[A retrospective study of postoperative adjuvant therapy following immunotherapy combined with targeted therapy and sequential curative surgical procedures for initially unresectable hepatocellular carcinoma]

Objective: To report the clinical efficacy of adjuvant therapy based on pathological results following immunotherapy combined with targeted therapy and sequential curative surgical procedures in patients with initially unresectable hepatocellular carcinoma. Methods: This is a retrospective case series study. Data from 100 patients who underwent adjuvant therapy based on pathological results following immunotherapy combined with targeted therapy and sequential curative surgical procedures with long-term survival were collected from December 2018 to December 2022 at the Faculty of Hepato-Pancreato-Biliary Surgery, First Medical Center, Chinese People's Liberation Army General Hospital. According to inclusion and exclusion criteria, 47 cases were included, among which patients who met the discontinuation criteria and maintained a drug-free tumor-free status. Thirty-nine male and eight female patients were included, with an age of (54.2±18.8)years(range:38 to 73 years) at initial diagnosis. At the time of initial diagnosis, 43 cases (91.5%) were classified as Barcelona Clinic Liver Cancer(BCLC) stage C. Survival curves were made using Kaplan Meier method. Results: Forty-seven patients underwent R0 resection, all achieved a drug-free tumor-free state through postoperative adjuvant therapy based on pathological examination results. Thirty-six patients(76.6%) maintained a drug-free tumor-free survival status for more than 6 months,28 patients(59.6%) for more than 12 months,and 8 patients(17.0%) for more than 24 months. The longest drug-free tumor-free survival in this cohort reached 48 months. The median follow-up time in this study was 32 months. After diagnosis, the overall survival rates at 1- and 3- years were 97.7%(95%CI:93.4% to 100%) and 90.7%(95%CI:82.5% to 99.8%). The postoperative recurrence-free survival rates at 1- and 3- years were 91.0%(95%CI:83.0% to 99.8%) and 71.3%(95%CI:58.7% to 86.5%). Conclusions: The adjuvant therapy based on pathological results following immunotherapy combined with targeted therapy and sequential curative surgical approach provides long-term survival benefits for patients with initially unresectable hepatocellular carcinoma. Standardized adjuvant therapy maybe sustain long-term tumor-free status,and achieve drug-free tumor-free survival.

[Chronic radiation-induced rectal injury after adjuvant radiotherapy for pelvic malignant tumors: report based on a phase 3 randomized clinical trial]

Objective: Radiotherapy is one of the standard treatments for pelvic malignant tumors. However, researches associated with intestinal radiation injury and the quality of life (QoL) of patients receiving radiotherapy were lacking in the past. This study aims to analyze the occurrence of radiation-induced rectal injury after adjuvant radiotherapy for pelvic malignant tumors and call for more attention on this issne. Methods: A retrospectively observational study was conducted. Case data of cervical cancer patients from the database of STARS phase 3 randomized clinical trial (NCT00806117) in Sun Yat-sen University Cancer Center were analyzed. A total of 848 cervical cancer patients who received adjuvant radiation following hysterectomy and pelvic lymphadenectomy in Sun Yat-sen University Cancer Center from February 2008 to August 2015 were recruited. The pelvic radiation dosage was 1.8 Gy/day or 2.0 Gy/day, five times every week, and the total dosage was 40-50 Gy. Among 848 patients, 563 patients received radiation six weeks after surgery, of whom 282 received adjuvant radiation alone and 281 received concurrent chemoradiotherapy (weekly cisplatin); other 285 patients received sequential chemoradiotherapy (paclitaxel and cisplatin). Acute adverse events, chronic radiation damage of rectum, and QoL were collected and analyed. The digestive tract symptoms and QoL were evaluated based on EORTC QLQ-C30 questionnaires at one week after surgery (M0), during adjuvant therapy period (M1), and at 12 months and 24 months after the completion of treatments (M12 and M24), respectively. Higher scores in the functional catalog and overall quality of life indicated better quality of life, while higher scores in the symptom catalog indicated severe symptoms and worse QoL. Chronic radiation rectal injury was defined as digestive symptoms that were not improved within three months after radiotherapy. Grading standard of acute adverse events and chronic radiation rectal injury was according to the gastrointestinal part of National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0 (NCI-CTCAE Version 4.0). Results: The mean total radiation dosage of 848 patients was (47.8±4.6) Gy. During adjuvant therapy, the common symptoms of acute intestinal dysfunction were nausea (46.0%, 390/848), vomiting (33.8%, 287/848), constipation (16.3%, 138/848) and abdominal pain (10.3%, 87/848). At M12 and M24, the number of 0 QLQ-C30 questionnaires collected was 346 and 250, respectively. QLQ-C30 questionnaires showed that the scores of nausea or vomiting, appetite decrease, diarrhea, constipation, etc. were improved obviously at M12 or M24 compared with those at M0 or during M1 (all P<0.05). As the extension of the follow-up time, the score of the overall QoL of patients gradually increased [M0: 59.7 (0.0-100.0); M1: 63.1 (0.0-100.0); M12: 75.2 (0.0-100.0); M24: 94.1 (20.0-120.0); H=253.800, P<0.001]. Twelve months after the completion of treatments, the incidence of chronic radiation rectal injury was 9.8% (34/346), mainly presenting as abdominal pain, constipation, stool blood, diarrhea, mostly at level 1 to 2 toxicity (33/34, 97.1%). One patient (0.3%) developed frequent diarrhea (>8 times/d), which was level 3 toxicity. Twenty-four months after all treatments, the incidence of chronic radiation rectal injury was 9.6% (24/250), which was not decreased significantly compared to that in the previous period (χ(2)=0.008, P=0.927). The symotoms of one patient with level 3 toxicity was not relieved. Conclusions: The common symptoms of patients with pelvic maligant tumors during postoperative adjuvant radiotherapy include nausea, vomiting, constipation, abdominal pain and diarrhea. These symptoms are alleviated obviously at 12 and 24 months after adjuvant radiotherapy, and the QoL is significantly improved. However, a few patients may develop chronic radiation rectal injury which is not improved for years or even decades, and deserves attention in clinical practice.

