SUPPRESSING EFFECTS OF PURIFIED EOSINOPHILS DERIVED FROM GUINEA PIGS SENSITIZED WITH ASCARIS ANTIGEN ON LYMPHOCYTE-BLASTFORMATION

Highly purified eosinophil (Eos) fractions were obtained from peritoneal exudate cells of guinea pigs immunized withAscarislumbricoides swumantigen. (Asc) . These Eos suppressed the in vitro DNA synthesis of the lymph node cells (LNC) sensitized with Asc and then activated by this antigen or phytohemagglutinin (PHA) . Although addition of Eos did not affect the viability of LNC in vitro, the blastformation of LNC was suppressed remarkably when 5-10×105purified Eos were added to 106LNC within 48 hr after the start of stimulation by Asc. The suppressive effects of Eos on the blastformation of LNC immunized with complete Freund's adjuvant with or without ovalbumin were observed when stimulated with purified protein derivatives or ovalbumin. Such suppression was observed beyond the barrier of animal strain specificity; Eos from Hartley guinea pigs suppressed proliferation of LNC from either strain 13 or strain 2, and Eos from strain 13 suppressed that from strain 2. Such suppressing activity of Eos was reduced by heating them at 56 C for 1 hr or by sonication.