Mononuclear leucocyte chemotaxis in the chicken. Definition of a phylogenetically specific lymphokine.

Chicken leucocytes when stimulated with purified protein derivative (PPD), a specific antigen or concanavalin A (Con A), a nonspecific mitogen, produced a soluble factor which was chemotactic for homologous monocytes. The production of this factor, by PPD-stimulated spleen cells from PPD-immunized chickens was found to be a correlate of delayed skin reactivity. Leucocytes from the blood, spleen and thymus of chickens produced measurable amounts of mononuclear leucocyte chemotactic factor (MNL CTX); however, bursal lymphocytes failed to synthesize this mediator. Chicken MNL CTX was heat stable (56° for 30 minutes), nondialysable, remained active if frozen and thawed, and had an estimated molecular weight of 12,500 as determined by molecular sieve chromatography and sucrose density ultracentrifugation. Moreover, this lymphokine was sensitive to treatment with pepsin and trypsin but not with neuraminidase. These results indicate that chicken MNL CTX is a protein whose activity is independent of sialic acid. The physical characteristics of chicken MNL CTX are remarkably similar to those of a chemotactic lymphokine recently defined in man. However, chicken MNL CTX was not active in attracting human, guinea-pig or rabbit MNL, and chicken MNL failed to migrate in response to human or guinea-pig lymphokine CTX. These findings indicate that MNL CTX is a lymphokine whose activity is phylogenetically restricted.