Properdin, a positive regulator of complement activation, is released from secondary granules of stimulated peripheral blood neutrophils

Properdin is an important regulatory constituent of the complement system. In contrast to most other components of complement, biosynthesis of properdin is restricted to a few cell types only, i.e., monocytes/macrophages and peripheral blood T cells. This report demonstrates the presence of properdin mRNA in peripheral blood granulocytes and shows that properdin is stored in the granules of human neutrophils and secreted upon stimulation with TNF-alpha, C5a, IL-8, or FMLP. Subcellular fractionation using Percoll density gradients and Western blot analyses revealed that the bulk of properdin is contained in the secondary granules. Moreover, flow cytometric analyses indicated that properdin is present on the surface of neutrophils. In contrast to alternative pathway components, components of the classical pathway of complement activation, such as C2 and C4, were not detected. Our findings suggest that neutrophils can actively stabilize and amplify the alternative activation pathway of complement by secretion of properdin as part of the innate defense against microorganisms.

Systematic implementation of an advance health care directive in the community

In Canada, advance directives have been developed to ensure individual's decisions about health care are known in the event of mental incapacity. This randomized control trial examined the proportion of chronically ill elders receiving Victorian Order of Nurses (VON) services in the home who would complete an advance directive, factors associated with directive completion, treatment choices, and satisfaction with care. The participants consisted of 163 elders with a chronic illness residing within the Hamilton-Wentworth and Haldimand-Norfolk regions in South Central Ontario. Seventy percent of the experimental group completed the directive. Younger patients (p = 0.01) and patients with particular nurses (p = 0.04) were more likely to complete a directive. Psychosocial variables such as mood, depression, and uncertainty in illness did not influence directive completion. Satisfaction with involvement in health care decisions was not changed by this intervention (p = 0.576).

Properdin, a positive regulator of complement activation, is released from secondary granules of stimulated peripheral blood neutrophils

Properdin is an important regulatory constituent of the complement system. In contrast to most other components of complement, biosynthesis of properdin is restricted to a few cell types only, i.e., monocytes/macrophages and peripheral blood T cells. This report demonstrates the presence of properdin mRNA in peripheral blood granulocytes and shows that properdin is stored in the granules of human neutrophils and secreted upon stimulation with TNF-alpha, C5a, IL-8, or FMLP. Subcellular fractionation using Percoll density gradients and Western blot analyses revealed that the bulk of properdin is contained in the secondary granules. Moreover, flow cytometric analyses indicated that properdin is present on the surface of neutrophils. In contrast to alternative pathway components, components of the classical pathway of complement activation, such as C2 and C4, were not detected. Our findings suggest that neutrophils can actively stabilize and amplify the alternative activation pathway of complement by secretion of properdin as part of the innate defense against microorganisms.

Synthesis of classical pathway complement components by chondrocytes

Using immunohistochemical studies, C1q, C1s, C4 and C2 were detected in chondrocytes in normal human articular cartilage and macroscopically normal articular cartilage from the inferior surfaces of hip joints of patients with osteoarthritis. Using reverse-transcribed polymerase chain reaction (RT-PCR), mRNA for C1q, C1s, C4 and C2 was also detected in RNA extracted from articular cartilage. C1r, C3, C1-inhibitor, C4-binding protein and factor I were not detected by either technique. Articular chondrocytes cultured in vitro synthesized C1r, C1s, C4, C2, C3 and C1-inhibitor but not C1q, C4-binding protein or factor I, as assessed by enzyme-linked immunosorbent assay (ELISA) and Northern blot analysis. Thus cultured articular chondrocytes have a complement profile that is similar to that of cultured human fibroblasts rather than that of articular chondrocytes in vivo. Complement synthesis in cultured chondrocytes was modulated by the cytokines interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), showing that cytokines can probably regulate complement synthesis in intact cartilage. The possible roles of local synthesis of complement components by chondrocytes in matrix turnover and the regulation chondrocyte function are discussed.

