Heterophil Concentrations Research Articles

Leukocyte Concentrations Are Isometric in Reptiles Unlike in Endotherms.

AbstractHow do large and small reptiles defend against infections, given the consequences of body mass for physiology and disease transmission? Functionally equivalent mammalian and avian granulocytes increased disproportionately with body mass (i.e., scaled hypermetrically), such that large organisms had higher concentrations than expected by a prediction of proportional protection across sizes. However, as these scaling relationships were derived from endothermic animals, they do not necessarily inform the scaling of leukocyte concentration for ectothermic reptiles that have a different physiology and evolutionary history. Here, we asked whether and how lymphocyte and heterophil concentrations relate to body mass among more than 120 reptile species. We compared these relationships to those found in birds and mammals and to existing scaling frameworks (i.e., protecton, complexity, rate of metabolism, or safety factor hypotheses). Both lymphocyte and heterophil concentrations scaled almost isometrically among reptiles. In contrast, functionally equivalent granulocytes scaled hypermetrically and lymphocytes scaled isometrically in birds and mammals. Life history traits were also poor predictors of variation in reptilian heterophil and lymphocyte concentrations. Our results provide insight into differences in immune protection in birds and mammals relative to that in reptiles through a comparative lens. The shape of scaling relationships differs, which should be considered when modeling disease dynamics among these groups.

Leucocytes are Mass‐Invariant in Reptiles Unlike in Endotherms

How do large and small animals defend against parasite challenges given the consequences of body mass on physiology and disease transmission? Functionally equivalent mammalian and avian granulocytes increased disproportionately with mass (i.e., hypermetrically), such that large organisms have higher concentrations than expected by mass alone. However, how ectothermic leucocyte concentrations scale is understudied. We hypothesized that differences exist in the scaling of leucocyte concentrations between endotherms and ectotherms as these groups have substantial differences in their physiology and immunology. Analysis was conducted using MCMCglmm, phylogenetically informed models to determine which existing scaling hypothesis best predicted relationships between mass and lymphocyte and heterophil concentrations among >120 species of reptiles and compared our results with those from birds and mammals. We also compared body mass and life history as a predictor of variation in immune cell concentrations. Reptilian lymphocyte concentrations scaled close to isometrically (i.e., mass‐invariant; phylogenetic MCMCglmm: b(mean, 95% CI) = ‐0.040, [‐0.072, ‐0.007]), and the slope was indistinguishable from the slope found for mammals and birds. In contrast, reptilian heterophil concentrations scaled isometrically (b =0.006, [‐0.028, 0.040]), whereas functionally equivalent mammalian and avian granulocytes scaled hypermetrically. Although reptilian leucocytes were mass‐invariant, the slope was greater than predicted if metabolic rate serves as a pace marker for immune defenses, suggesting that large organisms have greater protection than expected by the Rate of Metabolism Hypothesis. Life history was also a poor predictor of variation in reptilian heterophil and lymphocyte concentrations. Our results provide novel insight into large scale patterns of immune defenses of endothermic and ectothermic vertebrates and have direct implications for modeling the evolution of immune defenses and identifying parasite reservoirs.

Changes in haematological parameters in hens under short-term exposure to adverse environmental factors

Short-term exposure to adverse factors is a common phenomenon in industrial egg production. An urgent problem is to understand the impact of environmental changes on poultry use. A comparative analysis of changes in haematological parameters in hens under short-term exposure to adverse environmental factors of different natures was performed. For this purpose, a control and 3 experimental groups of hens were established in a modern complex for the production of food eggs. Within 24 hours, the hens of the 2nd group were deprived of fodder, the 3rd group – of light, and the 4th group – were kept in significant overcrowding. The smallest changes in the blood system of hens were observed under the influence of the factor of lack of fodder, namely an increase, within the physiological standard, in the content of leukocytes and erythrocyte sedimentation rate, a decrease in haemoglobin concentration, hematocrit, erythrocytes, platelets, and a violation of the ratio of different forms of leukocytes – an increase in the concentration of heterophils (3.3%>normal) against a decrease in the concentration of monocytes (1.6%<normal), lymphocytes and basophils. Therewith, under the influence of the factor of the absence of light, a higher content of leukocytes in the blood by 10.6%, a lower concentration of haemoglobin by 22.4%, hematocrit – by 4.2%, platelets – by 9.8%, and a higher erythrocyte sedimentation rate by 9.8%, a higher concentration of heterophils by 5.9% and a lower concentration of lymphocytes – by 4.6% were identified compared to the factor of the absence of fodder. The most significant changes in the blood system were noted under the influence of the factor of significant over-consolidation of hens, namely, a higher content of leukocytes in the blood by 17.1 and 5.9%, a lower concentration of haemoglobin by 29.6 and 9.2%, hematocrit – by 5.9 and 1.7%, erythrocytes – by 10.3%, platelets – by 35.8 and 28.8%, and higher erythrocyte sedimentation rate by 4.9%, a higher concentration of heterophils by 11.3 and 5.4 % and lower concentration of monocytes by 0.8 and 0.4%, lymphocytes by 9.4 and 4.8% and eosinophils by 0.7% compared to the factor of lack of fodder and lack of light, respectively. Thus, in production conditions, it is necessary to avoid the over-compaction of poultry, as this factor has the greatest adverse effect

