Preliminary Studies on the Use of Ferritin‐Conjugated Antibodies to Plasmodium berghei *

SYNOPSIS. The feasibility of applying immunoferritin technics in malarial antibody studies was explored using the asexual erythrocytic stages of Plasmodium berghei. Anti‐ P. berghei antibodies were induced in rats by repeated infection and in rabbits by immunization with French press‐ or saponin‐prepared antigens. Ferritin tagging was observed in thin sections of some freed and intracellular P. berghei parasites after exposure to ferritin‐labeled antibodies. A more extensive localization of ferritin was observed in cells subjected to the indirect versus the direct method of incubation. With formalin as a prefixative as opposed to glutaraldehyde, an increased ferritin tagging and the distribution of ferritin at intracellular sites was evident. These observations are discussed in terms of the damage and associated increase in permeability which often appeared in our formalin‐fixed tissue. Controls with normal serum or normal uninfected erythrocytes differed in ferritin localization from their corresponding test materials in only a few trials. The need for antibody preparations as free as possible from reactivity to host components became obvious. The positive results obtained when ferritin alone (especially TC‐modified ferritin) was applied in excess indicated a nonspecific binding and the necessity of purifying the conjugates of unbound ferritin was stressed. Native ferritin was found in the large double membranebound host inclusions, small vesicles and residual body of P. berghei.