of their tumors. HPV association was evaluated by p16 immunohistochemistry; tumor characteristics and type of adjuvant treatment were recorded. Follow-up data were collected after a median follow-up of 12.1 month. RESULTS: In contrast to many recent studies, we could not detect any difference in overall age and age at sexual debut between p16-positive and p16-negative patients. P16-negative patients are characterized by a more intensive tobacco and alcohol use, a more abusive way of consumption, less nonoral and less oral sex partners. P16-positive patients had a significantly higher risk of lymph node metastases, but nevertheless a significant lower risk to recur or to die. No difference in the incidence of synchronous second primary tumors was seen. P16-positive patients generally received a more aggressive adjuvant treatment because of more frequently involved lymph nodes. CONCLUSION: Lifestyle risk factors such as smoking, drinking, and sexual habits were independent from age, but showed marked differences between the p16-positive and p16-negative group. Since p16-positive patients were treated more aggressively, it is not possible to distinguish whether the better outcome of HPV-positive patients is a result of less aggressive cancers or more aggressive treatment. With regard to the ongoing debate about treatment deintensification, we should keep in mind that the survival of HPV-positive cancer patients is not 100 %.

Restoration of sensitivity in chemo-resistant glioma cells by cold atmospheric plasma.

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. Despite multimodal treatments including surgery, chemotherapy and radiotherapy the prognosis remains poor and relapse occurs regularly. The alkylating agent temozolomide (TMZ) has been shown to improve the overall survival in patients with malignant gliomas, especially in tumors with methylated promoter of the O6-methylguanine-DNA-methyltransferase (MGMT) gene. However, intrinsic and acquired resistance towards TMZ makes it crucial to find new therapeutic strategies aimed at improving the prognosis of patients suffering from malignant gliomas. Cold atmospheric plasma is a new auspicious candidate in cancer treatment. In the present study we demonstrate the anti-cancer properties of different dosages of cold atmospheric plasma (CAP) both in TMZ-sensitive and TMZ-resistant cells by proliferation assay, immunoblotting, cell cycle analysis, and clonogenicity assay. Importantly, CAP treatment restored the responsiveness of resistant glioma cells towards TMZ therapy. Concomitant treatment with CAP and TMZ led to inhibition of cell growth and cell cycle arrest, thus CAP might be a promising candidate for combination therapy especially for patients suffering from GBMs showing an unfavorable MGMT status and TMZ resistance.

IgE reactivity profiles among house dust mite allergic patients in Bavaria.

Recombinant allergen diagnostics have become increasingly important in daily allergological routine, made possible by inroads into the understanding of major and minor allergens accomplished within the last decade. Recombinant allergen diagnostics will, however, only provide correct diagnoses when sufficient knowledge of the regional IgE reactivity profile to a specific allergen source is available. A variety of studies in different European countries revealed reactivity profiles, where a sensitization to house dust mite could be recognized in more than 97 % of cases in which Der p1 and Der p2 were measured. The aim of this study was to investigate the IgE reactivity profiles of house dust mite allergic patients in southern Germany. Sera of house dust mite allergic patients (positive intranasal provocation) were screened for IgE antibodies against commercially available D pter., nDer p1, rDer p2 and rDer p10. IgE antibodies against D pter. could be found in 98 out of 98 sera (100 %). Seventy-five patients (76.5 %) reacted to nDer p1. In 72 patients (73.4 %), IgE antibodies against rDer p2 could be found, while IgE antibodies against rDer p10 were present in only 4 patients (4.1 %). Seventeen patients (17.3 %) had no IgE antibodies against nDer p1, rDer p2 and nDer p10, but displayed reactions to D pter. Knowledge of IgE regional reactivity profiles is necessary when using recombinant allergen diagnostics. In the case of our house dust mite allergic patients 17 would have remained undiagnosed based on a diagnostic method utilizing only the two major allergens nDerp1 and rDerp2.