Summer indoor heat exposure and respiratory and cardiovascular distress calls in New York City, NY, U.S.

Most extreme heat studies relate outdoor weather conditions to human morbidity and mortality. In developed nations, individuals spend ~90% of their time indoors. This pilot study investigated the indoor environments of people receiving emergency medical care in New York City, NY, U.S., from July to August 2013. The first objective was to determine the relative influence of outdoor conditions as well as patient characteristics and neighborhood sociodemographics on indoor temperature and specific humidity (N = 764). The second objective was to determine whether cardiovascular or respiratory cases experience hotter and more humid indoor conditions as compared to controls. Paramedics carried portable sensors into buildings where patients received care to passively monitor indoor temperature and humidity. The case-control study compared 338 respiratory cases, 291 cardiovascular cases, and 471 controls. Intuitively, warmer and sunnier outdoor conditions increased indoor temperatures. Older patients who received emergency care tended to occupy warmer buildings. Indoor-specific humidity levels quickly adjusted to outdoor conditions. Indoor heat and humidity exposure above a 26 °C threshold increased (OR: 1.63, 95% CI: 0.98-2.68, P = 0.056), but not significantly, the proportion of respiratory cases. Indoor heat exposures were similar between cardiovascular cases and controls.

Analysis of the recognition mechanism of the alternative pathway of complement by monoclonal anti-factor H antibodies: evidence for multiple interactions between H and surface bound C3b.

The ability of the alternative pathway of complement to discriminate targets as either activators or non-activators is mediated by different binding properties of factor H to surface-associated C3b molecules. In the present study we have probed the interaction between H and C3b using five anti-H mAb. The binding sites of the mAb were mapped by Western blotting using both recombinant and trypsin-generated H fragments. Two mAb bound to CCP1 (90X, 196X), two to CCP5 (MRC OX24, 86X) and one to CCP8-15a (131X). At a molar ratio 2:1 of 125I-H:mAb all tested mAb enhanced binding of H to both activator- and non-activator-bound C3b. At higher concentrations two mAb had an inhibitory effect on H binding to surface-associated C3b (OX24, 131X). Thus the mAb 131X inhibits H binding to surface-bound C3b but unlike OX24 it does not bind to the previously described C3b binding site within or near CCP4-5. These results indicate that there is an additional interaction site on factor H for surface-bound C3b.

Complement activation during painful crisis in sickle cell anemia.

Previous studies documented complement activation in sickle cell disease patients and suggested that this contributes to increased risk of infection. We have demonstrated alternative pathway activation initiated by membrane phospholipid changes which occur in sickled erythrocytes. The present studies compared complement activation products in serial samples from sickle cell anemia patients at baseline and during hospitalization for painful crisis to examine the correlation between complement activation and disease activity. Plasma concentrations of Bb, C4d, and C3a were measured as well as C3 bound to erythrocytes. Patients were subdivided into those with continuous pain and those with intermittent painful episodes. In patients with intermittent pain, there was little evidence of complement activation at baseline and increased plasma concentrations of Bb and C3a during painful crisis. Elevated C3a and C4d levels were observed in patients with continuous pain regardless of hospitalization status, suggesting a continuous underlying inflammatory process in these patients.

Complement activation in cancer patients undergoing immunotherapy with interleukin-2 (IL-2): binding of complement and C-reactive protein by IL-2-activated lymphocytes.

