Spontaneous remission in diffuse large cell lymphoma: a case report.

BACKGROUND: Spontaneous remission in solid malignancies has been documented. However, spontaneous remission in aggressive diffuse large b cell lymphoma is exceedingly rare. Previous reports of lymphoma remission suggest that not yet fully characterized tumor-intrinsic and microenvironment mechanisms cooperate with spontaneous regression. CASE DESCRIPTION: Here, we report the case of an 88-year-old white woman with diffuse large b cell lymphoma (follicular lymphoma transformed) who achieved morphologic spontaneous remission 3 months after her diagnostic core biopsy. We examined 16 similar cases of diffuse large b cell lymphoma suggesting that spontaneous remission is preferentially observed in elderly patients soon after their biopsy microtrauma, especially if malignancies are Epstein-Barr virus driven and activated B-cell type. CONCLUSION: Our case and reported analysis highlight that anti-tumor adaptive T cell responses are potentially augmented in a subset of patients leading to lymphoma regression. In these patients, it is possible that "primed" innate anti-tumor T cell immunity is enhanced in immunogenic lymphoma subtypes after tissue biopsy. Our case and analysis not only reinforce the role of innate T cell anticancer immunity, but also originates potential proof of concept for investigation of unexplored pathways that could favorably impact T cell therapy.

Distinguishing direct binding interactions from allosteric effects in the protease-HK97 prohead I δ domain complex by amide H/D exchange mass spectrometry.

A major question in mapping protein-ligand or protein-protein interactions in solution is to distinguish direct-binding interactions from long-range conformational changes at allosteric sites. We describe here the applicability of amide hydrogen deuterium exchange mass spectrometry (HDXMS) in addressing this important question using the bacteriophage HK97 capsid proteins' interactions with their processing protease. HK97 is a lambda-like dsDNA bacteriophage that is ideal for studies of particle assembly and maturation. Its capsid precursor protein is composed of two main regions, the scaffolding protein (δ-domain, residues 2-103), and the coat subunit (residues 104-385), which spontaneously forms a mixture of hexamers and pentamers upon association. Activation of the viral protease, which occurs after particle assembly, is initiated by the protease mediated digestion of the scaffolding domains to yield Prohead-2. This irreversible step is obligatory for activation of the virus maturation pathway. Here we provide an "addendum" to our previous study of Prohead I and Prohead I+pro (a transient complex of Prohead I and the protease) where we investigated the interactions between the δ domain and the packaged protease using HDXMS. Our results revealed two sites on the δ domain: one set of contiguous peptides that showed decreased exchange at the protease binding site at early time points of deuterium labeling and another separate set of continuous peptides that showed decreased exchange at later time points. Even though this cannot reveal the time scales of molecular processes governing binding and allostery, we believe this differential pattern of exchange across deuteration times can allow spatial distinction between binding sites and long range conformational changes with allosteric implications. This partitioning can be discerned from the lag between noncontiguous regions on a protein showing maximal changes in deuterium exchange and highlights a powerful application of HDXMS in distinguishing direct binding in transient protein-protein interactions from allosteric changes.

Probing the biophysical interplay between a viral genome and its capsid.

The interaction between a viral capsid and its genome governs crucial steps in the life cycle of a virus, such as assembly and genome uncoating. Tuning cargo-capsid interactions is also essential for successful design and cargo delivery in engineered viral systems. Here we investigate the interplay between cargo and capsid for the picorna-like Triatoma virus using a combined native mass spectrometry and atomic force microscopy approach. We propose a topology and assembly model in which heterotrimeric pentons that consist of five copies of structural proteins VP1, VP2 and VP3 are the free principal units of assembly. The interpenton contacts are established primarily by VP2. The dual role of the genome is first to stabilize the densely packed virion and, second, on an increase in pH to trigger uncoating by relaxing the stabilizing interactions with the capsid. Uncoating occurs through a labile intermediate state of the virion that reversibly disassembles into pentons with the concomitant release of protein VP4.