[Application of deep learning neural network in pathological image classification of non-inflammatory aortic membrane degeneration]

Objective: To investigate the value of deep learning in classifying non-inflammatory aortic membrane degeneration. Methods: Eighty-nine cases of non-inflammatory aortic media degeneration diagnosed from January to June 2018 were collected at Beijing Anzhen Hospital, Capital Medical University, China and scanned into digital sections. 1 627 hematoxylin and eosin stained photomicrographs were extracted. Combined with the ResNet18-based deep convolution neural network model, 4-category classification of pathological images were performed to diagnose the non-inflammatory aortic lesion. Results: The prediction model of artificial intelligence assisted diagnosis had the best accuracy, sensitivity and precision in identifying lesions with smooth muscle cell nuclei loss, which were 99.39%, 98.36% and 98.36%, respectively. The classification accuracy of elastic fiber fragmentation and/or loss lesions was 98.08%, while that of intralamellar mucoid extracellular matrix accumulation lesions was 96.93%. The overall accuracy of the classification model was 96.32%, and the area under the curve was 0.982. Conclusions: The accuracy of deep learning neural network model in the 4-category classification of non-inflammatory aortic lesionsis confirmed based on digital photomicrographs. This method can effectively improve the diagnostic efficiency of pathologists.

Identification and characterization of differentially expressed lncRNA in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cleft palate

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous environmental pollutant and also a strong teratogen for cleft palate (CP). But up to now, the underlying molecular mechanisms of TCDD-induced CP are largely unknown. More recently, accumulating evidences are revealing important roles of long noncoding RNAs (lncRNAs) in all kinds of diseases including CP. However, the role and molecular mechanism of lncRNAs in TCDD-induced CP are still largely unexplored. Thus, identification of differentially expressed lncRNA (DEL) might help figuring out the mechanism of CP induced by TCDD. In this study, a CP offspring model of C57BL/6 female mice was generated by TCDD (64 µg/kg body weight) induce on embryo day 10 (E10). The incidence rate of CP was 100% in the TCDD group (105) after cervical dislocation on E16. Then, the high-throughput RNA sequencing (RNA-seq) was established to search a comprehensive profile of the lncRNAs. In addition, a coexpression network of lncRNA and messenger RNA (mRNA) was performed to discern potential mechanism. The result showed that 26,246 novel lncRNAs and 9635 known lncRNAs were screened out, and 413 lncRNA transcripts and 65 mRNA transcripts were identified as being significantly different between the CP group and control group. Notably, we found that there are seven lncRNAs that can target Smad1 and Smad5, which are key molecules of bone morphogenetic protein (BMP) signaling pathway, which suggested that they may be concerned with BMP signaling in TCDD-induced CP. In addition, some lncRNAs targeted the important molecules of Hippo and Wnt signaling pathways. These results suggested that characteristic lncRNA alterations may play a critical role in TCDD-induced CP, which provided a theoretical basis for further research.

[Analysis of 113 cases with mucinous cystic neoplasms in a single institutional study]

OBJECTIVE

To describe the clinicopathological characteristics and prognostic factors of mucinous cystic neoplasm(MCN).

METHODS

One hundred and thirteen patients with MCN comfirmed by histological examination admitted in People's Liberation Army General Hospital from January 1994 to June 2015 were analyzed, including 21 male and 92 female patients with mean age of (50.2±14.5) years. Forty-eight patients had incidental discovery of their cystic neoplasm for another reason, 65 patients were symptomatic, and abdominal pain or distension was main clinical symptom. Among 113 patients with MCN, 75 cases were MCN with dysplasia, and 38 cases were MCN with invasive carcinoma. Wilcoxon test and χ(2) test, et al were used to analyzed the data, respectively.

RESULTS

MCN was mostly located in body and tail of pancreas.Sex, mean age, clinical symptom, tumor size, and CA19-9 showed significant difference between MCN with dysplasia and MCN with invasive carcinoma (all P<0.05). The presence of a solid component (χ(2)=32.460, P=0.000)and main pancreatic duct dilation(χ(2)= 5.729, P=0.022) were significantly associated with malignancy. Fifty-eight patients with dysplasia were followed up, only one patient occurred tumor recurrence. Thirty-one patients with malignancy were followed up, among which there were 22 patients dead, 1-, 3-, 5-year survival of MCN with malignancy was 76.9%, 56.5%, 36.6%, respectively. Lymphatic metastasis and tumor recurrence were important prognostic factors of MCN with malignancy(both P<0.05).

CONCLUSIONS

MCN is most affected by old female with no specific symptom, most tumors are located at the body and tail of the pancreas.MCN with dysplasia have excellent prognosis underwent surgery. Even with complete resection, the long-term survival of MCN with malignancy is not satisfied.

SPAG5 upregulation predicts poor prognosis in cervical cancer patients and alters sensitivity to taxol treatment via the mTOR signaling pathway

Previously, we found that sperm-associated antigen 5 (SPAG5) was upregulated in pelvic lymph node metastasis–positive cervical cancer. The aim of this study is to examine the role of SPAG5 in the proliferation and tumorigenicity of cervical cancer and its clinical significance in tumor progression. In our study, SPAG5 expression in cervical cancer patients was detected using quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry; cervical cancer cell function with downregulated SPAG5 in vitro was explored using tetrazolium assay, flow cytometry, and colony formation and Transwell assays. SPAG5 was upregulated in tumor tissue compared with paired adjacent noncancerous tissues; SPAG5 upregulation in tumor tissues indicated poor disease-free survival, which was also an independent prognostic indicator for cervical cancer patients. In vitro study demonstrated that SPAG5 downregulation inhibited cell proliferation and growth significantly by G2/M arrest and induction of apoptosis, and hindered cell migration and invasion. Under SPAG5 downregulation, the sensitivity of cervical cancer cells differed according to taxol dose, which correlated with mammalian target of rapamycin (mTOR) signaling pathway activity. In general, SPAG5 upregulation relates to poor prognosis in cervical cancer patients, and SPAG5 is a regulator of mTOR activity during taxol treatment in cervical cancer.

Abstract P2-02-12: Computer derived image features on DCE-MRI appear to distinguish estrogen receptor-positive breast cancers with low and high oncotype DX recurrence scores

The Oncotype DX (ODX) is a 21 panel gene-expression based assay for identifying which Estrogen Receptor-positive (ER+) breast cancer (BCa) patients are candidates for adjuvant chemotherapy. The objective of this research was to identify whether computerized texture features on a staging DCE-MRI can distinguish ER+ BCa with low and high ODX recurrence scores (RS) (i.e. to distinguish which ER+ BCa patients are more likely to benefit from adjuvant hormonal therapy from those who require chemotherapy). This would provide a non-invasive, imaging based, pre-therapeutic assessment tool for predicting the appropriate treatment regimen. This work, to the best of our knowledge, is the first attempt to quantitatively correlate low versus high risk stratification via computer derived MRI measurements to corresponding risk stratification via the ODX assay.

