1. Researchers involved in ecology and toxicology, as well as many other aspects of avian biology, use phytohaemagglutinin (PHA) skin testing as a means of evaluating the immune status of individuals.



2. Immune function, one measure of individual quality, can be used as a sensitive, non-lethal variable that may be negatively affected in animals exposed to degraded, contaminated or otherwise disturbed ecological zones.



3. Typically this test has been applied by challenging one wing web with the immunostimulant PHA, while the other ‘control’ wing is injected with phosphate buffered saline (PBS). Injection sites on the wing web are measured before and 24 h after injection with PHA or PBS. The immune response is considered to be the difference between the two wings.



4. Results from PHA skin tests conducted on 608 birds in seven studies representing passerines, waterfowl, upland game birds and raptors are examined.



5. Numerous advantages to eliminating the PBS injection as the experimental control are: (i) decrease by half, the time required for testing; (ii) decrease handling-related stress on the birds (proportional to handling time); (iii) reduce the probability of errors at injection time; (iv) spare the other wing for different tests or uses (e.g. tuberculin DTH testing); and (v) decrease the coefficient of variation that is due to measurement inaccuracies.



6. The only disadvantage identified is that hypersensitive individuals (outliers) could be missed, which in this case represents 2 of 608 individuals.

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2435.1999.00338.x

Simplifying the phytohaemagglutinin skin‐testing technique in studies of avian immunocompetence

The activation of an immune response is beneficial for organisms but may also have costs that affect fitness. Documented immune costs include those associated with acquisition of special nutrients,...

/pdf/immune-activity-elevates-energy-expenditure-of-house-17nn2dh0pk.pdf

Immune activity elevates energy expenditure of house sparrows: a link between direct and indirect costs?

Summary
1Measurements of phytohemagglutinin (PHA)-induced tissue swelling are arguably the most popular surrogates for immunocompetence in wild birds. It is largely unresolved, however, whether the basic assumption underlying these measures is valid, particularly whether more swelling represents a ‘better’ or ‘stronger’ cell-mediated immune response.
2In this study we took a first step towards such validation by characterizing immune cell infiltration over time into the wing-webs (patagia) of PHA-challenged House Sparrows (Passer domesticus). Relative to saline-injected wing-webs, PHA-injected wing-webs displayed intensive infiltration of many immune cell types, including basophils, eosinophils, heterophils, lymphocytes, macrophages and thrombocytes. The abundance of most of these cell types changed over the course of the swelling response (6–48 h post-injection). Peak infiltration time varied depending on cell type. At several time points, significant correlations between the numbers of some cell types (particularly heterophils) and the degree of swelling were detected.
3Together, these data indicate that PHA-induced swelling is related to heightened immune cell activity in House Sparrows, but also that the PHA swelling response in this species is dynamic and involves both innate and adaptive components of the immune system. We thus caution against interpreting larger swellings as ‘greater cell-mediated immunocompetence’, given the complex nature of this immune response.

Phytohemagglutinin-induced skin swelling in birds : histological support for a classic immunoecological technique

1. Intra-brood competition and parental feeding effort are considered important determinants of survival of offspring in altricial bird species because they affect accumulation of fat reserves by nestlings. However, the causal relationship between rearing conditions and post-fledging survival might also be mediated by other mechanisms ; for example, the amount and quality of food provided by parents to each nestling might affect development of immune system organs and functions and, hence, the ability of offspring to cope with parasites and pathogens. 2. The hypothesis that parental feeding effort, food quality and brood size affect immunocompetence of nestlings was tested for the first time in the barn swallow, Hirundo rustica, Linnaeus. 3. The intensity of T-lymphocyte cell-mediated immune responsiveness was evaluated after intradermal inoculation of a lectin (phytohaemagglutinin) in a large sample of nestlings from unmanipulated broods and broods whose size had been manipulated immediately after hatching. 4. In unmanipulated broods, immune response, body mass and body condition were correlated negatively with brood size and positively with the rate of parental feeding to each offspring. Nestlings in enlarged broods had smaller immune response and body mass, and received less food per capita than those in reduced broods. 5. Broods artificially provisioned with a food rich in proteins showed larger immune response, but not larger body mass, as compared to unprovisioned controls. 6. We conclude that T-lymphocyte cell-mediated immune response as well as body mass is influenced by the level of parental investment and brood size, perhaps via its effect on competition for food. Since T-lymphocytes are fundamental components of avian immunity, and parasites are known to affect survival of their avian hosts, our results suggest a new pathway through which rearing conditions might influence offspring survival.

