Plasma Immunoglobulin M Research Articles

B-1b Cells Have Unique Functional Traits Compared to B-1a Cells at Homeostasis and in Aged Hyperlipidemic Mice With Atherosclerosis.

Immunoglobulin M (IgM) to oxidation specific epitopes (OSE) are inversely associated with atherosclerosis in mice and humans. The B-1b subtype of B-1 cells secrete IgM to OSE, and unlike B-1a cells, are capable of long-lasting IgM memory. What attributes make B-1b cells different than B-1a cells is unknown. Our objectives were to determine how B-1b cells produce more IgM compared to B-1a cells at homeostatic condition and to see the differences in the B-1a and B-1b cell distribution and IgM CDR-H3 sequences in mice with advanced atherosclerosis. Here, in-vivo studies demonstrated greater migration to spleen, splenic production of IgM and plasma IgM levels in ApoE-/-Rag1-/- mice intraperitoneally injected with equal numbers of B-1b compared to B-1a cells. Bulk RNA seq analysis and flow cytometry of B-1a and B-1b cells identified CCR6 as a chemokine receptor more highly expressed on B-1b cells compared to B-1a. Knockout of CCR6 resulted in reduced B-1b cell migration to the spleen. Moreover, B-1b cell numbers were significantly higher in spleen of aged atherosclerotic ApoE-/- mice compared to young ApoE-/- mice. Single cell sequencing results of IgHM in B-1a and B-1b cells from peritoneal cavity and spleen of atherosclerotic aged ApoE-/- mice revealed significantly more N additions at the V-D and D-J junctions, greater diversity in V region usage and CDR-H3 sequences in B-1b compared to B-1a cells. In summary, B-1b cells demonstrated enhanced CCR6-mediated splenic migration, IgM production, and IgM repertoire diversification compared to B-1a cells. These findings suggest that potential strategies to selectively augment B-1b cell numbers and splenic trafficking could lead to increased and more diverse IgM targeting OSE to limit atherosclerosis.

Converting Prescriptions to 90-day Supply Increases Specialty Pharmacy Technician Efficiency

The mechanisms by which exposure to heparin initiates antibody responses in many, if not most, recipients are poorly understood. We recently demonstrated that antigenic platelet factor 4 (PF4)/heparin complexes activate complement in plasma and bind to B cells. Here, we describe how this process is initiated. We observed wide stable variation in complement activation when PF4/heparin was added to plasma of healthy donors, indicating a responder “phenotype” (high, intermediate, or low). Proteomic analysis of plasma from these healthy donors showed a strong correlation between complement activation and plasma immunoglobulin M (IgM) levels (r = 0.898; P < .005), but not other Ig isotypes. Complement activation response to PF4/heparin in plasma displaying the low donor phenotype was enhanced by adding pooled IgM from healthy donors, but not monoclonal IgM. Depletion of IgM from plasma abrogated C3c generation by PF4/heparin. The complement-activating features of IgM are likely mediated by nonimmune, or natural, IgM, as cord blood and a monoclonal polyreactive IgM generate C3c in the presence of PF4/heparin. IgM facilitates complement and antigen deposition on B cells in vitro and in patients receiving heparin. Anti-C1q antibody prevents IgM-mediated complement activation by PF4/heparin complexes, indicating classical pathway involvement. These studies demonstrate that variability in plasma IgM levels correlates with functional complement responses to PF4/heparin. Polyreactive IgM binds PF4/heparin, triggers activation of the classical complement pathway, and promotes antigen and complement deposition on B cells. These studies provide new insights into the evolution of the heparin-induced thrombocytopenia immune response and may provide a biomarker of risk.