Epitope mapping of C1 inhibitor autoantibodies from patients with acquired C1 inhibitor deficiency

We report six patients with acquired C1 inhibitor (C1-inh) deficiency associated with serum C1-inh autoantibodies and circulating cleaved (96 kDa), functionally inactive C1-inh. In three patients, all of whom had IgG-kappa paraproteins in their sera, the Abs were IgG-kappa. In the remaining three patients, the Abs were IgM (2 kappa, 1 lambda). These data suggest that all the Abs were monoclonal. The autoantibodies recognized two synthetic peptides (peptides 2 and 3), which spanned the reactive center of C1-inh. Binding to peptide 3 (residues 448-459) was greater than to peptide 2 (residues 438-449), suggesting that the epitope recognized by the autoantibodies was expressed principally by peptide 3. Both peptides inhibited the binding of the autoantibodies to C1-inh. None of the autoantibodies recognized peptide 1 (residues 428-440), and this peptide did not inhibit the binding of the autoantibodies to C1-inh. The use of substituted peptides suggested that residues Q452 and Q453 made significant contributions to the epitope, and computer modeling studies showed their side chains to be surface exposed in the intact molecule. However, computer modeling also showed that none of the side chains of the polar residues in peptide 2 were sufficiently close to Q452 and Q453 to be able to contribute to a shared epitope. As peptide 2 could inhibit the binding of C1-inh autoantibodies to peptide 3 and vice versa, we conclude that an autoepitope also exists in peptide 2. Computer modeling and the use of substituted peptides suggested that the sequence LLVF (residues 446-449) in peptide 2 is structurally similar to the sequence QQPF (residues 452-455) in peptide 3. We therefore conclude that there are two potential epitopes in the intact C1-inh molecule that are capable of binding to C1-inh autoantibodies.

Epitope mapping of C1 inhibitor autoantibodies from patients with acquired C1 inhibitor deficiency

We report six patients with acquired C1 inhibitor (C1-inh) deficiency associated with serum C1-inh autoantibodies and circulating cleaved (96 kDa), functionally inactive C1-inh. In three patients, all of whom had IgG-kappa paraproteins in their sera, the Abs were IgG-kappa. In the remaining three patients, the Abs were IgM (2 kappa, 1 lambda). These data suggest that all the Abs were monoclonal. The autoantibodies recognized two synthetic peptides (peptides 2 and 3), which spanned the reactive center of C1-inh. Binding to peptide 3 (residues 448-459) was greater than to peptide 2 (residues 438-449), suggesting that the epitope recognized by the autoantibodies was expressed principally by peptide 3. Both peptides inhibited the binding of the autoantibodies to C1-inh. None of the autoantibodies recognized peptide 1 (residues 428-440), and this peptide did not inhibit the binding of the autoantibodies to C1-inh. The use of substituted peptides suggested that residues Q452 and Q453 made significant contributions to the epitope, and computer modeling studies showed their side chains to be surface exposed in the intact molecule. However, computer modeling also showed that none of the side chains of the polar residues in peptide 2 were sufficiently close to Q452 and Q453 to be able to contribute to a shared epitope. As peptide 2 could inhibit the binding of C1-inh autoantibodies to peptide 3 and vice versa, we conclude that an autoepitope also exists in peptide 2. Computer modeling and the use of substituted peptides suggested that the sequence LLVF (residues 446-449) in peptide 2 is structurally similar to the sequence QQPF (residues 452-455) in peptide 3. We therefore conclude that there are two potential epitopes in the intact C1-inh molecule that are capable of binding to C1-inh autoantibodies.

Peripheral blood CD4 but not CD8 t-lymphocytes in patients with exacerbation of asthma transcribe and translate messenger RNA encoding cytokines which prolong eosinophil survival in the context of a Th2-type pattern: effect of glucocorticoid therapy