Plasma samples from cancer patients undergoing immunotherapy with high-dose recombinant interleukin-2 (IL-2) were obtained over a 5-day course of treatment and assayed by radioimmunoassay or enzyme-linked immunosorbent assay for the complement degradation products, C3a, iC3b, Ba, Bb, C4d, and SC5b-9. In the majority of patients, pretreatment C3a, Ba, Bb, and SC5b-9 plasma levels were comparable with those measured in normal donor plasma. However, by the end of the 5-day treatment course, C3a levels had increased 15.6-fold. In several patients, peak concentrations of C3a were as high as those reported in patients with sepsis or burn injury. Plasma levels of alternative pathway components Ba and Bb also increased, 8.0- and 5.0-fold, respectively, during IL-2 treatment. Likewise, levels of one of the terminal complexes, SC5b-9, increased 5.0-fold and the plasma C4d and iC3b concentrations increased 4.8- and 2.9-fold, respectively, by the fifth day of treatment. To determine whether activated lymphocytes participate in IL-2-induced complement activation, peripheral blood mononuclear cells (PBMC) obtained from IL-2 recipients before and 5 days after beginning therapy were reacted with monoclonal antibodies (MoAbs) against C3c and the terminal complement complex SC5b-9. Dual-color cytofluorographic analysis showed that within the CD3(+) population, the percentage of cells binding the anti-C3c and anti-SC5b-9 MoAbs increased 6.2-fold and 5.1-fold, respectively, by day 5. The anti-C3c MoAb also bound to CD3(+) cells stimulated in vitro with IL-2 and then exposed to serum. Moreover, fluid-phase iC3b was generated from purified C3 by PBMC activated in vitro with IL-2, but not by unstimulated cells. Serum levels of C-reactive protein (CRP) are markedly elevated in patients undergoing IL-2 immunotherapy. This hepatic acute phase reactant has been shown to activate the classical pathway when bound to cell surfaces. Because levels of the classical component C4d increase markedly during IL-2 treatment, we sought to determine if CRP became bound to PBMC during IL-2 treatment and found that during therapy, the percentage of CD3(+) cells reactive with an anti-CRP MoAb increased from less than 2% to greater than 18%. When PBMC were activated with IL-2 in vitro and then exposed to exogenous CRP, greater than 20% of the CD3(+) cells reacted with the anti-CRP MoAb.(ABSTRACT TRUNCATED AT 400 WORDS)

Plasma terminal complement complexes in acute poststreptococcal glomerulonephritis.

In most instances of acute poststreptococcal glomerulonephritis (APSGN), activation of the complement system occurs, as reflected by decreased levels of the complement proteins C3, C5, and properdin (P). Recent studies implicate terminal complement complexes (TCC) in the pathogenesis of glomerular injury. The fluid phase TCC, SC5b-9, reflects the formation of membrane-bound C5b-9 and has been used as a clinical marker in various diseases. Plasma concentrations of SC5b-9 were measured with an enzyme immunoassay using a monoclonal antibody to a neoantigen expressed on the SC5b-9 complex in 13 children who presented with clinical and pathologic features of APSGN. SC5b-9 was significantly elevated in all plasmas obtained within 30 days after onset of clinical glomerulonephritis. Concentrations of SC5b-9 in acute plasmas were significantly higher than those of paired convalescent samples. For individual patients, as SC5b-9 concentration returned to normal there was a coincident decrease in serum creatinine concentration and urinary protein excretion, signifying clinical improvement in glomerulonephritis. Thus, TCC generation commonly occurs in the early stages of APSGN and may be of importance in the pathogenesis of the condition.

Ba and Bb fragments of factor B activation: fragment production, biological activities, neoepitope expression and quantitation in clinical samples.

