Characterization of Plasmodium berghei antigens inducing blast transformation in immune rat lymphocytes.

Rat erythrocytes, infected with Plasmodium berghei, were disrupted by freezing and thawing or parasites were released by mechanical breaking of the agglutinated erythrocytes. The released soluble antigens, inducing blast transformation in non-adherent immune rat spleen cells, were fractionated by a sequence of salting out, ion exchange chromatography and gel filtration. At the final step a purification factor of 83.7-fold was achieved. This fraction contained three components discernible by SDS-PAGE of molecular weights 56, 66 and 72 kD respectively. The free parasites, also induced blast transformation in immune rat spleen cells. After disruption by freeze-thawing the majority of the active antigens was found in the sediment after centrifugation at 17,300 g.