T-lymphocyte (T-LC)-derived cytokines have been implicated in asthma pathogenesis. Activation of peripheral blood CD4 but not CD8 T-LC and a Th2-type pattern of elevated cytokine mRNA expression in BAL fluid T-LC have been observed in asthmatics, but the principal source (CD4 or CD8 T-LC) of these cytokines is unknown. Our objective was to measure expression of Th1- and Th2-type cytokine mRNA and spontaneous secretion of IL-3, IL-5, and GM-CSF by peripheral blood CD4 and CD8 T-LC from asthmatics before and after oral glucocorticoid therapy and non-asthmatic controls. We used in situ hybridization to detect mRNA expression in isolated CD4 and CD8 T-LC, and an in vitro eosinophil survival assay to detect secretion of IL-3, IL-5, and GM-CSF in T-LC culture supernatants. Comparing the asthmatics with the controls, elevated percentages of CD4 T-LC expressed mRNA encoding IL-5, IL-4, and GM-CSF (P < 0.02) but not IL-3, IL-2, or IFN-gamma. In CD8 T-LC, mRNA expression was generally low with no significant differences between the groups. In the asthmatics, the percentages of CD4 T-LC expressing IL-5 mRNA correlated with disease severity and the numbers of peripheral blood eosinophils (P < 0.01). Culture supernatants of asthmatic CD4 but not CD8 T-LC exhibited significantly higher (P = 0.0003) eosinophil survival-prolonging activity compared with controls, in which low activity was detected. Inhibition with anti-cytokine antibodies suggested that GM-CSF, and to a lesser extent IL-5 and IL-3, could account for this activity. After oral glucocorticoid therapy of the asthmatics, lung function improved and the percentages of CD4 T-LC expressing mRNA encoding IL-3, IL-5, and GM-CSF but not IL-2, IL-4, or IFN-gamma were reduced (P < 0.04). Secretion of eosinophil survival-prolonging activity by the CD4 T-LC was also reduced (P = 0.004). We conclude that peripheral blood CD4 but not CD8 T-LC from asthmatics express cytokine mRNA in a Th2-type pattern and show elevated secretion of cytokines prolonging eosinophil survival. Glucocorticoid therapy of asthmatics is associated with a reduction in the percentages of CD4 T-LC expressing IL-3, IL-5, and GM-CSF mRNA and secretion of the corresponding proteins.

Association of granulocyte-macrophage colony-stimulating factor with the crystalloid granules of human eosinophils

We have previously shown that normal-density human peripheral blood eosinophils transcribe and translate mRNA for granulocyte-macrophage colony-stimulating factor (GM-CSF) and that the intracellular distribution was granular as assessed by light microscopy immunocytochemistry. The present study was conducted to confirm this apparent association between GM-CSF and the crystalloid granule using a subcellular fractionation method for human eosinophils and immunogold electron microscopy (EM). Highly purified (> 99%, by negative selection using anti-CD16 immunomagnetic microbeads) human peripheral blood eosinophils were obtained from four asthmatic subjects (not taking systemic medication), homogenized and density fractionated (5 x 10(7) cells/subject) on linear Nycodenz gradients. Twenty-four fractions were collected from each cell preparation and analyzed for marker enzyme activities as well as total protein. Dot blot analysis with specific monoclonal antibodies (MoAbs) was used to detect the eosinophil granule proteins major basic protein (MBP) and eosinophil cationic protein (ECP). An anti-CD9 MoAb was used as an eosinophil plasma membrane marker. Lactate dehydrogenase (LDH) was used as a cytosolic marker. Immunoreactivity for GM-CSF was detected by a specific enzyme-linked immunosorbent assay using a polyclonal antihuman GM-CSF antibody and confirmed by dot blot. GM-CSF coeluted with the cellular fractions containing granule markers (MBP, ECP, eosinophil peroxidase, hexosaminidase, and arylsulphatase), but not those containing cytoplasm (LDH+) or membrane (CD9+) markers. EM examination of pooled fractions associated with the peak of GM-CSF immunoreactivity confirmed that they contained crystalloid and small granules, but not plasma membrane. In addition, quantification, using immunogold labeling with an anti/GM-CSF MoAb, indicated preferential localization of gold particles over the eosinophil granule cores of intact cells. Thus, our results indicate that GM-CSF resides as a granule-associated, stored mediator in unstimulated human eosinophils.

Antidiuretic hormone levels and polyuria in spinal cord injury. A preliminary report

Chronic cervical spinal cord injury is characterized by defects in sodium and water homeostasis and defects of adaptive hormonal responses. The plasma osmolality is maintained in a relatively narrow range, the lower limit of which is determined by osmotic threshold for vasopressin release and the upper limit by the third threshold. Antidiuretic hormone as an important mediator of fluid and electrolyte balance was well investigated in able bodied children comparing children with normal voiding pattern and children with enuresis. The normal subjects were found to have higher plasma ADH at night, not detected in the group with enuresis. The findings were similar in elderly patients with increased diuresis at night, suggesting an important role of ADH in nocturnal decrease of urine output. Investigators studied the effect of rapid tilt on plasma ADH in tetraplegic compared with normal subjects, but there are no data available in the literature regarding ADH and its effects on water and electrolyte balance in healthy tetraplegic subjects with a normal lifestyle. We decided to undertake a pilot study to attempt to establish baseline ADH levels in this subject group, to better understand and manage tetraplegic patients with water and electrolyte dysregulation. Our preliminary data suggest that these individuals lack the normal diurnal variation of ADH, a phenomenon similar to that demonstrated in enuretic children and elderly, and furthermore appear to have generally depressed ADH levels.