52 ER+ BCa patient studies with high (&gt;30, N = 28) and low (&lt;18, N = 24) ODX RS were available for this study from two sites; 16 breast MRIs from the Boston Medical Center using a Phillips 1.5T magnet with a 7-channel breast coil, and 36 MRIs from the Case Medical Center using a Siemens 1.5T magnet with a 8-channel breast coil. All datasets included T1w images obtained prior to, during, and after administration of 0.1 mmol/kg of Gd-DTPA and corresponding ODX RS. For each study a radiologist picked a representative slice showing the tumor and then manually segmented the region of interest (ROI) containing the lesion. Computerized image analysis tools developed in-house via the MATLAB© programming platform were applied to the manually segmented lesion ROI for each of the 52 MRI studies to quantitatively characterize the lesion via a set of (a) 6 shape, (b) 3 pharmacokinetic (Ktrans, ve, kep) based on Tofts model (PK), (c) 12 enhancement kinetic (EK), (d) 12 intensity kinetic (IK), (e) 312 textural kinetic (TK), (f) 6 dynamic local binary pattern (DLBP), and (g) 5 dynamic histogram of oriented gradient (DHoG) features. The computer extracted features were evaluated via a linear discriminant analysis (LDA) classifier in terms of their ability to distinguish ER+ BCa as having a low or high ODX RS via a 2-fold randomized cross validation scheme. At each iteration, half of the studies were randomly selected from the 52 cases and used for training the LDA classifier and the remaining 26 studies were used for independent testing. This process was repeated 200 times. Classification performance was evaluated by area under the ROC curve (AUC). Higher AUC values suggest a stronger relationship between risk stratification via MRI attributes and ODX.

Table 1Feature classAccuracy (μ±Δ)AUC (μ±Δ)DHoG87.07%±5.66%0.89±0.04DLBP85.86%±7.82%0.83±0.07EK82.36%±8.46%0.80±0.06PK81.14%±7.55%0.78±0.07TK75.93%±6.65%0.76±0.08IK76.43%±7.23%0.75±0.12Shape71.04%±6.81%0.70±0.06

Table 1 illustrates the mean and standard deviation in accuracy and AUC values over 200 runs of randomized cross validation. DHoG, DBLP and EK features yielded the highest classification accuracy and AUC. Although lesion shape has been shown to be important for discriminating benign and malignant lesions on MRI, shape appears to be less useful in distinguishing between ER+ BCa lesions with low and high ODX RS.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-02-12.

Abstract P2-03-01: Computer extracted image texture features on T2-weighted MRI appear to correlate with nuclear morphologic descriptors from H&E-stained histopathology in estrogen receptor positive breast cancers

Oncotype DX (ODX) is a 21 panel gene-expression based assay for predicting whether patients with estrogen receptor-positive (ER+) breast cancer (BCa) are candidates for adjuvant chemotherapy. However, the time and expense associated with genomic assays suggests the need for a non-invasive, imaging-based, pre-therapeutic tool for assessment of disease risk and selection of an appropriate treatment regimen. The objective of this research was to determine whether (a) computer extracted image features on T2-weighted (T2w) MRI and H&E stained histopathology are independently able to distinguish ER+ BCa with low and high ODX recurrence scores (RS) and (b) to determine whether there is a correlation between MRI and histologic features identified as being predictive of low and high ODX risk categories.

A total of 11 ER+ BCa patients were considered in this study, based on availability of in vivo 1.5 Tesla T2w MRI. For each study, the corresponding formalin-fixed paraffin-embedded H&E stained tissue specimens were digitized at 20x (0.5 μm/pixel) using a whole-slide scanner. Of the 11 patients, 8 were identified in the low ODX (RS &lt; 18) and 3 in the high ODX (RS &gt; 30) risk categories. Each dataset was accompanied by expert annotations of (a) the lesion ROI on MRI and (b) boundaries of epithelial nuclei from a representative field-of-view on the digitized histology slide.

For each MRI study, a multi-scale, multi-orientation Gabor filter bank was convolved with the annotated lesion area providing a set of 192 texture features (FMRI). For each corresponding histology image, 471 features (FHIST) were extracted describing both nuclear morphology (NM) and Laws texture (LT) within the nuclear regions. Independent 2-sample t-tests were used to identify salient features in FMRI and FHIST that are able to distinguish low and high ODX risk categories. We found that, for the MRI dataset, Gabor texture features at several scales and orientations yielded salient features (p &lt; 0.05) while on histopathology, nuclear texture and convexity (shape) features were identified as the top discriminative features (p &lt; 0.01). Relationships between significant features were evaluated via Spearman's rank correlation test (see table), where high correlations were observed between lesion texture on T2w MRI and nuclear texture and shape on histology.

Correlation of histologic and MRI features able to distinguish low and high ODX RSHistologic feature correlated with ODXMRI feature correlated with ODXCorrelation coefficient (ρ)p-valueLT: 70 Mean HSVGF: Scale 2: Orientation 3: min/max-0.85450.0008NM: ConvexityGF: Scale 5: Orientation 6: mean-0.85450.0008LT: 70 Mean HSVGF: Scale 2: Orientation 3: min/max-0.83640.0013LT: 70 Mean HSVGF: Scale 3: Orientation 8: mean-0.83640.0013LT: 70 Mean HSVGF: Scale 3: Orientation 2: mean-0.81820.0021

Our results suggest that quantitative features extracted on both T2w MRI and histopathology can independently distinguish between low and high risk ODX classes. Moreover, some of these MRI and histologic features appear to be significantly correlated, suggesting that information regarding tumor biology is reflected in both MRI and histologic image features.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-03-01.

