The serpin-enzyme complex (SEC) receptor mediates the neutrophil chemotactic effect of alpha-1 antitrypsin-elastase complexes and amyloid-beta peptide.

The serpin-enzyme complex (SEC) receptor mediates catabolism of alpha 1-antitrypsin (alpha 1-AT)-elastase complexes and increases in synthesis of alpha 1-AT in cell culture. The SEC receptor recognizes a pentapeptide domain on alpha 1-AT-elastase complexes (alpha 1-AT 370-374), and the same domain in several other serpins, amyloid-beta peptide, substance P, and other tachykinins. Thus, it has also been implicated in the biological properties of these ligands, including the neurotoxic effect of amyloid-beta peptide. In this study, we examined the possibility that the SEC receptor mediates the previously described neutrophil chemotactic activity of alpha 1-AT-elastase complexes, and whether the other ligands for the SEC receptor have neutrophil chemotactic activity. The results show that 125I-peptide 105Y (based on alpha 1-AT 359-374) binds specifically and saturably to human neutrophils, and the characteristics of this binding are almost identical to that of monocytes and hepatoma-derived hepatocytes. Peptide 105Y and amyloid-beta peptide mediate chemotaxis for neutrophils with maximal stimulation at 1-10 nM. Mutant or deleted forms of peptide 105Y, which do not bind to the SEC receptor, have no effect. The neutrophil chemotactic effect of alpha 1-AT-elastase complexes is blocked by antiserum to peptide 105Y and by antiserum to the SEC receptor, but not by control antiserum. Preincubation of neutrophils with peptide 105Y or substance P completely blocks the chemotactic activity of amyloid-beta peptide, but not that of FMLP. These results, therefore, indicate that the SEC receptor can be modulated by homologous desensitization and raise the possibility that pharmacological manipulation of this receptor will modify the local tissue response to inflammation/injury and the neuropathologic reaction of Alzheimer's disease.

Pulmonary squamous cell carcinoma following head and neck squamous cell carcinoma: metastasis or second primary?

PURPOSE: To distinguish a metastasis from a second primary tumor in patients with a history of head and neck squamous cell carcinoma and subsequent pulmonary squamous cell carcinoma. EXPERIMENTAL DESIGN: For 44 patients with a primary squamous cell carcinoma of the head and neck followed by a squamous cell carcinoma of the lung, clinical data, histology, and analysis of loss of heterozygosity (LOH) were used to differentiate metastases from second primary tumors. RESULTS: Clinical evaluation suggested 38 patients with metastases and 6 with second primaries. We developed a novel interpretation strategy based on biological insight and on our observation that multiple LOH on different chromosome arms are not independent. LOH analysis indicated metastatic disease in 19 cases and second primary squamous cell carcinoma in 24 cases. In one case, LOH analysis was inconclusive. For 25 patients, LOH supported the clinical scoring, and in 18 cases, it did not. These 18 discordant cases were all considered to be second primary tumors by LOH analysis. CONCLUSIONS: A considerable number of squamous cell lung lesions (50% in this study), clinically interpreted as metastases, are suggested to be second primaries by LOH analysis. For these patients, a surgical approach with curative intent may be justified.

8-Bromo-adenosine 3',5'-monophosphate regulates expression of chorionic gonadotropin and fibronectin in human cytotrophoblasts.

Addition of 8-bromo-cAMP to primary cultures of human placental cytotrophoblasts results in significant alterations in the synthesis of secreted proteins, as detected by labeling with pulses of [35S]methionine. Using immunoprecipitation techniques, we demonstrated that exposure to 8-bromo-cAMP prevented the de novo synthesis and secretion of the extracellular matrix component fibronectin, but enhanced the production of hCG subunits. The effects of the cyclic nucleotide on synthesis and secretion of these proteins were evident within 24 h. 8-Bromo-cAMP increased the cellular content of mRNA encoding the hCG alpha- and beta-subunits and prevented the increase in fibronectin mRNA, as determined by blot hybridization analysis using specific cDNA probes. These findings demonstrate that cyclic nucleotides regulate the synthesis of several specific proteins in cultured human trophoblast by regulating levels of the mRNAs encoding the proteins. The actions of cyclic nucleotides in this regard may be essential for the normal expression of trophoblast endocrine function.

Expression of low density lipoprotein receptor in cultured human granulosa cells: regulation by human chorionic gonadotropin, cyclic AMP, and sterol.