Adenosine Deaminase Two and Immunoglobulin M Accurately Differentiate Adult Sneddon’s Syndrome of Unknown Cause

Background: The association that exists between livedo reticularis (LR) and stroke is known as Sneddon’s syndrome (SnS). The disorder is classified as primary SnS (PSnS), if the cause remains unknown and secondary SnS. The condition is rare and it occurs mainly sporadically. In 2014, 2 independent teams described a new genetic disorder with childhood-onset, which was called deficiency of adenosine deaminase 2 (DADA2), characterized by recurrent fevers and vascular pathologic features that included LR and stroke. All the patients carried recessively inherited mutations in cat eye syndrome chromosome region candidate 1 gene (CECR1), encoding the adenosine deaminase 2 (ADA2) protein. Genetic testing is the standard for the diagnosis of DADA2. However, the diagnostic accuracy of more affordable laboratorial analysis in CECR1-mutated individuals remains to be established. We aim to determine whether plasma ADA2 activity and serum immunoglobulin M (IgM) levels can distinguish (1) DADA2 from other adult patients within the SnS spectrum, and (2) healthy CECR1 heterozygous (HHZ) from healthy controls (HC). Methods: ADA2 activity in plasma and serum IgM concentrations was measured in adult patients within the SnS spectrum, healthy first-degree relatives and HC. Genetic results were used as the reference standard. The primary outcome measures were sensitivity and specificity derived from receiver operating curve analysis. Results: A total of 73 participants were included in the study: 26 patients with PSnS with no CECR1 mutation (PSnS), 6 bi-allelic (DADA2 patients) and 7 HHZ CECR1 mutations and 34 HC. Plasma ADA2 activity and serum IgM levels were significantly lower in DADA2 patients than in PSnS. With the use of the best indexes, plasma ADA2 activity differentiated PSnS from DADA2 with a sensitivity and specificity of 100.0% and HHZ from HC with a sensitivity of 97.1% and specificity of 85.7%. Serum IgM levels also differentiated PSnS from DADA2 with a sensitivity of 85.2% and specificity of 83.3%. Conclusion: Serum IgM levels might be used as a triage tool and plasma ADA2 activity performs perfectly as a diagnostic test for DADA2 in adult patients within the SnS spectrum. ADA2 activity in plasma also reliably distinguishes HHZ from HC.

Polyreactive IgM initiates complement activation by PF4/heparin complexes through the classical pathway

AbstractThe mechanisms by which exposure to heparin initiates antibody responses in many, if not most, recipients are poorly understood. We recently demonstrated that antigenic platelet factor 4 (PF4)/heparin complexes activate complement in plasma and bind to B cells. Here, we describe how this process is initiated. We observed wide stable variation in complement activation when PF4/heparin was added to plasma of healthy donors, indicating a responder “phenotype” (high, intermediate, or low). Proteomic analysis of plasma from these healthy donors showed a strong correlation between complement activation and plasma immunoglobulin M (IgM) levels (r = 0.898; P < .005), but not other Ig isotypes. Complement activation response to PF4/heparin in plasma displaying the low donor phenotype was enhanced by adding pooled IgM from healthy donors, but not monoclonal IgM. Depletion of IgM from plasma abrogated C3c generation by PF4/heparin. The complement-activating features of IgM are likely mediated by nonimmune, or natural, IgM, as cord blood and a monoclonal polyreactive IgM generate C3c in the presence of PF4/heparin. IgM facilitates complement and antigen deposition on B cells in vitro and in patients receiving heparin. Anti-C1q antibody prevents IgM-mediated complement activation by PF4/heparin complexes, indicating classical pathway involvement. These studies demonstrate that variability in plasma IgM levels correlates with functional complement responses to PF4/heparin. Polyreactive IgM binds PF4/heparin, triggers activation of the classical complement pathway, and promotes antigen and complement deposition on B cells. These studies provide new insights into the evolution of the heparin-induced thrombocytopenia immune response and may provide a biomarker of risk.

Effects of waterborne copper on oxidative stress and immune responses in red seabream, Pagrus major

Copper (Cu) plays an essential role in many enzymatic processes including cellular respiration. In this study, we investigated the oxidative stress and immunity of red seabream, Pagrus major, exposed to different concentrations of Cu2+ (10, 20, 30, and 40 μg/L) for 120 h. We measured the expressions of mRNA, activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), the levels of plasma hydrogen peroxide (H2O2) and lipid peroxide (LPO), and immune parameters lysozyme, immunoglobulin M (IgM), and melatonin. The mRNA expressions, activities of antioxidant enzymes, and the levels of plasma H2O2 and LPO were significantly higher after exposure to 30 and 40 μg/L of Cu2+ than after exposure to lower concentrations (0, 10, and 20 μg/L). However, the levels of plasma lysozyme, IgM, and melatonin were significantly lower after exposure to 30 and 40 μg/L of Cu2+. These results indicate that Cu2+ concentrations of 30 and 40 μg/L can induce an acute toxic oxidative stress and decrease the immune response in red seabream in aquarium conditions.