Abstract 3862: The potential role of CD44 in liver regeneration

Background and Aim: Liver regeneration occurs after liver damage by ischaemia, hepatitis, or in hepatocellular carcinoma (HCC) patients receiving hepatic resection or liver transplantation. Understanding the molecular bases of this process will provide novel therapeutic approaches for patients with various liver diseases. Previous studies suggested the linkage between CD44, a multifunctional cell surface receptor, and liver regeneration. The detailed role of this receptor in liver regeneration, however, remained unclear. The present study aimed at elucidating the role of CD44 in liver regeneration. Materials and Methods: A mouse model of liver regeneration induced by partial hepatectomy (PH) was employed. Serum and liver tissues were collected at different time points after PH. ELISA was performed to measure hyaluronic acid (ligand for CD44) level in serum. Flow cytometry was done to characterize liver cell populations after PH. Liver regeneration was quantified by measurement of liver mass and by immunohistochemical staining for PCNA (a proliferation marker). Quantitative PCR was performed to compare gene expression pattern of 46 genes between CD45− CD44+ cells and their CD44− counterparts. Results: Firstly, serum hyaluronic acid level was elevated at the early stage of liver regeneration. Secondly, by flow cytometry, an increase in CD45− CD44+ cell population was found. Thirdly, immunohistochemical analysis revealed active hepatocyte proliferation during this period. Interestingly, the hepatectomy-induced cell proliferation was suppressed after treating mice with anti-CD44 antibody, suggesting a functional role of CD44 in liver regeneration. Lastly, dysregulation of genes involving in cell proliferation, angiogenesis, and metabolism of hyaluronic acid was disclosed in CD45− CD44+ cells. Conclusion: The present study indicated that CD44-mediated pathways are required for liver regeneration, which may have therapeutic implications in treating liver diseases, including HCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3862. doi:1538-7445.AM2012-3862

TNF receptors differentially signal and are differentially expressed and regulated in the human heart

Tumor necrosis factor (TNF) utilizes two receptors, TNFR1 and 2, to initiate target cell responses. We assessed expression of TNF, TNFRs and downstream kinases in cardiac allografts, and compared TNF responses in heart organ cultures from wild-type ((WT)C57BL/6), TNFR1-knockout ((KO)), TNFR2(KO), TNFR1/2(KO) mice. In nonrejecting human heart TNFR1 was strongly expressed coincidentally with inactive apoptosis signal-regulating kinase-1 (ASK1) in cardiomyocytes (CM) and vascular endothelial cells (VEC). TNFR2 was expressed only in VEC. Low levels of TNF localized to microvessels. Rejecting cardiac allografts showed increased TNF in microvessels, diminished TNFR1, activation of ASK1, upregulated TNFR2 co-expressed with activated endothelial/epithelial tyrosine kinase (Etk), increased apoptosis and cell cycle entry in CM. Neither TNFR was expressed significantly by cardiac fibroblasts. In (WT)C57BL/6 myocardium, TNF activated both ASK1 and Etk, and increased both apoptosis and cell cycle entry. TNF-treated TNFR1(KO) myocardium showed little ASK1 activation and apoptosis but increased Etk activation and cell cycle entry, while TNFR2(KO) myocardium showed little Etk activation and cell cycle entry but increased ASK1 activation and apoptosis. These observations demonstrate independent regulation and differential functions of TNFRs in myocardium, consistent with TNFR1-mediated cell death and TNFR2-mediated repair.

Applications of nanotechnologies in medical practice

As medical practice enters a new era with the exciting new applications of nanoscience and technology, the paper introduces the philosophy and the principles of controlled drug delivery and the generation of tissue. It further describes and discusses new research into nanoporous materials and how encapsulation of various medical substances can create stimuli-controlled precision delivery systems. The paper goes on to highlight the process of those new materials for medical applications citing particularly a successful process for coating them onto flexible materials such as fabrics.

Cloning and characterization of a novel zinc finger protein (MDZF) that is associated with monocytic differentiation of acute promyelocytic leukemia cells

AIM

To study the characteristics of a novel zinc finger protein designated as monocytic differentiation-associated zinc finger protein (MDZF) and its role in the differentiation of leukemia cells.

METHODS

The mRNA expression of MDZF in tissues and cells was analyzed by Northern blot and RT-PCR. Polyclonal antibodies against the N terminus of MDZF were used to analyze protein expression in hematopoietic cell lines and subcellular location of MDZF in promyelocytic NB4 cells. The NB4 cells treated with TPA or ATRA at different intervals were harvested and then the expression level of MDZF protein was determined by Western blot.

RESULT

A full-length cDNA was successfully identified from a human monocyte-derived dendritic cell cDNA library which encodes 610 amino acids with eight C2H2 zinc finger motifs and one POZ domain. It was located on chromosome 3 according to the genome database. This novel zinc finger protein was designated as MDZF. One transcript isoform of MDZF was also cloned by RT-PCR. Northern blot showed that MDZF mRNA was restrictedly expressed in heart, skeleton muscle, kidney, liver, and placenta. MDZF protein was expressed in all hematopoietic cell lines examined. Immunoblotting and confocal analysis indicated a dominant cytoplasmic location of MDZF in NB4 cells. Furthermore, after NB4 cells were treated with TPA for 48 h and differentiated into monocytes, MDZF expression increased fivefold in the NB4 cells, but no effect was observed in NB4 cells treated with ATRA.

CONCLUSION

A novel zinc finger protein MDZF was cloned. MDZF is upregulated in monocytic, but not granulocytic, differentiation of NB4 acute promyelocytic leukemia cells. MDZF may be a candidate regulator of monocytic differentiation.

Cloning and Characterization of Siglec-10, a Novel Sialic Acid Binding Member of the Ig Superfamily, from Human Dendritic Cells

The Siglecs (sialic acid-binding Ig-like lectins) are a subfamily of I-type lectins, which specifically recognize sialic acids. Nine members of the family have been identified thus far. We have obtained a novel cDNA clone from a human dendritic cell cDNA library encoding a protein with sequence and structural features of the Siglec family, hence designated as Siglec-10. The full-length Siglec-10 cDNA encodes a type 1 transmembrane protein containing four extracellular immunoglobulin-like domains, a transmembrane region, and a cytoplasmic tail with two classical immunoreceptor tyrosine-based inhibitory motifs. The N-terminal V-set Ig domain has most of the amino acid residues typical of the Siglecs. Siglec-10 shows the closest homology to Siglec-5 and Siglec-3/CD33. Various cells and cell lines including monocytes and dendritic cells express Siglec-10. High levels of mRNA expression were seen in peripheral blood leukocytes, spleen, and liver. When expressed on COS-7 cells, Siglec-10 was able to bind human red blood cells and soluble sialoglycoconjugates in a sialic acid-dependent manner. The identification of Siglec-10 as a new Siglec family member and its expression profile, together with its sialic acid-dependent binding capacity, suggest that it may be involved in cell-cell recognition by interacting with sialylated ligands expressed on specific cell populations.

