Transfer of immunity to Ancylostoma caninum infection in pups by serum and lymphoid cells.

The immunity of pups that had been double-vaccinated with X-irradiated Ancylostoma caninum larvae was passively and adoptively transferred to susceptible pups using serum or lymphoid cells, or serum and lymphoid cells. The immunity of recipient pups was demonstrated by a high degree of resistance to the establishment of adult hookworms after challenge inoculation of normal A. caninum larvae. Variation in the efficiency of serum and cells to act as vehicles for transfer of immunity was noted in different experiments, and was probably associated with the age of donor pups. However, within each experiment the results were remarkably uniform and quantitative relationships were observed between dose rate of serum and cells and success of passive and adoptive immunization. Delayed hypersensitivity was transferred to recipient pups as shown by significant increases in skin thickness 24–48 hours after active penetration of hookworm larvae.