Factor B is a centrally important component of the alternative complement pathway. Alternative pathway activation results in factor B cleavage and production of the amino-terminal Ba and the carboxyl-terminal Bb fragments which have molecular weights of approximately 30,000 and 63,000 daltons, respectively. Both Ba and Bb fragments have been reported to express a variety of biological activities in vitro. Thus, binding of Ba and Bb fragments to specific B lymphocyte surface receptors modulates proliferation of prestimulated B cells. In addition, the enzymatically active Bb fragment induces activation and spreading of human and murine macrophages and monocytes as well as regulates C5a des Arg chemotactic activity. The fractional catabolic rate and metabolism of factor B in vivo is similar to that of C3, C4 and C5 complement proteins, which are among the most metabolically active plasma proteins in the circulatory system. Factor B hyperconsumption and increased catabolism, concomitant with factor B fragment production, occurs in a wide variety of diseases, including gram-negative sepsis, autoimmune diseases and burns. Measurement of alternative pathway activation in vivo has been attempted utilized a number of different techniques to quantitate factor B fragments in biological fluids. However, the recent development of enzyme immunoassays (EIA) employing monoclonal antibodies (MoAbs) reactive with factor B fragment neoepitopes provides the best approach currently available for the quantitation of factor B activation fragments. Results obtained using these new MoAb-based EIAs have indicated that factor B fragment concentrations were elevated, as compared with normal donor levels, in EDTA plasma samples obtained from patients with rheumatoid arthritis and systemic lupus erythematosus (SLE). Plasma concentrations of factor B fragments, especially Ba fragment levels, in these patients showed a positive correlation with disease activity scores. One of the highest disease activity correlations was obtained with Ba fragment measurements in SLE plasma samples. In fact, the results strongly suggested that quantitation of Ba fragment levels in SLE plasma samples more accurately reflected disease activity and was a more sensitive predictor of impending flare in these patients than any other test(s) currently available.

Biological effects of short-term, high-concentration exposure to methyl isocyanate. VI. In vitro and in vivo complement activation studies.

The ability of MIC to induce complement activation in vitro and in vivo was investigated. For the in vitro studies, both human and guinea pig serum or EDTA-plasma samples were exposed to 1167 to 1260 ppm MIC vapor for 15 min at room temperature. The human serum samples exposed to MIC showed significant reductions in Factor B, C2, C4, C3, C5, and total hemolytic complement CH50 activity levels. C6 functional activity was unaffected. The C3, C5, and CH50 functional activities in guinea pig serum (the only functional tests conducted on these samples) were more sensitive to MIC-mediated reduction than the corresponding activity reductions observed in the human serum samples. The human and single guinea pig EDTA-plasma samples exposed to MIC vapor showed no evidence of C3 consumption but did show significant reductions in CH50 levels. Thus, MIC vapor was able to activate, and thereby reduce serum complement C3 activity in vitro by a complement-dependent process. However, the data suggest at least one complement component other than C3 was inactivated in EDTA-plasma by a complement-independent mechanism. For the in vivo studies, five pairs of guinea pigs were exposed to 644 to 702 ppm MIC vapor until one of the pair died (11-15 min). MIC exposure was then discontinued, the surviving guinea pig was sacrificed, and EDTA-plasma was obtained from both animals and analyzed for complement consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of an antigenic epitope and receptor binding domain of human C5a.

Nine different murine anti-human C5a monoclonal antibodies have been produced and characterized. They exhibit Kas for the 125I-labeled ligand that range from 0.4 to 48 X 10(8) M-1, and they display limited cross-reactivity with C5a from other species. Each of these antibodies has been found to compete with the granulocyte C5a receptor for binding site(s) on the C5a polypeptide. Exploration of the antigenic topography of C5a revealed that the immunodominant portion of this glycopolypeptide resides between residues Lys20 and Arg37, with the area surrounding Cys27 being particularly important. In addition, a specific C5a derived tryptic peptide containing these amino acid residues competes with 125I-C5a for binding to the receptor. These observations are consistent with previously published data and suggest that this area of the C5a molecule is an important part of the receptor "recognition domain", and thus plays a critical role in the C5a receptor interaction.

Direct quantitation of activated C3 in human plasma with monoclonal anti-iC3b-C3d-neoantigen.

We developed a microtiter solid-phase radioimmunoassay for quantitating C3 breakdown products (iC3b, C3dg, C3d) in human plasma with a unique monoclonal antibody specific for a neoantigen present on iC3b and C3d (MoAb 130). This monoclonal antibody reacts with a neoantigen which appears when C3b is converted to iC3b. The neoantigen is also present on the C3dg and C3d fragments derived from iC3b. The concentration of the neoantigen is elevated in the plasma of most patients with rheumatoid arthritis and systemic lupus erythematosus as compared to normal volunteers. Some patients with glomerulonephritis also had elevated concentration of the neoantigen in their plasma.