Identification and characterization of DPZF, a novel human BTB/POZ zinc finger protein sharing homology to BCL-6

The C2H2 zinc finger protein family is one of the largest families of transcription factors. We identified a novel BTB/POZ zinc finger gene from human dendritic cells (DC), which encodes a 733-residue protein with a BTB/POZ domain at the N-terminal and 4 C2H2 zinc fingers at C-terminal. It was designated dendritic cell-derived BTB/POZ zinc finger (DPZF). DPZF protein shares closest homology to BCL-6, with the highest homology present in the BTB/POZ and zinc finger domains. Like BCL-6, DPZF gene is localized on chromosome 3. It is widely expressed in hematopoietic tissues, including DC, monocytes, B cells, and T cells. DPZF protein expression is detectable in lymphoid neoplasm with a molecular mass of 100 kD, especially in B lymphoma. These indicate that DPZF may be a transcription factor closely related to BCL-6, and may be involved in hematopoiesis, oncogenesis, and immune responses.

Identification of a novel type I cytokine receptor CRL2 preferentially expressed by human dendritic cells and activated monocytes

From a human dendritic cell (DC) cDNA library, we identified a novel type I cytokine receptor, designated as cytokine receptor-like molecule 2 (CRL2). CRL2 cDNA encoded a 371-residue type I transmembrane protein with an extracellular domain of 210 residues and an intracellular domain of 119 residues. Its extracellular domain contains conserved cysteine residues and WAS-like motif in place of the hallmark of WSXWS motif present in other type I cytokine receptors. The intracellular domain contained a membrane-proximal "box 1" motif and conserved tyrosine residue potentially as a binding site for signal transducing molecules. CRL2 protein shares significant homology with common cytokine receptor (gammac) and interleukin-13 receptor alpha1 chain. Northern blot analysis showed that CRL2 was restrictedly expressed by spleen and peripheral blood leukocytes, and abundantly expressed by HL-60 cells. RT-PCR analysis demonstrated that CRL2 was preferentially expressed by DC and monocytes. Interestingly, CRL2 expression was up-regulated when monocytes were activated by LPS. These indicate that CRL2 may be involved in the biological functions of DC and monocytes. The Ba/F3 transfectants of CRL2 was retrovirally established with the expressed FLAG-tagged CRL2 in the size of approximately 48 kD, which could be efficiently immunoprecipitated. We also prepared a CRL2Ig fusion protein. The identification of its ligand and involvement of signal transduction will help to elucidate its potential function.

Genetic approach to insight into the immunobiology of human dendritic cells and identification of CD84-H1, a novel CD84 homologue

To better understand the immunobiology of dendritic cells (DCs), we took the expressed sequence tag (EST) approach to describe their transcript profile and discovered novel genes. ESTs (n = 25,668) were generated from monocyte-derived DCs, and 15,863 ESTs (61.8%) represented unique genes in GenBank. Integration of ESTs allowed for the generation of a profile of 4,367 known genes and identification of > 100 novel genes. HLA-DR invariant chain p33, cathepsin D, HLA-DR alpha chain, beta2-microglobulin, HLA-DP beta chain, CD11a, and mannose receptor were in the top 30 transcripts, and 451 known genes were potentially associated with the immunobiology of DCs. This transcript profile was consistent with the unique antigen-presenting capacity of DCs and provided invaluable information to better understand the immunobiology of DCs. On the basis of the EST database, a full-length novel gene was identified that exhibited close homology with CD84; it was designated CD84-H1. The full-length cDNA of CD84-H1 contained an open reading frame of 870 bp encoding a type I transmembrane protein of 289 amino acids. Consistent with the structural feature of the CD2 family, the predicted 270-amino acid mature protein of CD84-H1 contained two extracellular immunoglobulin-like domains that shared homology with CD2 family members, e.g., CD84, Ly-9, CD48, and signaling lymphocyte activation molecule. Its intracellular domain was short and contained no putative signaling structure. Northern blot analysis revealed that CD84-H1 expression was predominantly restricted in hematopoietic tissues. Reverse transcription-PCR analysis showed that it was widely expressed in the immune cells, including monocytes, DCs, B cells, and T cells. These data indicate that CD84-H1 may be relevant to immune responses.

Therapy-related myelodysplastic syndrome after eradication of acute promyelocytic leukemia: cytogenetic and molecular features

The use of all trans-retinoic acid and combination chemotherapy has made acute promyelocytic leukemia (APL) a potentially curable leukemia. Late sequelae of the treatment of APL have therefore become an important consideration in the overall treatment strategy. We report a patient with APL who achieved complete clinical and molecular remission after treatment with the topoisomerase II inhibitors daunorubicin, mitoxantrone, etoposide, and the anti-metabolite cytosine arabinoside. Seven years later, she developed therapy-related myelodysplastic syndrome (t-MDS) without any evidence of relapse of the APL clone. Karyotypic and molecular cytogenetic analysis showed complex cytogenetic aberrations, including deletion of the long arm of chromosome 5, monosomy 7, but without rearrangement of the MLL gene/11q23. Interestingly, this case would be classified clinically as "epipodophyllotoxin related MDS," but pathologically as "alkylating-agent related MDS" according to the recently proposed World Health Organization (WHO) classification system for MDS. This case of t-MDS in an APL patient in durable remission highlights the importance of avoiding long-term treatment related toxicities, as APL is a potentially curable leukemia.