Immunocompetence of nestling barn swallows in relation to brood size and parental effort

ABSmAcr.-We investigated the effects of dietary protein quality on the development and functioning of the immune system in four-week-old Northern Bobwhite (Colinus virginianus) chicks. Chicks were fed isocaloric diets containing 8, 15, or 33% protein over a three-week period. Significant reductions in the rate of body growth were evident in chicks receiving 8 and 15% protein. Development of the bursa of Fabricius and spleen was significantly depressed in the 8% protein group compared to the other two treatments. Lymphocyte yields from dissociated lymphoid organs of chicks fed 8% protein were substantially reduced compared to birds fed higher levels of protein. In vitro lymphoproliferative responses of cultured splenocytes to mitogenic stimulation (concanavalin A, pokeweed mitogen, and Salmonella typhimurium), white-blood-cell counts, and in vivo measures of humoral immunity did not differ among dietary treatments. Cell-mediated immune function, as measured by an in vivo hypersensitivity response to an intradermal injection of a T lymphocyte-dependent mitogen (phytohemagglutinin), was significantly suppressed in the 8% protein group compared to the other two treatments. Several measures of immune-system development and function were significantly correlated with body mass change during the trial. Results indicated that four-week-old Northern Bobwhite chicks fed an 8% protein diet for three weeks may have difficulty expressing a competent immune response to pathogenic challenge in the wild. Received 30 January 1992, accepted 25 November 1992.

Relationship Between Protein Nutritional Status and Immunocompetence in Northern Bobwhite Chicks

Suppression of Phytohemagglutinin Skin Response in Thymectomized Chickens

Intranasal tumors (papillary adenomas or adenocarcinomas) of the ethmoid olfactory mucosa of sheep were investigated by light and electron microscopy. The fine structure of the tumor cells was characterized by the presence of numerous secretory granules. Viral particles, which were morphologically similar to a visna-maedi virus, were detected in all tumor tissues and in 3 of 4 cultures examined. The particles (about 97 nm) had an eccentrically located electron-dense core and numerous spikes on their surfaces. The RNA-dependent DNA polymerase activities in the tumor cells or the cultured cell from the tumor were greater than those in the normal intranasal tissues or the cultured cells from the choroid plexus. Viral particles similar to herpesvirus were also detected in 1 culture.

Intranasal tumor of the ethmoid olfactory mucosa in sheep.

SUMMARY Observations of the feather pulp from chickens inoculated with Marek's disease (MD) virus revealed diverse lesions similar to those in the peripheral nerves of chickens infected with MD. These lesions were categorized as follows: Ri-type lesions = from minimal perivascular to diffuse infiltration of small lymphocytes mixed with a few medium lymphocytes or blast cells; R2-type lesion = edema and cellular infiltration consisting of plasma cells and small lymphocytes; and T-type lesion = tumorous proliferation of lymphoid cells predominantly composed of medium lymphocytes or blast cells. Chronological observations of the feather pulp biopsies taken at 2-week intervals from individual chickens revealed the lesion progression RI-type --> T-type, or R1-type --> R2-type. The former progression was usually seen in birds showing evidence of both persistent nuclear-inclusion (NI) formation in the feather-follicle epithelium (FFE) and development of lymphoid tumors in the viscera. The latter progression was seen exclusively in chickens that showed transient NI formation in the FFE, regardless of the incidence of MD.

Y. Fujimoto

Papers

Suppression of Phytohemagglutinin Skin Response in Thymectomized Chickens

Intranasal tumor of the ethmoid olfactory mucosa in sheep.

Chronological Observations of Feather Pulp Lesions in Chickens Inoculated with Marek's Disease Virus

The effects of Escherichia coli endotoxin as a trigger for hepatic infection of rabbits with Fusobacterium necrophorum.

Heterotransplantation of natural bovine lymphosarcoma to nude mice