Probing the impact of loading rate on the mechanical properties of viral nanoparticles.

The effects of changes in the loading rate during the forced dissociation of single bonds have been studied for a wide variety of interactions. Less is known on the loading rate dependent behaviour of more complex systems that consist of multiple bonds. Here we focus on viral nanoparticles, in particular the protein shell (capsid) that protects the viral genome. As model systems we use the well-studied capsids of the plant virus Cowpea Chlorotic Mottle Virus (CCMV) and of the bacteriophages φ29 and HK97. By applying an atomic force microscopy (AFM) nanoindentation approach we study the loading rate dependency of their mechanical properties. Our AFM results show very diverse behaviour for the different systems. In particular, we find that not only the breaking force, but also the spring constant of some capsids depend on the loading rate. We describe and compare the measured data with simulation results from the literature. The unexpected complex loading rate dependencies that we report present a challenge for the current theoretical considerations aimed at understanding the molecular level interactions of highly ordered protein assemblies.

Immune response capacity after human splenic autotransplantation: restoration of response to individual pneumococcal vaccine subtypes.

OBJECTIVE: To evaluate features of general immune function, in particular the restoration of the humoral immune response to pneumococcal capsular polysaccharides, in humans undergoing a spleen autotransplantation after splenectomy because of trauma. SUMMARY BACKGROUND DATA: After splenectomy, patients have an increased risk of overwhelming infection or sepsis involving encapsulated bacteria such as pneumococci. The value of human spleen autotransplantation after splenectomy because of trauma has long been questioned. Mononuclear phagocyte system function appeared to be similar to that in splenectomized persons. The presence of specific antipneumococcal antibodies would allow other parts of the mononuclear phagocyte system, such as those in the liver, to phagocytose opsonized bacteria. METHODS: Ten consecutive patients undergoing splenectomy followed by autotransplantation were compared with the next 14 consecutive patients undergoing splenectomy alone. After a minimum of 6 months, the patients were vaccinated with 23-valent pneumococcal vaccine. Blood samples were taken at the time of vaccination and after 3 and 6 weeks for antipneumococcal capsular polysaccharides IgM and IgG enzyme-linked immunosorbent assay against types 3, 4, 6, 9, 14, and 23. Splenic regrowth was evaluated by scintigraphy. RESULTS: Surprisingly, several of the nonautotransplanted patients showed scintigraphic activity, indicating the presence of either accessory spleens or traumatic seeding (splenosis). Significant antibody titer increases (more than twofold) were found for both IgM and IgG in the autotransplanted patients. Splenectomized-only patients showed no significant increase in Ig levels in patients without splenic regrowth and partial improvement in patients with splenosis/accessory spleens. CONCLUSIONS: Considering this significant antipneumococcal antibody increase, spleen autotransplants can be expected to permit an adequate humoral response to pneumococcal infections and presumably also to other TI-2 antigens, and to protect against overwhelming postsplenectomy infection or sepsis.

Inexpensive 4-hour micro-agar dilution susceptibility determination method.

Using a micro-agar dilution (MAD) method in which microscope slides are covered with a thin film of agar, and MICs are read microscopically after a 4-h incubation, 18 antibiotics were tested against 29 to 32 microorganisms each. Identical MICs were obtained for microscopic MAD MICs performed in duplicate in 87.1% of the antibiotic-microorganism combinations, and 97.9% were identical within one dilution. When read macroscopically after an 18-h incubation, identical duplicate MICs were obtained in 86.8% of the cases, and 98.4% were identical within one dilution. Using agar dilution as the "gold standard," the correlation obtained with MAD slides read microscopically at 4 h was 94.3%, and macroscopic correlation at 18 h was 97.6%. The correlation of MAD slides with agar dilution for the groups of microorganisms most frequently used was as follows (microscopic/macroscopic): Staphylococcus aureus 96%/98%; Streptococcaceae 97%/98%; Enterobacteriaceae 98%/99%; and Pseudomonadaceae 95%/98%. At the present rate of exchange (fl 1.60 = $1.00f1p4he cost of a MAD slide, including labor, is $1.28 (20 microorganisms tested) or $0.06 per microorganism-antibiotic combination tested. This method is easy to perform, rapid, and inexpensive. It is suitable for use in routine and research laboratories.