Seasonal variation in sex-specific immunity in wild birds

Whilst the immune system often varies seasonally and exhibits differences between males and females, the general patterns in seasonality and sex differences across taxa have remained controversial. Birds are excellent model organisms to assess these patterns, because the immune system of many species is well characterised. We conducted a meta-analysis using 41 wild bird species from 24 avian families to investigate sex differences and seasonal (breeding/non-breeding) variations in immune status, including white blood cell counts, phytohaemagglutinin (PHA) test, bacteria-killing ability (BKA), haemolysis and haemagglutination assays. We found male-biased macrophage concentration, BKA and haemolysis titers, but only during the breeding season. Sex-specific heterophil concentrations, heterophil/lymphocyte ratios and PHA responses differed between breeding and non-breeding, suggesting larger changes in males than in females. Importantly, sex differences in immune status are stronger during the breeding period than during the non-breeding period. Taken together, our study suggests that both seasonal variation and sex differences in immune system are common in birds, although their associations are more complex than previously thought.

The impacts of body mass on immune cell concentrations in birds

Body mass affects many biological traits, but its impacts on immune defences are fairly unknown. Recent research on mammals found that neutrophil concentrations disproportionately increased (scaled hypermetrically) with body mass, a result not predicted by any existing theory. Although the scaling relationship for mammals might predict how leucocyte concentrations scale with body mass in other vertebrates, vertebrate classes are distinct in many ways that might affect their current and historic interactions with parasites and hence the evolution of their immune systems. Subsequently, here, we asked which existing scaling hypothesis best-predicts relationships between body mass and lymphocyte, eosinophil and heterophil concentrations-the avian functional equivalent of neutrophils-among more than 100 species of birds. We then examined the predictive power of body mass relative to life-history variation, as extensive literature indicates that the timing of key life events has influenced immune system variation among species. Finally, we ask whether avian scaling patterns differ from the patterns we observed in mammals. We found that an intercept-only model best explained lymphocyte and eosinophil concentrations among birds, indicating that the concentrations of these cell types were both independent of body mass. For heterophils, however, body mass explained 31% of the variation in concentrations among species, much more than life-history variation (4%). As with mammalian neutrophils, avian heterophils scaled hypermetrically (b = 0.19 ± 0.05), but more steeply than mammals (approx. 1.5 ×; 0.11 ± 0.03). As such, we discuss why birds might require more broadly protective cells compared to mammals of the same body size. Overall, body mass appears to have strong influences on the architecture of immune systems.

Phytohaemagglutinin injection has a long‐lasting effect on immune cells

Measurement of phytohaemagglutinin (PHA)‐induced skin swelling is the most popular assay of immune function in avian studies. The mechanisms causing swelling have been relatively well studied; however, very little is known about the potential long term physiological effects of PHA. Here we show that injection of PHA into patagium of captive greenfinches Carduelis chloris increases the concentration of heterophils (phagocytic cells of the innate immune response) in the peripheral blood for at least 30 days. Such long‐term consequences should be taken into account when using PHA skin test in studies monitoring changes in individual physiological condition and/or immune status.

Haematological indicators of inflammation exhibited by Australian Falconiformes

Numerous studies have reported some haematological characteristics of diurnal raptors; however, few of these have characterised the haematological response to disease. We investigated the haematological characteristics, exhibited in response to a range of injuries and naturally occurring inflammatory disease, of seven birds from six species of Falconiformes. A spectrum of leukocyte responses was observed. Some form of morphological atypia was evident in the heterophils of all birds and was the most reliable indicator of inflammation. The concentration of leukocytes varied between each case, with the least concentration of heterophils observed to be 0.18 × 109/l and the greatest concentration of heterophils observed to be 6.00 × 109/l. This study illustrates the heterogeneous haematological response exhibited by Falconiformes to different inflammatory challenges.

Effects of Salmonella typhimurium lipopolysaccharide on broiler chickens

The effects of Salmonella typhimurium lipopolysaccharide (LPS) on the physiology of 3-wk-old broiler chickens were studied at 12, 24, and 48 h after a single intravenous injection of saline or LPS. Lipopolysaccharide elevated cloacal temperature by 3 h after injection, induced a diuretic response, and decreased BW gain. An increase in the relative liver weight was evident in LPS-treated birds at all time intervals, whereas a decrease in the relative weight of bursa of Fabricius was observed only at the 48-h time point. The plasma interleukin (IL)-6 and the blood heterophil concentrations were elevated at 12 and 24 h following LPS administration. These changes were not observed in control chickens or in LPS-treated chickens at 48 h. A decrease in the blood glucose concentration in LPS-treated birds at 12 h was accompanied by an elevation in the blood phosphate level. An increase in total plasma protein concentration was observed only at 24 and 48 h after LPS treatment. Comparative SDS-PAGE analysis of plasma proteins from these birds under nonreducing conditions showed some quantitative differences in four bands of proteins between saline and LPS-treated chickens. A protein corresponding to an approximate molecular weight (MW) of 65 kDa increased in LPS-treated chickens, and three other proteins with MW of approximately 39, 49, and 56 kDa showed reductions in concentration compared with saline-treated controls. These results show that LPS induces a number of physiological changes that may be responsible for the regulation of the acute phase response in chickens.