Molecular cloning and characterization of a novel CXC chemokine macrophage inflammatory protein-2 gamma chemoattractant for human neutrophils and dendritic cells

Chemokines play important roles in leukocyte trafficking as well as function regulation. In this study, we described the identification and characterization of a novel CXC chemokine from a human dendritic cell (DC) cDNA library, the full-length cDNA of which contains an open reading frame encoding 111 aa with a putative signal peptide of 34 aa. This CXC chemokine shares greatest homology with macrophage inflammatory protein (MIP)-2alphabeta, hence is designated as MIP-2gamma. Mouse MIP-2gamma was identified by electrocloning and is highly homologous to human MIP-2gamma. Northern blotting revealed that MIP-2gamma was constitutively and widely expressed in most normal tissues with the greatest expression in kidney, but undetectable in most tumor cell lines except THP-1 cells. In situ hybridization analysis demonstrated that MIP-2gamma was mainly expressed by the epithelium of tubules in the kidney and hepatocytes in the liver. Although no detectable expression was observed in freshly isolated or PMA-treated monocytes, RT-PCR analysis revealed MIP-2gamma expression by monocyte-derived DC. Recombinant MIP-2gamma from 293 cells is about 9.5 kDa in size and specifically detectable by its polyclonal Ab developed by the immunization with its 6His-tagged fusion protein. The eukaryotically expressed MIP-2gamma is a potent chemoattractant for neutrophils, and weaker for DC, but inactive to monocytes, NK cells, and T and B lymphocytes. Receptor binding assays showed that MIP-2gamma does not bind to CXCR2. This implies that DC might contribute to the innate immunity through the production of neutrophil-attracting chemokines and extends the knowledge about the regulation of DC migration.

Cloning of DPK, a novel dendritic cell-derived protein kinase activating the ERK1/ERK2 and JNK/SAPK pathways

Mitogen-activated protein kinase (MAPK) cascades are the major signaling systems transducing extracellular signals into intracellular responses, which mainly include the extracellular signal-regulated kinase (ERK) pathway, the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) pathway, and the p38 pathway. From dendritic cell cDNA library, we isolated a full-length cDNA encoding a potentially novel 898-residue kinase, which was designated DPK. The protein contained a potential kinase domain at the N-terminal exhibiting homology with MEKK1-, MEKK2-, MEKK3-, MEKK4-, MEKK5-, Tpl-2-, and p21-activated kinases (PAKs), but no GTPase-binding domain which is characteristic of PAKs. Northern blotting analysis showed that DPK was ubiquitously expressed in normal tissues, with abundant expression in kidney, skeletal muscle, heart, and liver. When overexpressed in transfected NIH3T3 cells, it could activate both the ERK1/ERK2 pathway and the SAPK pathway in a dose-dependent manner, but not affect the p38 pathway. These findings suggested that DPK might be a novel candidate MAPKKK.

Neutrophil functions of Chinese neonates

OBJECTIVE

To delineate neutrophil function of preterm and full-term neonates of Chinese origin.

METHODS

Chinese neonates admitted to two major Hong Kong neonatal units were randomly selected for the study. Candidacidal activity, phagocytosis, chemotaxis and nitroblue tetrazolium reduction scores were evaluated from blood.

RESULTS

Except for chemotactic activity, the neutrophil functions of Chinese preterm neonates were similar to Chinese full-term neonates. The candidacidal activity of males was significantly lower when compared with female neonates. Compared with adult controls, both term and preterm infants had similar phagocytic activities although their candidacidal activities and chemotactic index were significantly decreased. Neutrophil function of Chinese infants was nearer to that of adult controls than historically reported for western infants.

CONCLUSION

: Preterm Chinese neonates had similar neutrophil function to full-term infants. Neutrophil function of Chinese infants was more mature than that of western infants.

Crystal structure of the anti-(carcinoembryonic antigen) single-chain Fv antibody MFE-23 and a model for antigen binding based on intermolecular contacts

MFE-23 is the first single-chain Fv antibody molecule to be used in patients and is used to target colorectal cancer through its high affinity for carcinoembryonic antigen (CEA), a cell-surface member of the immunoglobulin superfamily. MFE-23 contains an N-terminal variable heavy-chain domain joined by a (Gly(4)Ser)(3) linker to a variable light-chain (V(L)) domain (kappa chain) with an 11-residue C-terminal Myc-tag. Its crystal structure was determined at 2.4 A resolution by molecular replacement with an R(cryst) of 19.0%. Five of the six antigen-binding loops, L1, L2, L3, H1 and H2, conformed to known canonical structures. The sixth loop, H3, displayed a unique structure, with a beta-hairpin loop and a bifurcated apex characterized by a buried Thr residue. In the crystal lattice, two MFE-23 molecules were associated back-to-back in a manner not seen before. The antigen-binding site displayed a large acidic region located mainly within the H2 loop and a large hydrophobic region within the H3 loop. Even though this structure is unliganded within the crystal, there is an unusually large region of contact between the H1, H2 and H3 loops and the beta-sheet of the V(L) domain of an adjacent molecule (strands DEBA) as a result of intermolecular packing. These interactions exhibited remarkably high surface and electrostatic complementarity. Of seven MFE-23 residues predicted to make contact with antigen, five participated in these lattice contacts, and this model for antigen binding is consistent with previously reported site-specific mutagenesis of MFE-23 and its effect on CEA binding.

Evidence that cysteine-166 is the active-site nucleophile of Pseudomonas aeruginosa amidase: crystallization and preliminary X-ray diffraction analysis of the enzyme

Wild-type and site-specific mutants C166S and C166A (Cys-166-->Ser and Cys-166-->Ala respectively) of the amidase (acylamide amidohydrolase, EC 3.5.1.4) from Pseudomonas aeruginosa were expressed in Escherichia coli by using the vector pKK223-3. Both mutant proteins were catalytically inactive but showed complete cross-reactivity with polyclonal antiserum raised against the wild-type enzyme, as well as CD spectra identical with that of the wild-type enzyme, which were indicative of correct folding. Cys-166 is therefore implicated as the active-site nucleophile. Titration of free thiol groups with 5,5'-dithiobis-(2-nitrobenzoic acid) indicated that Cys-166 is not a rapidly reacting residue. Crystals of both wild-type and C166S amidase grew with identical, rhombohedral morphology; X-ray diffraction analysis established the unit cell dimensions (a=b=c=84 A; alpha=beta=gamma=75 degrees) and space group (R3 or R32). These results imply a quaternary structure of six subunits, with most probably 32 symmetry; the existence of a hexameric structure was supported by molecular mass determinations based on gel filtration and electrophoretic mobility.