Use of PCR with feces for detection of Helicobacter pylori infections in patients.

PCR was performed for the detection of Helicobacter pylori in feces from 24 patients with proven infections. Several precautions were taken to overcome possible inhibition of PCR with feces. In the first 12 patients, feces were examined shortly after endoscopy. In another group of 12 patients, who were treated during 2 weeks with omeprazole (40 mg each day) to increase gastric pH, feces were examined as well. H. pylori target DNA could not be detected in the stools of any of the 24 infected patients. It was concluded that there was no substantial shedding of H. pylori in feces from either group of patients.

In vitro studies on stability and development of metronidazole resistance in Helicobacter pylori.

Seventy isolates of Helicobacter pylori from antral biopsy samples were tested for their susceptibilities to metronidazole by agar dilution. Seven (10%) of these clinical isolates appeared to be resistant to metronidazole. Sixty-three strains were susceptible. In 42 (67%) of the 63 susceptible isolates, resistant isolates were obtained by serial passage on plates containing subinhibitory concentrations of metronidazole. In 10 of these 42 strains, the acquired resistance appeared to be unstable. The difference between the stability of resistance that occurred after one or two passages and the stability of resistance that occurred after three passages was statistically significant (P < 0.006). Primary resistance in clinical isolates was a stable phenomenon. Whether the resistance that emerges during therapy in patients is stable or unstable needs to be established.

Demonstration of circulating pneumococcal immunoglobulin G immune complexes in patients with community-acquired pneumonia by means of an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay was developed for quantitation of circulating immune complexes (CICs) containing specific antipneumococcal immunoglobulin G (IgG). These CICs were detected in 17 (85%) of 20 patients with bacteremic pneumococcal pneumonia, 4 (36.4%) of 11 patients with probable pneumococcal pneumonia, 3 (16.7%) of 18 patients with pneumonia of other (nonpneumococcal) etiology, and 13 (41.9%) of 31 patients with pneumonia of unknown etiology. There was no correlation between CICs and serum IgG antibody levels. Pneumococcal capsular antigen was demonstrated in dissociated CICs by latex agglutination.

Sensitivity of culture compared with that of polymerase chain reaction for detection of Helicobacter pylori from antral biopsy samples.

Polymerase chain reaction (PCR) was used to test the sensitivity of standard bacteriological culture of Helicobacter pylori. The tests were concordant in 97% of cases. PCR did not detect more treatment failures after triple treatment than did the standard culture method. In the present study, culture was as sensitive as PCR for the detection of H. pylori.

Antigen detection in oropharyngeal secretions for rapid diagnosis of pneumococcal pneumonia.

To determine the value of detection of antigen in the oropharynx in the diagnosis of pneumococcal pneumonia, oropharyngeal secretions were cultured for the presence of Streptococcus pneumoniae and tested for the presence of pneumococcal antigen. Sputum (if available) collected on the same day was also investigated for the presence of antigen. Detection of pneumococcal antigen was found to be directly related to the severity of pneumococcal carriership or infection (p < 0.0001) and was not related to culture results. Patients with pneumococcal pneumonia had the highest antigen detection rate (38%), followed by patients with pneumonia of unknown etiology (32%) and patients with an acute lower respiratory tract infection due to Streptococcus pneumoniae (20%). Pneumococcal carriers had a detection rate of only 9%. Antigen could be detected in only one patient of the control groups. Although antigen detection in sputum was superior to that in oropharyngeal secretions, concordant results were obtained in 8 (40%) and 6 (36%) patients with pneumococcal pneumonia and pneumonia of unknown etiology respectively. The results strongly suggest that pneumococcal carriage seldom leads to a detectable level of antigen, and that antigen detection in the oropharynx appears to be of additive value in the diagnosis of pneumococcal pneumonia.