Steroidogenic cells utilize lipoprotein-delivered cholesterol as a primary substrate for hormone synthesis. We studied low density lipoprotein (LDL) receptors in cultured human granulosa cells to determine what factors regulate receptor expression. Granulosa cells cultured under serum-free conditions were treated with human chorionic gonadotropin (hCG) for 1.5 to 14 hr. The LDL receptor content of cells increased by approximately twofold within 6 hr of hCG treatment, and the content continued to increase for at least 14 hr, as determined by immunoblotting. The rate of LDL receptor synthesis was also demonstrated to increase within 2.5 to 3.5 hr of hCG treatment by immunoisolation of LDL receptor from cells metabolically labeled with a pulse of [35S]methionine. The cyclic AMP analogue, 8-bromo-cAMP, was also found to increase LDL receptor synthesis. This increased rate of synthesis was shown to be dependent on ongoing RNA synthesis, since actinomycin D abolished hCG- or 8-bromo-cAMP-stimulated LDL receptor synthesis. We also demonstrated that hCG- and 8-bromo-cAMP-mediated regulation of LDL receptor synthesis in granulosa cells supersedes the classical cholesterol-mediated regulation of the receptor described in fibroblasts. Although 25-hydroxycholesterol induced a decrease in LDL receptor content and synthesis within 6 hr, this action was overridden by simultaneous exposure to hCG. Our findings demonstrate the existence of a novel cAMP-mediated mechanism for regulation of LDL receptor synthesis in steroidogenic cells.

T lymphocyte subpopulations in congenital cytomegalovirus infection.

T lymphocyte subpopulations in the peripheral blood of children with congenital cytomegalovirus infections and in controls were enumerated with monoclonal antibodies. Infants of less than 1 year of age with symptomatic infections showed significant increases in the proportion of suppressor cells and decreases in the ratio of helper to suppressor cells, whereas T lymphocyte populations in older symptomatic patients and asymptomatic infants and children did not differ from those in controls.

Antibody response to cytomegalovirus after renal transplantation: comparison of patients with primary and recurrent infections.

The specific antibody response of 22 renal transplant patients with primary cytomegalo-virus (CMV) infection was compared to that of 21 patients with recurrent infection using seven different techniques to measure antibody. With primary infection seroconversion occurred between two and 12 weeks postoperatively, and geometric mean titers increased rapidly during this interval with each test except virus neutralization. In the group with recurrent CMV infection, geometric mean titers declined slightly initially and then increased rapidly to reach peak levels by 10 weeks. In both primary and recurrent infections, IgM antibody was detectable by radioimmunoassay and indirect immunofluorescence; the former procedure was clearly the more sensitive. After absorption to remove rheumatoid factor, 20 of the 22 patients with primary infection and eight of the 21 with recurrent infection had IgM antibody to CMV by radioimmunoassay which often persisted for over six months. The former group had significantly more viremia and symptomatic infections than the latter. Two critically ill patients failed to develop IgM or neutralizing antibody.

Specific lymphocyte blastogenic responses in children with cytomegalovirus and herpes simplex virus infections acquired early in infancy.

Cell-mediated immune responses in 27 infants and children with cytomegalovirus (CMV) infection acquired between birth and 1 year of age were compared with responses in 13 children who had neonatal herpes simplex virus (HSV) infection. Infection was asymptomatic in 25 of 27 CMV-infected children; the 13 patients with HSV infection were all ill as newborns. The median age when studied was 46 months for children infected with CMV and 24 months for those infected with HSV. We measured lymphocyte transformation responses (LTRs) to CMV antigens in the former group and to HSV type 1 (HSV-1) (and in six cases to HSV-2) in the latter group, with the results expressed as a stimulation index. Based on the results in seropositive and seronegative adult control subjects, stimulation indexes of greater than or equal to 3 were considered indicative of a positive LTR. Among the CMV-infected children, a positive LTR was observed in 0 to 13 assays performed before 1 year of age, 3 of 8 assays performed between 1 and 4 years of age, and 9 of 15 assays performed over 4 years of age. In contrast, a positive LTR to HSV-1 was seen in 15 to 18 assays performed in children under 1 year of age and in 14 of 16 assays performed in survivors of neonatal HSV infection older than 1 year. Six HSV-2-infected patients were tested simultaneously 13 times with HSV-1 and HSV-2 antigens. Those patients under 6 months of age responded similarly to each antigen, whereas those who were older had significantly higher LTRs to HSV-2. Children with CMV infection that was acquired early had persistently diminished specific LTRs. In contrast, after neonatal HSV infection, LTRs to HSV were present even in infancy and became more specific for the infecting type with increasing age.