Anti-TIM-1 Monoclonal Antibody (RMT1-10) Attenuates Atherosclerosis By Expanding IgM-producing B1a Cells.

BackgroundPeritoneal B1a cells attenuate atherosclerosis by secreting natural polyclonal immunoglobulin M (IgM). Regulatory B cells expressing T‐cell immunoglobulin mucin domain‐1 (TIM‐1) expanded through TIM‐1 ligation by anti‐TIM‐1 monoclonal antibody (RMT1‐10) induces immune tolerance.Methods and ResultsWe examined the capacity of RMT1‐10 to expand peritoneal B1a cells to prevent atherosclerosis development and retard progression of established atherosclerosis. RMT1‐10 treatment selectively doubled peritoneal B1a cells, tripled TIM‐1+ B1a cells and increased TIM‐1+IgM+interleukin (IL)‐10+ by 3‐fold and TIM‐1+IgM+IL‐10− B1a cells by 2.5‐fold. Similar expansion of B1a B cells was observed in spleens. These effects reduced atherosclerotic lesion size, increased plasma IgM and lesion IgM deposits, and decreased oxidatively modified low‐density lipoproteins in lesions. Lesion CD4+ and CD8+ T cells, macrophages and monocyte chemoattractant protein‐1, vascular cell adhesion molecule‐1, expression of proinflammatory cytokines monocyte chemoattractant protein‐1, vascular cell adhesion molecule‐1, IL1β, apoptotic cell numbers and necrotic cores were also reduced. RMT1‐10 treatment failed to expand peritoneal B1a cells and reduce atherosclerosis after splenectomy that reduces B1a cells, indicating that these effects are B1a cell‐dependent. Apolipoprotein E‐KO mice fed a high‐fat diet for 6 weeks before treatment with RMT1‐10 also increased TIM‐1+IgM+ IL‐10+ and TIM‐1+IgM+ IL‐10− B1a cells and IgM levels and attenuated progression of established atherosclerosis.Conclusions RMT1‐10 treatment attenuates atherosclerosis development and progression by selectively expanding IgM producing atheroprotective B1a cells. Antibody‐based in vivo expansion of B1a cells could be an attractive approach for treating atherosclerosis.

Lymphocyte-specific protein tyrosine kinase (LCK) is involved in the aryl hydrocarbon receptor (AHR)-mediated impairment of Immunoglobulin secretion in human primary B cells

Abstract AHR activation by the high affinity ligand, TCDD, is widely established to suppress the immunoglobulin M (IgM) response in virtually every animal species tested, and extensively investigated in various mouse models. In mice, activation of AHR is known to impair B cell to plasma cell differentiation and IgM synthesis. In contrast to mouse B cells, activation of AHR in human primary B cells impairs immunoglobulin secretion in the absence of suppressing IgM synthesis. In recent studies, we have identified the putative involvement of LCK in impaired immunoglobulin secretion by human B cells. LCK is a well-characterized tyrosine kinase that phosphorylates known critical signaling proteins involved in vesicular secretion by T cells. Specifically, phosphorylation of tyrosine residue 505 inhibits the activity of LCK. By contrast, little is known concerning the role of LCK in human primary B cells. For the first time, our studies show that activation of the AHR by TCDD upregulates LCK protein expression, which then leads to an impairment of IgM secretion. Treatment with a LCK specific inhibitor restores IgM secretion by human primary B cells. Additionally, the presence of AHR antagonist reverses the AHR-mediated increase of LCK and the impairment of IgM secretion. We also observe a significant increase in phosphorylation of Tyr-505 LCK with TCDD treatment, indicating that AHR activation increases the level of inhibitory LCK. Taken together, our studies revealed a novel and species-dependent mechanism involving the AHR-mediated impairment of IgM secretion and an increase in total as well as inhibitory LCK in human but not mouse primary B cells.

