Specific effects on human neutrophils of antibodies to a membrane protein constituent of neutrophil receptors for chemotactic formyl-methionyl peptides

IgG and Fab were prepared from goat antisera to MP-2, the quantitatively predominant membrane protein constituent of human neutrophil receptors for chemotactic formyl-methionyl peptides. Only 10%–25% of the f-Met-Leu-Phe combining sites of MP-2 purified from neutrophil membranes that had been solubilized in Nonidet P40 exhibited binding constants similar in magnitude to those of the receptors in intact neutrophils, while the remainder of the sites retained a mean of 2% of the affinity of native receptors. Purified MP-2 elicited IgG antibodies predominantly to framework determinants, rather than the combining site, of the f-Met-Leu-Phe receptors. IgG antibodies, but not Fab, evoked the release of significant quantities of β-glucuronidase and lysozyme from neutrophils. Saturating concentrations of Fab bound to a mean of 65,000 determinants per neutrophil, as assessed with ¹²⁵I-Fab, but failed to stimulate neutrophil chemotaxis or chemokinesis, and inhibited by 15% or less the binding of [³H]f-Met-Leu-Phe to intact neutrophils. Fab of anti-MP-2 inhibited neutrophil chemotactic responses to f-Met-Leu-Phe by up to 80%, without influencing the responses to equally chemotactic concentrations of fragments of C5 and of leukotriene B₄. Preincubation of neutrophils for 2–30 min at 37° with concentrations of f-Met-Leu-Phe which suppressed significantly the number of receptors available to [³H]f-Met-Leu-Phe, increased the number of receptors detected by ¹²⁵I-Fab of anti-MP-2, while neither fragments of C5 nor leukotriene B₄ altered the number of receptors determined by either assay. Antibodies to non-combining site determinants of chemotactic peptide receptors provide a novel immunospecific probe for studies of the regulation of neutrophil chemotaxis.     

Nondetection of the S antigen due to the presence of sodium hypochlorite

Low concentrations of sodium hypochlorite (chlorine bleach) are known to destroy S antigen on intact fresh red blood cells (RBCs). Sodium hypochlorite is commonly used as a disinfectant. We report nondetection of the S antigen in tube and microplate saline indirect antiglobulin testing (SIAT) with a lot of commercial saline utilized in our donor screening and reference laboratories. Known S+s+ RBCs were found to be nonreactive with anti-S by SIAT in our reference laboratory. Our investigation demonstrated the presence of chlorine in the commercial saline. The saline lot was used for several days of donor screening and recall of FFP and platelet concentrates was initiated. Two lots of saline were recalled from blood banks across North America.     

A computer protocol to predict myocardial infarction in emergency department patients with chest pain

To achieve more appropriate triage to the coronary care unit of patients presenting with acute chest pain, we used clinical data on 1379 patients at two hospitals to construct a simple computer protocol to predict the presence of myocardial infarction. When we tested this protocol prospectively in 4770 patients at two university hospitals and four community hospitals, the computer-derived protocol had a significantly higher specificity (74 vs. 71 percent) in predicting the absence of infarction than physicians deciding whether to admit patients to the coronary care unit, and it had a similar sensitivity in detecting the presence of infarction (88.0 vs. 87.8 percent). Decisions based solely on the computer protocol would have reduced the admission of patients without infarction to the coronary care unit by 11.5 percent without adversely affecting the admission of patients in whom emergent complications developed that required intensive care. Although this protocol should not be used to override careful clinical judgment in individual cases, the computer protocol for the most part yields accurate estimates of the probability of myocardial infarction. Decisions about admission to the coronary care unit based on the protocol would have been as effective as those actually made by the unaided physicians who cared for the patients, and less costly. Whether physicians who are aided by the protocol perform better than unaided physicians cannot be determined without further study.     

Differential effects of pentoxifylline on the production of tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) by monocytes and T cells.

Pentoxifylline (PTX) is a methylxanthine compound known to inhibit the production of tumour necrosis factor-alpha (TNF-alpha) by monocytic cells. In this study, we found that PTX differentially regulates the production of TNF-alpha and interleukin-6 (IL-6). Indeed, PTX at high concentrations triggers the production of IL-6 but not of TNF-alpha by peripheral blood mononuclear cells (PBMC). Further experiments indicated that monocytes are responsible for this PTX-induced IL-6 production. When PBMC were stimulated with LPS, PTX was found to inhibit the secretion of TNF-alpha as well as the accumulation of TNF-alpha messenger RNA (mRNA). In contrast, no inhibitory effect was observed on the induction of IL-6. Similar results were obtained when PBMC were stimulated with OKT3 monoclonal antibody (mAb). In addition, the in vivo administration of PTX in transplant patients receiving the first dose of OKT3 allowed to decrease the systemic release of TNF-alpha but not of IL-6. Since monocytes represent a major source of TNF-alpha and IL-6 in these settings, additional experiments were performed in vitro on purified T cells stimulated with the CLB-T3/3, an anti-CD3 mAb which does not require the presence of accessory cells to activate T cells. In this system, PTX was found to inhibit the secretion of both TNF-alpha and IL-6 by T cells. We suggest that cAMP could be involved in these differential effects of PTX on production of TNF-alpha and of IL-6.     

