Parasites and tradeoffs in the immune response of female red jungle fowl

Reproduction and survival are influenced by parasites, and recently, the ab ility of the immune system to fight infection has been included in life his tory theory. A condition dependent immune response predicts tradeoffs withi n the immune system and condition dependent tradeoffs with other life histo ry traits. Female red jungle fowl (Gullus gallus) parasitized with an intes tinal nematode (Ascaridia galli) had a higher concentration of eosinophils than controls, and parasitized and control females responded differently to injections of phytohemagglutinin (PHA). PHA injections stimulated an incre ase in granulocytes in parasitized females relative to controls. Although p arasitized Females had greater circulating levels of the white blood cells that are involved in the cutaneous hypersensitivity response, control femal es exhibited greater swelling of the wing web six hours after injection. A. galli seemed to slow the cellular immune response to injections of PHA, su ggesting a tradeoff within the cellular component of the immune system. Par asitized and control females differed in the relationship between immunoglo bulin G (IgG) and the strength of the cutaneous hypersensitivity response. The decrease in cutaneous hypersensitivity with increasing IgG in parasitiz ed vs control females suggests a condition dependent tradeoff between the c ellular and humoral components of the immune system.