Monoclonal antibodies against complement 3 neoantigens for detection of immune complexes and complement activation. Relationship between immune complex levels, state of C3, and numbers of receptors for C3b.

C3-bearing immune complexes and C3 activation products were detected by using two monoclonal antibodies, one specific for a neoantigenic determinant on C3c and the other for C3d. To quantitate immune complexes, the anti-C3c or anti-C3d antibodies were fixed to microtiter plates and reacted with test plasma. The binding of C3-bearing immune complexes in this plasma was then measured with radioisotope- or enzyme-labeled anti-human IgG. To test for C3 breakdown products, solid-phase monoclonal antibody to the C3d neoantigen was reacted with EDTA-plasma samples, and fixed iC3b or C3d was measured with a polyclonal anti-C3 antibody. Patients with autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Sjogren's syndrome, and paracoccidioidomycosis were found to contain immune complexes bearing C3b/iC3b or C3d. In most conditions, there were more C3d-containing immune complexes than C3b/iC3b. Although CR1 (C3b receptors) rapidly converted immune complex-bound iC3b to C3dg/C3d and lupus patients had reduced CR1, no correlation between the state of C3 on circulating immune complexes or levels of immune complexes and CR1 numbers was seen. However, levels of C3-fixing ICs correlated with levels of C3 activation products. This assay system with monoclonal antibodies to neoantigens expressed on activated, but not native, C3 provides sensitive and specific means for detecting and classifying C3-fixing immune complexes and for assessing C3 activation.

Detection of a neoantigen on human C3bi and C3d by monoclonal antibody.

A neoantigen was detected on human C3bi and C3d by using the monoclonal antibody (MoAb) 130. The antibody bound to EC3bi and EC3d cells but not to EC3b. Although highly purified C3bi or C3d strongly inhibited the binding of the antibody to EC3d, highly purified C3c had no such effect. Native C3, C3b, or C3(H2O) inhibited this binding only weakly. The neoantigen was also detected in serum after activation with zymosan or heat-aggregated IgG, and it was found bound to the aggregated IgG and zymosan particles. Plasma samples from patients with immunologic disorders were tested for this neoantigen, and 25 out of 43 samples tested were found to have levels of neoantigen corresponding to 2 to 11.5% complement activation, whereas 13 out of 14 normal donor plasmas contained amounts of neoantigen indicating much less than 1% complement activation.

Platelet-associated complement in chronic ITP.

Chronic ITP is due to antibody-induced destruction of platelets by the reticuloendothelial (RE) system. The role of complement in this process is unclear. We measured platelet-associated complement (PAC) components C3, C3bi, C4 and C9 in 16 patients with chronic ITP, in two of these patients prior to and after splenectomy. Competitive solid-phase radioimmunoassays using monoclonal antibody (anti-C3d, anti-C3bi neoantigen or anti-C9) or affinity-purified heterologous antibody (anti-C4) were used. Mean values (+/- SD) of normal subjects (ng/10(7) plts) were: PAC3d 17.6 +/- 6.8; PAC3bi 11.6 +/- 2.3; PAC4 1.6 +/- 0.5; PAC9 9.9 +/- 2.6. Significantly elevated (greater than 2 SD) PAC3, PAC3bi, PAC4 and PAC9 levels occurred in 12/16, 11/14, 10/14 and 5/9 chronic ITP patients. The PAC3, PAC3bi and PAC9 values correlated inversely with the patients' platelet counts (P less than 0.001); PAC4 levels did not. A positive correlation was also noted between PAC3, PAC3bi and PAC9 while PAC4 values showed no correlation. Two patients with preoperative elevation of all four PAC proteins showed normalization of PAC3, PAC3bi and PAC9 values after a splenectomy-induced remission; PAC4 levels remained elevated for up to 5 months after surgery. We conclude that in vivo C activation occurs in most chronic ITP patients with binding of C3 and C9 to the platelet surface. This in vivo C activation may promote more efficient phagocytosis (C3b) and possibly platelet lysis (C5-9) in some ITP patients.