HEALTH OF TREE SWALLOWS (TACHYCINETA BICOLOR) NESTING IN PESTICIDE-SPRAYED APPLE ORCHARDS IN ONTARIO, CANADA. I. IMMUNOLOGICAL PARAMETERS

The degree of pesticide exposure and its effects on the immune system and its development were determined in 16-d-old tree swallow (Tachycineta bicolor) chicks from 4 sprayed apple orchards and three nonsprayed sites in southern Ontario, Canada, during 1994-1995. Persistent contaminant residues were measured in tree swallow eggs and in each chick hepatic ethoxyresorufin O -deethylase (EROD) activity; body, immune organ,and liver masses; lymphocyte blastogenesis response; respiratory burst and phagocytic responses; hematological evaluation; and histological development of thymus, bursa of fabricius, and spleen were determined. Chemicals sprayed on apple orchards were mainly ethylene bisdithiocarbamate and myclobutanil fungicides and organophosphorus, carbamate, and synthetic pyrethroid insecticides. During the period between oviposition of the first egg in each nest to d 16 after hatching, individual nests in orchards were exposed to between 4 and 11 individual chemical applications and up to 3 mixtures of pesticide sprays. Concentrations of pesticides, polychlorinated biphenyls ( PCBs), and lead and arsenic residues in tree swallow eggs and liver were low and not variable among sites except p,p '-DDE, which was as high as 2.29 mug/g wet weight in eggs. EROD activity was not different among sites. Organochlorine and trace metal residues and EROD activity were not correlated with any immune parameter. In sprayed birds, we found a significantly increased blastogenic response to pokeweed mitogen (12.5 mug/ ml). However, nests were initiated over a period of several weeks and we also found changes in other tree swallow immune parameters that were related to the date of chick collection. Hematological parameters, bursal and thymic masses, phagocytic response, and thymic development were all correlated with the day the chicks were 16 d of age. After accounting for the collection date of birds from each nest, we found cell proliferation in the cortex and delayed thymic involution correlated positively with increasing spray exposure. We also found that birds in sprayed orchards were slightly anemic compared to birds from nonsprayed sites, and there were smaller bursal masses and an increase in relative heterophil concentrations in the sprayed orchard birds. The local inflammation may have been caused by trematode parasite infections, although pesticide exposure also correlated positively with these parameters. This is the first study of the immunology and effects of current pesticide exposures in wild passerines; therefore it is difficult to predict the longterm consequences of the apparent stimulated immune systems in sprayed birds. However, some environmental contaminants that overtly stimulate the immune system in mammals have induced hypersensitivity and/or autoimmunity. Therefore we speculate that these effects are possible in tree swallows.

Heterophil Response to Intraperitoneal Challenge with Invasion-Deficient Salmonella enteritidis and Salmonella-Immune Lymphokines

The present work compared the accumulation of intraperitoneal heterophils in day-of-hatch chicks following treatment with Salmonella enteritidis-immune lymphokine (ILK) and challenge with various strains of Salmonella enteritidis (SE). Day-of-hatch chicks received ILK by intraperitoneal injection and were challenged 1 hr later by intraperitoneal inoculation with one of the following SE strains: a wild-type, SE 890034-3; a delta cya-12 delta cyp-11 avirulent vaccine strain, chi 4357; and an invasion-deficient strain, InvA::kan, chi 4420. Four hours after challenge heterophils were recovered from the peritoneal cavity by lavage. The concentration of heterophils in the recovered lavage fluid was determined. Heterophil concentrations increased in response to challenge with each SE strain but there was a lower response to the invasion-deficient strain. The difference was statistically significant. This diminished heterophil response to challenge with invasion-deficient salmonellae supports existing evidence that the initial defensive reaction occurs at the earliest stages of the Salmonella-host interaction.

A Leucocytopenia Induced in Chickens by Dietary Ochratoxin A , ,

Ochratoxin A was fed (0, .5, 1.0, 2.0, 4.0, and 8.0 μg/g) to broiler chickens from day-old to three weeks of age when the birds were bled and total leucocyte and differential counts were performed. Ochratoxin A significantly (P<.05) reduced leucocyte counts at every dose level of ochratoxin A administered. The leucocytopenia was characterized by an increase in the relative concentration of heterophils and decrease in the relative concentration of lymphocytes. From total leucocyte and differential leucocyte counts the number of circulating cells was calculated for each type of leucocyte. The total number of circulating lymphocytes of blood decreased significantly (P<.05) at every dose level of ochratoxin A administered, and the number of monocytes decreased at 2.0 μg/g and above. However, the number of circulating heterophils was not altered. These data demonstrated that ochratoxin A induced a severe leucocytopenia (lympocytopenia primarily and monocytopenia to a lesser extent) and implied that the functioning of the immune system might be altered.