Effects of dietary arginine on antioxidant status and immunity involved in AMPK-NO signaling pathway in juvenile blunt snout bream

The present study assessed the effects of dietary arginine on antioxidant status and immunity involved in AMPK-NO signaling pathway in juvenile blunt snout bream. Fish were fed six practical diets with graded arginine levels ranging from 0.87% to 2.70% for 8 weeks. The results showed that compared with the control group (0.87% dietary arginine level), significantly higher mRNA levels of adenosine monophosphate activated protein kinase (AMPK) and nitric oxide synthetase (NOS), activities of total nitric oxide synthetase (T-NOS) and nitric oxide synthetase (iNOS), and plasma nitric oxide (NO) contents were observed in fish fed with 1.62%–2.70% dietary arginine levels. Significantly higher levels of NOS and iNOS were observed in fish fed with 1.62%–2.70% dietary arginine levels in enzyme-linked immune sorbent assay. At dietary arginine levels of 1.22%–2.70%, the mRNA levels of iNOS were significantly improved. Dietary arginine also significantly influenced plasma interleukin 8 (IL-8) and tumour necrosis factor-α (TNF-α) contents. Furthermore, dietary arginine significantly affected the activity and mRNA level of glutathione peroxidase (GPx), the mRNA levels of pro-inflammatory factor including IL-8 and TNF-α and plasma malondialdehyde (MDA) content. However, total superoxide dismutase (T-SOD) activity, plasma complement component 3 (C3) content, plasma immunoglobulin M (IgM) content, plasma interleukin 1β (IL-1β) content and the mRNA levels of copperzinc superoxide dismutase (Cu/Zn-SOD), manganese superoxide dismutase (Mn-SOD) and IL-1β were not significantly affected by dietary arginine. After Aeromonas hydrophila challenge, the death rate was significantly lowered in fish fed with 1.62%–1.96% dietary arginine levels. Furthermore, the mRNA levels of AMPK, NOS and iNOS, plasma NO content and the activities of T-NOS and iNOS showed an upward trend with increasing dietary arginine levels. Significantly higher levels of NOS and iNOS were observed in fish fed with 1.62%–2.70% dietary arginine levels in enzyme-linked immune sorbent assay. At dietary arginine levels of 1.96%–2.31%, T-SOD activities were significantly improved. Significantly higher GPx activities were observed in fish fed with 1.22%–2.70% dietary arginine levels. At dietary arginine levels of 1.22%–2.31%, the plasma TNF-α and IL-8 contents were significantly decreased. Significantly lower plasma IL-1β contents were observed in fish fed 1.62%–1.96% dietary arginine levels. Dietary arginine significantly influenced the mRNA levels of antioxidant and pro-inflammatory genes including Cu/Zn-SOD, Mn-SOD, GPx, IL-8, TNF-α and IL-1β. Significantly higher plasma C3 contents and significantly lower plasma MDA contents were observed in fish fed with 1.62%–1.96% arginine levels. Furthermore, plasma IgM contents were significantly improved at dietary arginine levels of 1.62%–2.31%. However, high dietary arginine group (2.70%) significantly improved the mRNA levels of pro-inflammatory genes including IL-8, TNF-α and IL-1β and plasma MDA, IL-8, TNF-α and IL-1β contents as compared with optimal dietary arginine levels (1.62% and 1.96%). The present results indicate that optimal arginine level (1.62% and 1.96%) could improve antioxidant capacity, immune response and weaken tissues inflammatory involved in arginine-AMPK-NO signaling pathway, while high arginine level resulted in excessive NO production, leading to increase oxidative stress damage and inflammatory response in juvenile blunt snout bream.

Effects of melatonin and green-wavelength LED light on the physiological stress and immunity of goldfish, Carassius auratus, exposed to high water temperature.