Enhanced antitumor immune responses of IL-2 gene-modified tumor vaccine by combination with IL-1 and low dose cyclophosphamide

To enhance the antitumor immunity induced by IL-2 gene-modified tumor vaccine, we proposed a combined protocol to treat tumor-bearing mice using IL-2 gene-modified tumor vaccine in combination with IL-1 and low-dose Cyclophosphamide(Cy). After treatment with IL-2 gene-modified B16 melanoma cell vaccine alone, the pulmonary metastases of tumor-bearing mice were reduced and their survival time was prolonged. The anti-metastases effect was improved when the vaccine was used in combination with IL-1 or low-dose Cy. The best therapeutic effect was achieved when the IL-2 gene-modified vaccine was combined with IL-1 and low-dose Cy. The cytotoxicity of the splenic CTL, NK, and the levels of IL-2, TNF secreted by splenocytes increased after tumor-bearing mice were treated with the IL-2 gene-modified tumor vaccine. The above antitumor immune functions were augmented more significantly when IL-1, low-dose Cy were used in combination with IL-2 genemodified tumor vaccine. These results demonstrated that the IL-2 gene modified vaccine could exert more potent anti-metastases effects when it is combined with IL-1 or/and low-dose Cy by activating the specific and non-specific antitumor immune responses more effectively.

Inhibition of endometrial cancer cell lines by mifepristone (RU 486)

OBJECTIVE

To determine the role of mifepristone (RU 486) in the growth of endometrial cancer cell lines, and the mechanism associated with this regulation.

METHODS

Three endometrial cancer cell lines (Hec-1A, KLE, and RL95-2) were used in this study. Growth inhibition was demonstrated by sulforhodamine B cytotoxicity assay. Mode of inhibition by RU 486 was studied by induction of DNA fragmentation. The effect of RU 486 on steady-state accumulation of the progesterone and glucocorticoid receptors (PRs and GRs, respectively) and apoptosis-associated gene products was studied by Western blotting.

RESULTS

We demonstrated a dose-dependent inhibition of growth in all of the three endometrial cancer cell lines. Following treatment with 5.0 micrograms/mL of RU 486, there was 39.3%, 66.3%, and 75.5% inhibition of KLE, Hec-1A, and RL95-2 cells, respectively. Decreased expression of GR in RL95-2 (0.1-10 micrograms/mL) and in KLE cells (10 micrograms/mL) was observed. A marked decrease of PR was seen with RL95-2 cells at 10 micrograms/mL, there was no change in the KLE cells, and a dose-dependent decrease was seen with Hec-1A cells. Various levels of apoptosis were demonstrated by DNA fragmentation in all three cell lines. Of the genes associated with apoptosis, dose-dependent reduction of bax expression was demonstrated in KLE cells, while induction of WAF-1 was seen in Hec-1A and RL95-2 cells, and reduction of bcl-2 was demonstrated in RL95-2 cells.

CONCLUSION

Clinically achievable doses of RU 486 inhibit endometrial cancer cell lines. The mechanism of inhibition involves apoptosis, and regulation of bax, bcl-2, and WAF-1 is demonstrated. Therapeutic application of these findings remains to be determined.

Crystal structure of the zinc-dependent beta-lactamase from Bacillus cereus at 1.9 A resolution: binuclear active site with features of a mononuclear enzyme

The structure of the zinc-dependent beta-lactamase II from Bacillus cereus has been determined at 1.9 A resolution in a crystal form with two molecules in the asymmetric unit and 400 waters (space group P3121; Rcryst = 20.8%). The active site contains two zinc ions: Zn1 is tightly coordinated by His86, His88, and His149, while Zn2 is loosely coordinated by Asp90, Cys168, and His210. A water molecule (W1) lies between the two zinc ions but is significantly closer to Zn1 and at a distance of only 1.9 A is effectively a hydroxide moiety and a potential, preactivated nucleophile. In fact, Asp90 bridges W1 to Zn2, and its location is thus distinct from that of the bridging water molecules in the binuclear zinc peptidases or other binuclear zinc hydrolases. Modeling of penicillin, cephalosporin, and carbapenem binding shows that all are readily accommodated within the shallow active site cleft of the enzyme, and the Zn1-bound hydroxide is ideally located for nucleophilic attack at the beta-lactam carbonyl. This enzyme also functions with only one zinc ion present. The Zn1-Zn2 distances differ in the two independent molecules in the crystal (3.9 and 4.4 A), yet the Zn1-W1 distances are both 1.9 A, arguing against involvement of Zn2 in W1 activation. The role of Zn2 is unclear, but the B. cereus enzyme may be an evolutionary intermediate between the mono- and bizinc metallo-beta-lactamases. The broad specificity of this enzyme, together with the increasing prevalence of zinc-dependent metallo-beta-lactamases, poses a real clinical threat, and this structure provides a basis for understanding its mechanism and designing inhibitors.

Adenovirus-mediated GM-CSF gene and cytosine deaminase gene transfer followed by 5-fluorocytosine administration elicit more potent antitumor response in tumor-bearing mice

Antitumor effects of combined transfer of suicide and cytokine genes were investigated in this study. Adenovirus harboring E. coli cytosine deaminase gene (AdCD) and adenovirus harboring murine granulocyte-macrophage colony-stimulating factor gene (AdGMCSF) were used simultaneously for in vivo gene transfer in melanoma-bearing mice. Growth inhibition of established tumors and prolongation of survival period were observed more significantly in tumor-bearing mice after transfection with AdGMCSF and AdCD followed by continuous injection of prodrug 5-fluorocytosine (5FC) when compared with mice treated with control adenovirus AdlacZ/5FC, AdCD/5FC or AdGMCSF alone (P < 0.01). After combined therapy the expression of MHC-I (H-2Db) and B7-1 molecules on freshly isolated tumor cells increased greatly and more dendritic cells and CD8+ T cells infiltrated into the tumor mass. The activity of specific cytotoxic T lymphocytes was also found to be induced more significantly after the combined therapy. Further experiments showed that apoptosis of tumor cells and induction of antitumor immune response might be involved in the mechanisms of the tumor cell killing by the combined therapy. Our results demonstrated that combined transfer of the GM-CSF and CD suicide genes, being able to inhibit the growth of melanoma synergistically and induce specific antitumor immune response efficiently, thus addressing the drawbacks of suicide gene therapy or cytokine gene therapy which were proved to be not satisfactory when used alone, might be of therapeutic potential for gene therapy of cancer.

Umbilical cord blood interleukin-6 levels and neonatal morbidity

OBJECTIVE

To study umbilical cord interleukin-6 levels and the occurrence of neonatal sepsis, congenital pneumonia, necrotizing enterocolitis, and grade II-IV intraventricular hemorrhage.

METHODS

Umbilical cord blood was collected from 133 preterm newborns. The study population was divided according to the presence or absence of neonatal complications. Interleukin-6 levels and clinical characteristics were compared by univariate and multivariate analyses.