An enzyme-linked immunosorbent assay for platelet compatibility testing.

The selection of platelet donors for patients who are refractory to random donor platelets often presents a difficult clinical problem. We describe an enzyme-linked immunosorbent assay (ELISA) for evaluating alloantibodies in refractory patients. Platelets from prospective donors are immobilized on microtiter plates and, after incubation with test serum and washing, platelet-bound IgG is detected with enzyme-linked anti-human IgG. Platelets from 46 prospective donors were tested. Twenty-two were judged compatible (reciprocal of the antibody titer less than 16) and, of these, 15 were used as platelet donors; each gave a measurable platelet increment after transfusion. The magnitude of the response was roughly proportional to the assay results. Platelets from donors giving antibody titers less than 4 resulted in platelet increments at 1 hr ranging from 4,890 to 22,200 (median 12,600), while platelets from donors giving titers of 8 or 16 resulted in lesser increments (550-4548). Conversely, 5 of the 24 patients found incompatible by the assay (titer greater than 16) gave no platelet increment, and in 3 instances, the recipient developed fever and chills after the transfusion. The assay is sensitive, simple, and adaptable to the clinical laboratory. Platelets from volunteer donor panels can be plated and stored for up to 6 mo.

Indirect 125I-labeled protein A assay for monoclonal antibodies to cell surface antigens.

An assay for detection of monoclonal hybridoma antibodies against cell surface antigens is described. Samples of spent medium from the hybridoma cultures are incubated in microtest wells with cells, either as adherent monolayers or in suspension. Antibodies bound to surface antigens are detected by successive incubations with rabbit anti-immunoglobulin serum and 125I-labeled protein A from Staphylococcus aureus, followed by autoradiography of the microtest plate or scintillation counting of the individual wells. Particular advantages of this assay for screening hybridomas are: (1) commerically available reagents are used, (2) antibodies of any species and of any immunoglobulin class or subclass can be detected, and (3) large numbers of samples can be screened rapidly and inexpensively. We have used the assay to select hybridomas producing monoclonal antibodies to surface antigens of human melanomas and mouse sarcomas.

Regression and inhibition of sarcoma growth by interference with a radiosensitive T-cell population.

BALB/c mice were inoculated subcutaneously with 10(6) cells from either of two syngeneic sarcomas 1315 and 1425. 6--8 days later, the mice were randomized into groups which were left untreated or given 400 rads of whole body irradiation. Irradiation significantly retarded the growth of both sarcomas, and complete regressions were seen of approximately equal to 30% of the small, established 1315 tumors. The anti-tumor effect of irradiation was abolished if the irradiated mice were inoculated with a T-cell-enriched (but not with a T-cell deprived) suspension of syngeneic spleen cells, suggesting that the irradiation inhibited tumor growth by affecting a radiosensitive population of host suppressor T cells.

An isotope-release assay and terminal-labeling assay for measuring cell-mediated allograft and tumor immunity to small numbers of adherent target cells.

A 51Cr-release assay and terminal 51Cr-labeling assay for measuring cell-mediated immunity to adherent target cells is described. Both techniques utilize small 10 microliter-per well microtiter plates, require low numbers of target cells (50-500 per well), and consequently, relatively small numbers of effector cells per well (3x10(3) -1x10(5)). Both assays are objective, quantitative, and simple to perform. The suitability of these techniques for monitoring immunologically specific, cellmediated, cytotoxic response to syngeneic and allogeneic tumor cells and normal skin fibroblasts is demonstrated. Lymph node cells, spleen cells and peritoneal exudate cells serve as effectors.