This study investigated the effects of increasing water temperature (22-30°C) on the physiological stress response and immunity of goldfish, Carassius auratus, and the ability of green light-emitting diode (LED) irradiation or melatonin injections to mitigate this temperature-induced stress. To evaluate the effects of either green-wavelength LED light or melatonin on stress in goldfish, we measured plasma triiodothyronine (T3), thyroxine (T4), and thyroid hormone receptor (TR) mRNA expression; plasma cortisol and glucose; and immunoglobulin M (IgM) and lysozyme mRNA expression. The thyroid hormone activities, TR mRNA expression, and plasma cortisol and glucose were higher in goldfish exposed to high-temperature water, but were lower after exposure to melatonin or green-wavelength LED light. Lysozyme mRNA expression and plasma IgM activity and protein expression were lower after exposure to high water temperatures and higher after melatonin or green-wavelength LED light treatments. Therefore, high water temperature induced stress and decreased immunity; however, green-wavelength LED light and melatonin treatments mitigated the effects of stress and enhanced immunity. The benefits of melatonin decreased with time, whereas those of green-wavelength LED treatment did not.

Immunoglobulin M, C-Reactive Protein and Complement Activation in Rat Hepatic Ischemia-Reperfusion Injury

Background: Ischemia-reperfusion (I/R) models have shown that C-reactive protein (CRP) and immunoglobulin M (IgM) are involved in complement activation. Binding of CRP and IgM to damaged cell membranes initiates complement activation and aggravates I/R injury in various organs. However, the time course of CRP- and IgM-mediated complement activation and the relation to hepatocellular injury and inflammation in liver I/R are unknown. Aim: To evaluate the time course of IgM- and CRP-related complement activation and the relation to hepatocellular injury and inflammation in a hepatic I/R rat model. Methods: Male Wistar rats were allocated to (1) five groups of animals exposed to 60 min of partial ischemia (70%) induced via clamping of the left segmental portal triad, followed by 0, 3, 6, 12 or 24 h of reperfusion (n = 6 in each group); (2) five groups of sham-operated animals with corresponding reperfusion times (n = 5), and (3) a control group sacrificed before ischemia (n = 5). Hepatocellular injury, inflammatory response, rat plasma CRP and IgM levels and immunohistochemical depositions of CRP, IgM and C3 were assessed for each group. Results: Histopathological injury scores of hematoxylin and eosin sections of ischemic liver lobes demonstrated increasing values throughout the reperfusion time with a peak at 12 h. Plasma aminotransferases (alanine aminotransferase and aspartate aminotransferase) significantly increased after 3 h of reperfusion, peaking at 6 h (3,100 ± 800 U/l; p < 0.05). Hepatic neutrophil influx significantly increased from 3 to 6 h of reperfusion (p < 0.05) and demonstrated the highest value at 12 h (1.1 ± 0.2 U/mg of protein). Plasma IL-6 levels in the ischemia groups showed peak values after 6 h of reperfusion, decreasing significantly thereafter (p < 0.05). Plasma CRP values reached highest levels after 3 h of reperfusion (mean 91 ± 5% of control pool), decreasing significantly thereafter. Rat IgM concentrations in plasma did not significantly change throughout the reperfusion time. Immunohistochemical depositions of IgM, CRP and C3 in ischemic lobes demonstrated a similar pattern in time, reaching maximum values at 12 h of reperfusion. The percentages of depositions of CRP and IgM were significantly correlated [r(S) = 0.569; p < 0.001; Spearman test]. The time course of C3 and CRP depositions throughout reperfusion and C3 and IgM staining were significantly similar [r(S) = 0.797 and r(S) = 0.656, respectively; p < 0.0001; ANOVA]. Conclusions: CRP and IgM depositions demonstrate a parallel time course throughout the reperfusion to hepatocellular damage, inflammatory response and activated complement deposition in this rat hepatic I/R model. Furthermore, the time course of CRP and IgM depositions was significantly similar to that of activated complement depositions.

Effect of Plasmapheresis on Hyperviscosity-Related Retinopathy and Retinal Hemodynamics in Patients with Waldenström’s Macroglobulinemia