Relationship between phagocytosis and immunoglobulin A release from human colostral macrophages.

Macrophages and neutrophils that contain mainly secretory immunoglobulin A (IgA) comprise the majority of cells in human colostrum. These cell populations were separated and analyzed for their ability to release total IgA and secretory IgA when stimulated to phagocytose. Colostral macrophages phagocytosed opsonized bacteria and nonopsonized latex particles; at the same time, IgA was released. Neutrophils poorly phagocytosed opsonized bacteria but actively phagocytosed latex particles. In contrast to the macrophages, the neutrophils did not release IgA, even after active phagocytosis of latex. Consequently, colostral macrophages are the main source of IgA released from colostral leukocytes when these cells are exposed to organisms or particles that are phagocytosed. A function for colostral neutrophils which sequester IgA is proposed.     

National hospital survey of anaerobic culture and susceptibility testing methods: results and recommendations for improvement.

The methods for performing anaerobic bacterial isolation and identification continue to change and improve. Anaerobic susceptibility testing has become controversial, and method-dependent variability has been noted. To assess the status of clinical anaerobic bacteriology in the United States, we surveyed, by means of a questionnaire, 120 hospitals, selected at random, with bed capacities of 200 to 1,000, and we received responses from 88 (73%). All hospitals performed cultures for anaerobes. The media and methods used for transport, initial processing, incubation, and identification varies between the different regions in the United States. Thirty percent of laboratories did not perform susceptibility studies, 16% used a reference laboratory, and 54% performed them in house. For half the laboratories, susceptibility testing was performed on isolates depending on the source; in this case, blood cultures were tested by 97% of the laboratories, serious infections were tested by 60%, sterile body sites were tested by 73%, pure cultures were tested by 47%, and tests were done by physician request by 39%. For laboratories doing testing, the broth disk method, no longer sanctioned by the National Committee for Clinical Laboratory Standards, was used most often (56%), followed by microdilution (33%), beta-lactamase testing (25%), macrotube dilution (2%), and agar dilution (2%). The antimicrobial agents tested were as follows: penicillin-ampicillin, 94%; clindamycin, 94%, metronidazole, 90%; chloramphenicol, 80%; cefoxitin, 76%; tetracyclines, 51%; and erythromycin, 45%. All other agents were tested by less than or equal to 25% of laboratories; the methods used could be improved to make the results more timely and consequently more clinically relevant.     

Increased sharing of maternal HLA haplotypes among children exposed to diphenylhydantoin during pregnancy.

During investigation of HLA types among children exposed to diphenylhydantoin (DPH) in utero, we found no evidence of a distortion in haplotype sharing among affected sib pairs. Unexpectedly, however, we found a marked increase in the proportion of all sib pairs (not just affected ones) sharing maternal haplotypes. Among 14 two child families, 12 shared the maternal haplotype (expected would be seven); among families with more than two children the distortion was also pronounced. This finding, if verified in future studies, could indicate that something in the mothers, whether DPH use during pregnancy, or some genetic factor associated with seizures, or some effect of the seizures themselves, may be leading to non-random segregation of HLA haplotypes in their offspring.     

The immunoglobulins in Hodgkin's disease

Immunoglobulins have been measured in fifty patients with Hodgkin's disease. Levels of γG were slightly raised as compared with a control population, but γA tended to be low and γM was generally at or below our lower limit of normal. These findings are discussed in relation to the duration of the disease, its clinical staging, and the possible effects of radiotherapy and chemotherapy.

It is suggested that the reduced γM levels are due to decreased synthesis in the reticulo-endothelial system rather than to increased catabolism. Reference is made to the depression in delayed-type hypersensitivity found early in Hodgkin's disease and this and reduction in γM levels may both reflect the same derangement in lymphoid cells.

The detection of α₃-globulin in the sera of 62 per cent of the patients is referred to and its association with other neoplastic reticuloses is emphasized.

     

Life expectancy in British Marfan syndrome populations

A total of 206 patients with Marfan syndrome were ascertained throughout genetic clinics in Wales and Scotland during the period 1970–1990. There were 45 deaths representing 22% of the cohort. Mean age at death was 45.3 ± 16.5 years. 50% median cumulative survival in the total cohort (n = 206) was 53 years for males and 72 years for females. Multivariate analysis confirmed severity as the best independent indicator of survival. These findings and survival curves will assist in the counselling of British families and individuals with Marfan syndrome.