Rapid detection of pneumococcal antigen in pleural fluid of patients with community acquired pneumonia.

BACKGROUND: Detection of pneumococcal antigen may help to increase the rate of diagnosis of pneumococcal pneumonia. This study was designed to determine the value of rapid detection of pneumococcal antigen in pleural fluid from patients with community acquired pneumonia. METHODS: Thoracentesis was performed in patients suspected of having empyema and in patients with pneumonia of unknown aetiology. Pneumococcal capsular antigen was detected by latex agglutination and this method was compared with Gram staining and culture, specimens of pleural fluid being examined in parallel by the three methods. RESULTS: Pleural fluid was radiographically identified in 63 of 135 patients with community acquired pneumonia. In nine of 45 patients with pneumococcal pneumonia and pleural fluid pneumococci were identified by Gram stain in two and by culture in one specimen of pleural fluid, whereas antigen was detected in eight of these specimens. In 12 of 33 patients with pneumonia of other known aetiology only one pleural fluid specimen was antigen positive, providing a specificity of 92% for this test. Pleural fluid obtained from 12 of 58 patients with pneumonia of unknown aetiology yielded detectable antigen in seven cases. CONCLUSIONS: Detection of pneumococcal antigen by latex agglutination in pleural fluid may yield important and rapid information in patients with community acquired pneumonia.

The role of antigen detection in pneumococcal carriers: a comparison between cultures and capsular antigen detection in upper respiratory tract secretions.

During the winter season upper respiratory tract secretions from 166 patients with stable chronic obstructive pulmonary disease (COPD) or asthma were simultaneously cultured for Streptococcus pneumoniae and tested for pneumococcal capsular antigen. Latex agglutination was employed to investigate the effect of pneumococcal carriership on pneumococcal capsular antigen detection in upper respiratory tract secretions. All specimens originating from the oropharynx, nasopharynx and saliva were both cultured and investigated in parallel for the presence of antigen. The recovery of pneumococci from the different areas was unequally distributed (oropharynx 29%, nasopharynx 8%, and saliva 16%), with the highest isolation rate from the oropharynx alone. Only 4 (3%) of the oropharyngeal swabs, 1 (1%) of the nasopharyngeal swabs and 14 (9%) of the saliva specimens yielded both pneumococcal antigen and a positive culture for S. pneumoniae. A further 9 (6%) of the oropharyngeal swabs, 5 (3%) of the nasopharyngeal swabs, and 50 (33%) of the saliva specimens were antigen positive only, with no pneumococci isolated on culture. It is speculated that these reactions were due to cross-reacting microorganisms (especially alpha-haemolytic streptococci) present in saliva and contaminating the oropharynx and the nasopharynx. Quantitative cultures of 9 oropharyngeal swabs yielded S. pneumoniae in concentrations too low to be detectable by latex agglutination. The study indicates that there is a poor relation between pneumococcal colonization and antigen detection in the oropharynx and nasopharynx. Antigen present in these secretions is probably not an important disrupting factor by contamination when detecting pneumococcal antigen in washed sputum. The false positive antigen results in saliva are probably due to cross-reactions with alpha-haemolytic streptococci.

Detection of pneumococcal capsular antigen in the presence of penicillin in vitro.

Eight strains of Streptococcus pneumoniae were tested in vitro for their ability to produce capsular antigen in the presence of penicillin. It was found that, provided 10(6) to 10(7) pneumococci/ml were present, capsular antigen could be detected during the 72 h in which the experiment was conducted, irrespective of whether penicillin was added at 0 h or 8 h, and even when no viable pneumococci remained. When fewer pneumococci were present, capsular antigen could not be detected at any time in the presence of penicillin. Control cultures, without penicillin, yielded detectable capsular antigen only when the threshold value of 10(6)-10(7) pneumococci/ml was reached. It is concluded that the presence of penicillin does not influence the detection of pneumococcal capsular antigen, but demonstration of this antigen is totally dependent on the number of pneumococci present.