Waldenström's macroglobulinemia (WM) is characterized by an overproduction of immunoglobulin M (IgM), which can lead to a hyperviscosity syndrome (HVS) and HVS-related retinopathy. Plasmapheresis is known to reduce serum viscosity (SV) and IgM levels. The purpose of this study was to investigate the effects of plasmapheresis on HVS-related retinopathy and retinal hemodynamic parameters in patients with WM. Nine patients with HVS due to WM were studied. SV and plasma IgM levels were measured before and after plasmapheresis treatment. The patients were evaluated for HVS-related retinopathy, and hemodynamic changes in a major temporal retinal vein by laser Doppler, before and after plasmapheresis. Plasmapheresis resulted in significant reductions in serum IgM (46.5% +/- 18.0%, mean +/- SD; P = 0.0009) and SV (44.7% +/- 17.3%, P = 0.002). HVS-related retinopathy improved in all patients after plasmapheresis. After treatment, the venous diameter decreased in each patient by an average of 15.3% +/- 5.8% (P = 0.0001). A significant (P = 0.0004) 55.2% +/- 22.5% increase in retinal venous blood speed accompanied the decreases in diameter. There was no significant change in the retinal blood flow rate after treatment. The percentage decreases in SV in the patients were significantly correlated with the percentage decreases in venous blood column diameter (P = 0.031, R(2) = 0.51). HVS triggers a distinctive retinopathy with a central retinal vein occlusion (CRVO)-like appearance. However, the retinal blood flow is not decreased as in CRVO, but remains at normal levels. Plasmapheresis is effective in reversing HVS-related retinopathy and in reducing abnormal venous dilatation.

Impact of different environmental factors on the circulating immunoglobulin levels in the Nile tilapia, Oreochromis niloticus

Immunoglobulin M (IgM) in teleost fishes is the only component of the specific humoral defense system that is affected by environmental factors. In the present study, we examined the effect of various environmental factors (water temperature, salinity, pH and suspended solids) on the plasma IgM in the Nile tilapia, Oreochromis niloticus. For all treatments, fish were acclimatized in particular environmental conditions for 2 or 4 weeks. For fish reared at 18.4, 23 and 28 °C, the circulating IgM concentration increased with increased water temperature for 2 weeks. Rearing the fish at 33 °C resulted in a decrease in IgM concentration, suggesting that the fish possess an appropriate thermal range for production of immune substances. Plasma level of IgM increased significantly with salinity at 12 and 24 parts per thousand (ppt). On the other hand, plasma IgM concentration did not change by exposing the fish to acidification (pH 4.0) and suspended solids (20, 200, and 2000 mg/l). These results suggest that the specific immune system of tilapia changes by certain factors in aquatic environment.

Gender‐ and season‐dependent relationships between testosterone, oestradiol and immune functions in wild roach

Plasma testosterone and 17β‐oestradiol concentrations, differential leukocyte counts and proportion of dead Rhipidocotyle campanula gill parasites (parasite resistance) were determined five times during a year in two populations of roach Rutilus rutilus and analysed for seasonal and gender differences. In addition to the above immune variables, plasma Immunoglobulin M (IgM) concentration, chemiluminescence and migration differential of head kidney phagocytes, size of the spleen, haematocrit and total leukocyte count were correlated with sex hormones for each population, sampling time and sex separately, using condition factor as a partial correlate. There were no clear gender differences in the determined immune variables. Both testosterone and oestradiol concentrations were lowest after the spawning in June. Oestradiol was higher in females than in males, but testosterone was present in equal concentrations in both sexes. Statistically significant correlations between sex hormones and immune variables were rare and mainly without any patterns with respect to population, sex or sampling date. The meta‐analysis on individual correlations, however, revealed a positive relationship of plasma testosterone concentration to chemiluminescence of head kidney phagocytes, plasma IgM concentration and the proportion of dead R. campanula to all R. campanula on the gills. In the meta‐analysis, the concentration of oestradiol was not found to correlate with any of the studied immune variables.

The effect of dietary phosphorus deficiency on the immune responses of European whitefish ( Coregonus lavaretus L.)