RESULTS

Sixteen neonates had adverse outcomes, and 117 were unaffected. The median interleukin-6 level was significantly higher in affected than in unaffected infants (145 pg/mL versus 0 pg/mL, P = .002). Elevated interleukin-6 levels were associated independently with neonatal morbidity in multiple logistic regression modeling that included gestational age, birth weight, and antenatal steroid exposure.

CONCLUSION

Umbilical cord blood interleukin-6 levels are elevated in neonates who subsequently develop sepsis, congenital pneumonia, necrotizing enterocolitis, or grade II-IV intraventricular hemorrhage.

In vivo gene therapy of murine melanoma mediated by recombinant vaccinia virus encoding human IL-2 gene

Direct gene transfer into somatic tissue iii vivo is a developing technology with potential application for cancer gene therapy. In this study, recombinant vaccinia virus encoding human IL-2 gene (rVV-IL-2) was used as a candidate vector in mediating iii vivo gene therapy. After rVV-IL-2 was expanded in VERO cells for 72 h, high titer (10(8)-10(10) PFU/ml) rVV-IL-2 were harvested. When 10(6) murine melanoma cells (F16-F10) were infected with rVV-IL-2, about 200 U/ml IL-2 activity was detected in the supernatants at 8 h, and the up-regulation of ICAM-1 and MHC-I expressions on the melanoma cells were observed. The treatment of murine melanoma model by local injection of rVV-IL-2 into the tumor site showed that rVV-IL-2 transfection significantly inhibited the tumor growth and prolonged the survival time of tumor-bearing mice. The splenocytes from rVV-IL-2 treated mice showed higher cytotoxicities of NK, LAK and CTL in comparison with those from the controls. These results suggest that in vivo transfection mediated by rVV-IL-2 has potential effectiveness in enhancing host immunity and would be a useful approach to cancer gene therapy.

Apoptosis as a measure of chemosensitivity to cisplatin and taxol therapy in ovarian cancer cell lines

OBJECTIVE

Cisplatin- and Taxol-induced apoptosis was studied in four human ovarian cancer cell lines to evaluate apoptosis as a measure of chemosensitivity.

METHODS

In vitro sensitivities of OVCAR-3, SKOV-3, UL-1, and UL-2 cells to cisplatin or Taxol were determined by the sulforhodamine B assay. Induction of apoptosis was studied by DNA fragmentation following treatment with cisplatin and/or Taxol after 24- and 48-hr exposure. DNA fragmentation was further quantitated by the diphenylamine assay and the proportion of cells in the G1, G2/M, and S phase of the cell cycle was determined by flow cytometry. Presence of the p53 gene product was examined by Western blotting.

RESULTS

The four cell lines represent various sensitivities to cisplatin and Taxol (LD50 range for cisplatin, 5-30 microg/ml; Taxol, 30-1000 nM). UL-2 represents a resistant cell line which was 10-30 times resistant to Taxol and 6 times resistant to cisplatin when compared to the others. Demonstration of apoptosis correlated with the sensitivity of the cell lines to both cisplatin and Taxol for OVCAR-3 and UL-2. DNA fragmentation of OVCAR-3 was uniformly present when treated with cisplatin or Taxol, at 24 or 48 hr. UL-2 demonstrated no apoptosis after 24 or 48 hr of treatment with either cisplatin or Taxol. When sequencing experiments were performed with cisplatin and Taxol, DNA fragmentation correlated with the cytotoxicity assays, except in UL-1 cells where no significant difference was observed in different interactions of cisplatin and Taxol. Pretreatment with Taxol generally resulted in enhanced cytotoxicity in a schedule-dependent manner, and increased fragmentation was demonstrated; cisplatin pretreatment consistently resulted in decreased fragmentation. Quantitation of the fragmented DNA correlated with that seen on gel electrophoresis. OVCAR-3 and UL-1 demonstrated the greatest change from baseline at 24 hr (3.8 and 3.7 times baseline, respectively), whereas UL-2 had little change from the baseline following treatment. G1 arrest occurred more readily in OVCAR-3 and SKOV-3 cells. UL-2 cells had very little change in the proportion of cells entering G1 arrest, but had a significant increase in the G2/M proportion. In OVCAR-3, UL-1, and UL-2 cells, we demonstrated the presence of an aberrantly expressed p53 gene product, while no p53 was detected in the SKOV-3 cells.

CONCLUSIONS

Our findings indicate that the ability to achieve significant cytotoxicity by cisplatin and Taxol may be directly related to the induction of apoptosis; however, cellular and genetic characteristics determine the eventual outcome of these treatments.

Crystallization of a complex between the Fab fragment of a human immunoglobulin M (IgM) rheumatoid factor (RF-AN) and the Fc fragment of human IgG4

Rheumatoid factors (RF) are the characteristic autoantibodies found in patients with rheumatoid arthritis. They recognize epitopes in the Fc region of immunoglobulin G (IgG) and are often of the IgM isotype. In order to analyse the nature of RF-Fc interactions, we have crystallized a complex between the Fab fragment of a human monoclonal IgM rheumatoid factor (RF-AN) and the Fc fragment of human IgG4. The stoichiometry of the complex within the crystals was found to be 2:1 Fab:Fc. The crystals diffracted X-rays to 0.3 nm resolution, and the space group was C2, with cell dimensions a = 16.03 nm, b = 8.19 nm, c = 6.42 nm, beta = 98.3 degrees. We have also determined the sequence of the variable region of the RF-AN light chain, not hitherto reported. This belongs to the V lambda III-a subgroup and is closely related to the germline gene Humlv318, from which it differs in three amino acid residues. This is the first reported crystallized complex between a human autoantibody and its autoantigen.

Crystallization and X-ray analysis of a single fab binding domain from protein L of Peptostreptococcus magnus

Protein L is a multidomain cell wall constituent of certain strains of Peptostreptococcus magnus which binds to the variable domain of immunoglobulin kappa-light chains. A single immunoglobulin-binding domain of M(r) = 9000 from this protein has been isolated and crystallized. The crystals are of space group P4(2)2(1)2, with cell dimensions a = b = 66.9 A, c = 68.3 A, and diffract to at least 2.2 A resolution. The asymmetric unit of the crystal contains two molecules of the protein L domain, related by a noncrystallographic 2-fold axis, as revealed by a self-rotation function calculated with native diffraction data.