Pneumococcal antigen persistence in sputum from patients with community-acquired pneumonia.

The purpose of this study was to establish the diagnostic value of pneumococcal capsular antigen by comparing this with the results of Gram stain and culture in representative and nonrepresentative sputa during follow-up in patients with community-acquired pneumonia. Antigen was detected by a latex particle agglutination test. At the time of hospital admission, antigen was detected in 17 representative sputum specimens from 30 patients with pneumococcal pneumonia, which was comparable to the results of Gram stain and culture. In five additional patients, antigen was demonstrated in nonrepresentative specimens. During follow-up under antibiotic treatment, this number increased by six: three patients with representative and three patients with nonrepresentative sputum, respectively. Two of the 22 patients with pneumonia of other known cause had an antigen-positive sputum on admission and in another two patients, sputum antigen was detected during follow-up. Ten of 34 patients with pneumonia of unknown cause had detectable antigen in representative or nonrepresentative sputum on admission. During follow-up, antigen was detected in sputa of an additional seven patients. There was no difference in duration of antigen persistence between patients with pneumococcal pneumonia and pneumonia of unknown cause. It was observed that the first antigen-positive sputum specimen was always detected within the first five days of the hospital stay. We conclude that antigen detection in both representative and nonrepresentative sputum specimens at the time of hospital admission and during follow-up is of additional value for the diagnosis of pneumococcal pneumonia. It markedly increases the number of patients with pneumococcal pneumonia detected, who would otherwise be considered to have pneumonia of unknown cause. However, antigen-positive results should be interpreted carefully, especially in those pneumonia patients with chronic bronchitis, because detectable antigen may be caused by pneumococcal carriership of the lower respiratory tract.

Minimum number of pneumococci required for capsular antigen to be detectable by latex agglutination.

Forty-eight strains of Streptococcus pneumoniae were tested in vitro to determine the minimum number required for pneumococcal capsular antigen to be detectable by latex agglutination. It was found that 10(6) to 10(7) microorganisms per ml were needed and that antigen remained detectable even when viable pneumococci could no longer be demonstrated.

Pneumococcal capsular antigen detection and pneumococcal serology in patients with community acquired pneumonia.

BACKGROUND: Methods to determine the microbial cause of community acquired pneumonia include detection of pneumococcal antigen and measurement of pneumococcal capsular antibody response. Their usefulness compared with conventional microbiological techniques was investigated in patients with pneumonia, some of whom had been treated with antibiotics. METHODS: Pneumococcal capsular antigen was detected by latex agglutination in sputum and the results compared prospectively with results of conventional microbiological techniques in 90 patients with community acquired pneumonia. Serum, urine, and pleural fluid samples were also tested for antigen. Serum pneumococcal capsular antibody titres were measured. RESULTS: A diagnosis was established by conventional microbiological techniques in 53 patients, 30 of whom had pneumococcal pneumonia. The sensitivity of antigen detection in first day sputum specimens (n = 18) in those with pneumococcal pneumonia was 94%; antigen was present in 23 of the 27 patients who produced representative sputum on admission and during follow up. The specificity of antigen detection in sputum in patients with non-pneumococcal pneumonia and lung infarction was 87%. Antigen was present in 12 of 25 patients with pneumonia of unknown aetiology who produced representative sputum. Antigen was rarely detected in serum and urine, but was present in pleural fluid in three of four patients with pneumococcal pneumonia and in all four patients with pneumonia of unknown aetiology. Pneumococcal antigen remained detectable in patients treated with antibiotics. Pneumococcal capsular antibody detection was as specific (85%) as antigen detection, but had a lower sensitivity (50%). CONCLUSION: Pneumococcal antigen detection in sputum or pleural fluid is of value in making a rapid diagnosis and provides an additional diagnostic result in patients with pneumococcal pneumonia, especially those receiving antibiotic treatment.