Low phosphorous (P) feeds in aquaculture are recommended to reduce eutrophication of water systems. However, the feed should be adequate for normal growth and intact immune defence. Influence of low dietary P supply on non-specific and specific immune defence of European whitefish ( Coregonus lavaretus) was studied in two trials. For Trial 1, a semi-purified, low-P diet was formulated and supplied with 0, 2.5, 5.0, 7.5, or 10.0 g P kg −1to obtain a P gradient of 4.4–14.9 g kg −1diet. Diets were fed to four replicate groups of fingerling whitefish for 42 days in a flow-through, freshwater system maintained at 15 °C. Fish fed with the P-unsupplemented diet had significantly lower plasma immunoglobulin M (IgM) levels than fish fed with the P-fortified diets (means 2.53 vs. 3.19 mg ml −1; P=0.047). Plasma lysozyme activity did not differ between fish fed with the P-unsupplemented diet and fish fed with the P-fortified diets (means 21.8 vs. 25.5 U ml −1; P=0.107). For Trial 2, fish were acclimated for 49 days by feeding the lowest or highest dietary P contents, and thereafter immunised with a single intraperitoneal injection of a novel antigen, bovine gamma globulin (BGG). A clear antibody response against BGG was elicited but the antibody levels did not differ between fish fed low-P or high-P contents. Similar to Trial 1, plasma IgM was lower in fish fed low-P diets, and low-P diet did not influence plasma lysozyme activity. In both trials the growth of fish, having received low-P diet, was significantly lowered. It is concluded that P deficiency has only minor effects on the immune parameters in whitefish, and the practical aquafeed with P contents sufficient for normal growth does not compromise immune functions of this species.

Cold-Stress Induced the Modulation of Catecholamines, Cortisol, Immunoglobulin M, and Leukocyte Phagocytosis in Tilapia

The concentrations of norepinephrine in hypothalamus and norepinephrine and epinephrine in head kidney were significantly decreased in treated tilapia (Oreochromis aureus) during the time course of cold exposure (12°) as compared to the control (25°). The elevation of norepinephrine and epinephrine in plasma was detected earlier than that of cortisol in cold-treated tilapia. Phagocytic activity of leukocytes and the levels of plasma immunoglobulin M (IgM) were depressed in cold-treated tilapia as compared to the control group. Handling stress in the control (25°) also resulted in increased plasma cortisol and decreased plasma IgM levels but not phagocytic activity. In vitro cortisol suppressed leukocyte phagocytosis in a dose (10−12 to 10−4 M)-dependent manner. Adrenergic agonist (phenylephrine and isoproterenol) had a significant suppression of phagocytosis only at the highest dose (10−4 M). No effect on phagocytosis was detected in the treatment with norepinephrine and epinephrine. A combination of cortisol and isoproterenol (0.1 mM) had an additive effect in the suppression of phagocytosis. It is concluded that the cold stress modulated the changes of catecholamines and cortisol and further depressed phagocytic activity and antibody levels in tilapia. Cortisol could play a main and important role in the down-regulation of phagocytic activity. Adrenergic agonists also could interact with cortisol to further suppress immunity in tilapia.

CORD BLOOD LYMPHOCYTE FUNCTIONS IN NEWBORNS FROM A REMOTE MARITIME POPULATION EXPOSED TO ORGANOCHLORINES AND METHYLMERCURY

The consumption of fish and sea mammals can be an important source of exposure to organochlorine compounds (OCs) and heavy metals in populations relying on seafood for subsistence. Exposure to these substances, especially during the prenatal period, has been shown to induce immunotoxic effects in mammals. Immunological status was assessed in 48 newborns from a remote maritime population living on the Lower and Mid North Shore of the St. Lawrence River (subsistence fishing group) and 60 newborns from the coastal urban center of Sept-Îles (reference group). Women were recruited upon arrival at Sept-Îles regional hospital to give birth. Cord blood samples were collected for organochlorine and heavy metal analyses and to isolate lymphocytes for immunological assays (proportions and functional responses of the main cellular subsets T, B, and NK (natural killer) cells. Concentrations of polychlorinated biphenyls (PCBs) and mercury were respectively three-and twofold higher, significantly greater, in the subsistence fishing group than in the reference group. Compared to the reference group, the subsistence fishing group showed significant decreases in the proportion of the naive helper T-cell subset CD4 + CD45RA + , T-cell proliferation following an in vitro mitogenic stimulation, and plasma immunoglobulin M (IgM) level, while plasma IgG level was increased. NK cytolytic activities were similar in both groups. The proportion of CD4 + CD45RA + cells was inversely correlated to mercury and PCBs, while T-cell clonal expansion was negatively associated with PCBs and p,p '-DDE. Mercury was inversely correlated to plasma IgM. Data show that subtle functional alterations of the developing human immune system may result from in utero exposure to OCs and mercury. Epidemiological studies are needed to determine the relevance of these alterations in predicting detrimental health effects in the developing child.