Bullous pemphigoid following radiotherapy

We report the case of a 57-year-old woman who developed bullous pemphigoid 3 weeks after electron beam radiotherapy. The bullae were confined to the area of the radiation field and responded to topical clobetasol propionate 0.05% cream (Dermovate). This is the second case of bullous pemphigoid confined to an area of previous radiotherapy. Radiotherapy may be a rare trigger for the development of bullous pemphigoid.

Kinetics of cell infiltration and cytokine messenger RNA expression after intradermal challenge with allergen and tuberculin in the same atopic individuals

BACKGROUND

Previous studies, in which one time point was used, have shown that cells infiltrating skin biopsy specimens taken during allergen-induced late-phase responses (LPR) had a TH2-like (interleukin-4 [IL]-4 and IL-5 mRNA+) cytokine profile, whereas in delayed-type hypersensitivity (DTH) there was a predominant TH1-type pattern.

OBJECTIVE

The study was designed to examine the kinetics of accumulation of inflammatory cells and cells expressing mRNA for TH2- or TH1-type cytokines in LPR and DTH elicited simultaneously in the same subjects.

METHODS

Immunocytochemistry (alkaline phosphatase anti-alkaline phosphatase technique) and in situ hybridization were used to analyze skin biopsy specimens taken during allergen-induced LPR.

RESULTS

In LPR elevated numbers of CD3+ and CD4+ cells, eosinophils, neutrophils, and IL-4 and IL-5 mRNA+ cells were detected as early as 1 hour after allergen challenge, with a peak at 6 hours, which was maintained for up to 96 hours. A small but significant delayed increase in macrophages, CD8+ and CD25+ cells, and IL-2 and interferon-gamma mRNA+ cells was also observed, but only at the 48-hour and 96-hour time points. In contrast, in DTH the numbers of CD3+, CD4+, and mRNA+ cells for IL-2 and interferon-gamma were not elevated until 24 hours after challenge and peaked at 48 hours after injection. At 48 hours there was an additional small but significant increase in IL-4 and IL-5 mRNA+ cells. For both LPR and DTH the kinetics of the increases in inflammatory cells and cytokine mRNA-expressing cells paralleled the clinical response.

CONCLUSIONS

In LPR accumulation of T cells and granulocytes, together with cells expressing mRNA encoding for TH2-type cytokines, is relatively rapid (i.e., within 1 to 6 hours), whereas in DTH the T cell/macrophage infiltration and appearance of cells expressing TH1-type cytokines are not apparent until 24 to 48 hours. In LPR there is a TH1-type (or possibly TH0) component at 48 to 96 hours, and in DTH there is an additional TH2/TH0 response.

Photodynamic inactivation of free and cell-associated HIV-1 using the photosensitizer, benzoporphyrin derivative

The photosensitizer benzoporphyrin derivative monoacid ring A (BPD) has been investigated regarding its ability to destroy free and cell-associated human immunodeficiency virus type 1 (HIV-1) when activated by light. Experiments with free virus in tissue culture medium indicate that light-activated BPD was effective in rendering HIV uninfectious. Azidothymidine (AZT)-resistant strains of HIV appear equally susceptible to photodynamic inactivation under drug and light conditions that proved effective in inactivating AZT-sensitive strains of HIV. Experiments conducted on whole blood from individuals infected with HIV demonstrate that BPD and light treatment could significantly reduce cell-associated virus, under conditions that appear not to damage red blood cells. The amount of culturable virus from infected leukocytes surviving photodynamic treatment could be further reduced by the addition of AZT to the culture.

Interleukin 1 beta, hand and foot bone mineral content and the development of joint erosions in rheumatoid arthritis

OBJECTIVE

To assess the relationship between plasma levels of the cytokine interleukin-1 beta (IL-1 beta) and the progression of rheumatoid arthritis (RA).

METHODS

Two subgroups of patients, one with persistently raised ESR (>/= 50 mm/hour, n = 16, group A) and one with persistently low ESR (</= 28 mm/hour), n = 18, group I) were chosen to represent stable extremes of inflammatory activity from a prospective study of 106 patients with active RA studied over one year in a single centre. The change from baseline in hand, foot and calcaneal bone mineral content measured by single photon absorptiometry and radiographic score of joint damage was measured over 12 months, together with plasma IL-1 beta and erythrocyte sedimentation rate.