Ultraviolet B irradiation modulates the immune system of fish (Rutilus rutilus, Cyprinidae). Part III: Lymphocytes.

The effects of short-term exposure to ultraviolet B (UVB) radiation on lymphocyte-related parameters were studied under controlled laboratory conditions using roach (Rutilus rutilus), a cyprinid teleost, as the model fish. In vitro lymphoproliferative responses stimulated with a T-cell-specific mitogen, concanavalin A (ConA), or a B-cell-specific activator, lipopolysaccharide (LPS), were decreased in exposed fish. Also nonstimulated proliferation was lower than in unexposed fish. ConA-activated responses returned to normal levels within 7 days after exposure, but LPS-activated responses were reduced throughout the 14 day follow-up. The capability of UVB-exposed fish to produce an antibody response was studied by intraperitoneal immunization with bovine gamma-globulin (BGG). The concentration of anti-BGG antibodies in plasma as well as the number of anti-BGG-specific antibody-secreting cells in the spleen or blood were not decreased in fish exposed either to a single dose of UVB prior to immunization, or to single dose of UVB prior to immunization followed by three additional doses after immunization. Immunoglobulin M (IgM) production, when assayed as plasma IgM level or as the number of IgM-secreting cells in the spleen or blood, was not suppressed after exposure to UVB irradiation. These results indicate that a single dose of UVB or short-term exposure to UVB irradiation has no negative effects on IgM production or reactivity against antigen administered via the intraperitoneal route. However, the suppression of in vitro lymphoproliferative responses suggest that exposure to UVB has the potential to interfere with lymphocyte-related functions in fish.

Effects of Prolactin and Growth Hormone on Plasma Immunoglobulin M Levels of Hypophysectomized Rainbow Trout, Oncorhynchus mykiss

Immunoglobulin M (IgM) is a major component of the humoral immune system of teleosts. This study examines the effects of hypophysectomy and subsequent replacement with prolactin (PRL) or growth hormone (GH) upon the plasma IgM levels of the rainbow trout (Oncorhynchus mykiss). Plasma IgM levels of the hypophysectomized fish were decreased to 30% of those in sham-operated fish 1 or 4 weeks after operation. Implantation of a cholesterol pellet containing salmon PRL or GH restored plasma IgM levels of the hypophysectomized fish, suggesting important roles for PRL and GH in the regulation of circulating IgM level in trout.

Changes in Immunoglobulin Producing Cells in Response to Gonadal Maturation in Rainbow Trout

Changes in the number of immunoglobulin producing cells (IPC), immunoglobulin M (IgM) levels and leukocyte counts were investigated in rainbow trout reared under constant water temperature with special reference to gonadal maturation. During the spawning season, leucocytopenia, decreased number of antibody producing cells and low plasma IgM levels were observed. These reductions were apparently correlated with elevations in plasma cortisol (F), testosterone (T) and estradiol-17β in female and F, T and 11-ketotestosterone in males. In addition, decreased number of antibody producing cells in the skin lymphocytes and low mucus IgM levels were observed during the spawning season. These results suggest that endocrine changes related to gonadal maturation cause overall suppression of immune functions.

Age-related changes in plasma IgM level after SRBC-stimulation in the rat

The aim of our investigation was to detect age-related changes in the immune system and immune response of the rat in order to establish a system of biological markers of aging in the immune system. Our results demonstrate significant changes with increasing age in the immune system of Sprague-Dawley rats. Immunoglobulin M (IgM) plasma concentrations showed significant age-related differences after immunization with sheep red blood cells (SRBC). An increase in IgM plasma concentration after exogenous stimulation was found only in young and adult animals but not in old ones. Furthermore, we were able to demonstrate an age-dependent decrease in the peripheral blood lymphocyte count (PBL) and the W3/13-cell count, whereas plasma IgM concentration and polymorphonuclear cell count (PMNC) increased with age in the animals between 12 and 32 months of age. Because of these data, we suggest that the observed decline in humoral immune response with age indicates a decline in cell-mediated immunity.