RESULTS

Significant progression of joint damage occurred in both subgroups over one year (p < 0.0001, paired t test) though progression was significantly less in the subgroup with low ESR (p < 0.05, ANOVA). Hand and foot bone mineral content decreased by almost 10% in the subgroup with raised ESR (p < 0.005, paired t test). Stepwise linear regression analysis revealed significant independent relationships between radiographic progression over one year and plasma IL-1 beta and ESR (multiple R 0.674, F = 11.64, p < 0.0002). No such relationships were observed for changes in bone mineral content parameters.

CONCLUSIONS

Plasma IL-1 beta levels correlate weakly with progression of joint damage though not with loss of peripheral bone density in RA. A significant reduction in peripheral bone mineral content occurs over one year in patients with active RA with persistently raised ESR.

Stereoselective epoxidation of 2,2-dimethyl-2H-1-benzopyran-6-carbonitrile

The chiral intermediate (3S,4R)-trans-3,4-dihydro-3,4-dihydroxy-2,2-dimethyl- 2H-1-benzopyran-6-carbonitrile [(+)-trans diol 3] was made by the stereoselective microbial epoxidation of 2,2-dimethyl-2H-1-benzopyran-6-carbonitrile 1. This compound is a potential intermediate for the total synthesis of potassium-channel openers. Several microbial cultures were found which catalyzed the transformation of 1 to the corresponding (3S,4S)-epoxide 2 and (+)-trans diol 3. The two best cultures, Corynebacterium sp. SC 13876 and Mortierella ramanniana SC 13840 gave reaction yields of 32 M% and 67.5 M% and optical purities of 88 and 96%, respectively, for (+)-trans diol 3. A single-stage process (fermentation-epoxidation) for the biotransformation of 1 was developed using Corynebacterium sp. SC 13876 and M. ramanniana SC 13840. In a 25-L fermentor, the (+)-trans diol 3 was obtained in 38.6 M% yield with an optical purity of 90% using Corynebacterium SC 13876. The reaction yield of 60.7 M% and optical purity of 92.5% were obtained for (+)-trans diol 3 using M. ramanniana SC 13840. A two-stage process for the preparation of (+)-trans diol 3 was also developed using a 3 L cell-suspension (10% w/v, wet cells) of M. ramanniana SC 13840. The reaction was carried out in a 5-L Bioflo fermentor. The concentration of substrate 1 was 2 g L-1 with glucose present at 10 g L-1. After 48 h, (+)-trans diol 3 was obtained in 76 M% yield with an optical purity of 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

Migraine and migrainous stroke: risk factors and prognosis

We compared epidemiologic and clinical data from 310 patients with migraine and 30 patients with acute migrainous stroke to identify factors predictive of migrainous stroke and assess the risk of future stroke in these two populations. We found no significant differences in gender ratio or in the frequency of smoking, estrogen use, hypertension, mitral valve prolapse, or family history of migraine between the two groups. A history of migraine with aura was significantly more common in the migrainous stroke group (24 of 30 [80%] versus 142 of 310 [46%]; p < 0.001), as was a history of prior stroke (nine of 30 [30%] versus four of 310 [1.3%]; p < 0.001). We followed 173 of the migraine patients for at least 1 year and a mean of 35.8 months, and no strokes occurred in this group. We followed 28 of the migrainous stroke patients for a mean of 25.3 months, and there were six recurrent strokes in that group, all again migraine-associated. Migrainous stroke is more common in individuals with aura than in those who are aura-free, but this association is of little value in attempting to distinguish patients destined for migrainous stroke from the migraine population at large. Patients with a history of migraine-associated stroke are at significantly increased risk for recurrent stroke.

Relationships among numbers of bronchoalveolar lavage cells expressing messenger ribonucleic acid for cytokines, asthma symptoms, and airway methacholine responsiveness in atopic asthma

BACKGROUND

We recently demonstrated that T lymphocytes in bronchoalveolar lavage (BAL) fluid from atopic asthmatic patients were activated and expressed increased cytokine messenger ribonucleic acid (mRNA) for "TH2-type" cytokines, particularly IL-4 and IL-5, when compared with those in normal control subjects. This pattern of cytokines may determine the nature of the cellular infiltrate in the bronchial mucosa in asthma and hence the bronchial hyperresponsive (BHR) and symptoms that characterize this condition.

METHODS

To examine the association between these cytokines and clinical measures of asthma severity we have extended our studies of BAL cells from subjects with atopic asthma. Numbers of BAL cells with positive in situ hybridization signals for IL-2, IL-3, IL-4, IL-5, granulocyte macrophage colony-stimulating factor (GM-CSF), and interferon-gamma were counted on cytocentrifuge preparations. Results were compared between patients with symptomatic (n = 19) and asymptomatic asthma (n = 10), and associations were sought with airway methacholine responsiveness, resting airway caliber, and asthma symptom scores.

RESULTS

There were increased proportions of cells positive for IL-3 (p < 0.05), IL-4 (p < 0.005), IL-5 (p < 0.005), and GM-CSF (p < 0.005) mRNA in BAL fluid from patients with symptomatic asthma when compared with that from subjects free of symptoms, but no difference between the groups in numbers of cells expressing IL-2 and interferon-gamma mRNA. There were significant associations among numbers of cells expressing mRNA for IL-4, IL-5, and GM-CSF, and airflow restriction, BHR, and Aas asthma score.

CONCLUSIONS

These findings support the hypothesis that cytokines contribute to airway events that determine asthma symptoms and BHR.

Photosensitizers as virucidal agents

The photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) has been studied regarding its ability to destroy enveloped viruses in blood and blood products when activated by light. Its maximum wavelength of absorption (690 nm) has proven useful in terms of activation of the photosensitizer in materials containing red blood cells. Experiments conducted on whole blood of patients infected with the human immunodeficiency virus (HIV) demonstrated that BPD-MA and light could effectively eliminate the virus when treated materials were placed in culture and tested for viral p24, but did not appear to damage blood cells or blood components. Since HIV is largely intracellular in infected individuals, these results were investigated further. We have shown, using flow cytometry, that in HIV-infected blood, BPD-MA and light appear to selectively destroy white cells that bear the interleukin 2 receptor and the DR antigen. These markers are prevalent on activated lymphocytes, and since HIV replicates only in CD4+ T cells which are activated, this finding provides an explanation for the selective killing of HIV.

Photodynamic inactivation of retrovirus by benzoporphyrin derivative: a feline leukemia virus model

The ability of a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA), and either broad-spectrum (400-1200 nm) or narrow-band (600-700 nm) red light to kill feline leukemia virus (FeLV) and FeLV-infected cat T cells (cell line 3201) was investigated in culture medium containing fetal calf serum and in blood from infected cats. A molecular clone of FeLV, 61E, is minimally pathogenic and productively infects 3201 cells while causing no change in rate of cell division, viability, or size. Active virus (either free or within infected cells) was quantified by using a limiting dilution assay that involved cocultivation of test samples with naive 3201 cells, after which either the polymerase chain reaction or a reverse transcriptase assay was used to detect the presence of virus. It was shown that 61E-infected T cells in culture were slightly more sensitive to photodynamic killing than were uninfected cells. Infected cells and free virus were eliminated from whole blood taken from infected cats by using 4 micrograms per mL of BPD-MA and 40 J per cm2 of red light. These results correlate well with previous results with BPD-MA and vesicular stomatitis virus in whole human blood and suggest that this photosensitizer is a promising agent for the elimination of retroviruses that are either free or located within infected cells in blood.

Isolation and EBV-transformation of a minor population of normal human tonsillar B cells bearing a cold agglutinin-associated idiotope

Human autoantibodies which bind to red blood cells and cause agglutination in the cold, collectively comprise the cold agglutinins: a subset of these antibodies with specificity for the Ii carbohydrate antigen on the red cell surface bears cross-reacting idiotypic determinants. A monoclonal antibody has been raised which specifically inhibits the cold agglutination reaction, and has been used to probe normal lymphoid cell populations for the presence of B cells expressing the same idiotope. Although such cells comprise only 1-2% of the lymphoid cells in the tonsil, it has been possible to isolate them in good yield and purity using the antibody and magnetic beads. Released cells were infected with the Epstein-Barr (EB) virus and an idiotope-bearing line established. The IgM secreted by the line was found to agglutinate red cells in the cold indicating that cold agglutinin-producing cells were among this idiotope-positive population. The immunophenotype of the line, and the agglutinating power of the secreted IgM, have been compared with a similarly immortalized idiotope-bearing line established from neoplastic B cells of a patient with frank cold agglutination disease.

The importance of minutes, contracts and agreements

Hardly a day passes in the office of the RACGP Services Division without an enquiry from a general practitioner about an employment contract. These contracts are as important as our health records but unfortunately are poorly attended to and often missing from the office files. A little attention can save a lot of anguish.