Biologic Activities of Lymph Node Cells Fractionated on Bovine Plasma Albumin

[摘要] For the study of some characteristics of antibody-forming cells optimal conditions were determined for enrichment of plaque-forming cells (PFC) in suspensions of rabbit lymph node cells (LNC) by density gradient centrifugation in bovine plasma albumin. The most enriched fractions contained 5 to 15 times their concentration in the original unfractionated cell suspension. There was a correlation between the size distribution of the LNC and their density, the smallest cells appearing in the high density region of the gradient, and the medium and large cells in the low density region.PFC obtained from rabbits 3 to 4 days after secondary injection of Shigella paradysenteriae were all in low density fractions. On days 4 to 5 some PFC appeared among the highest density fractions, with a gradual shift in that direction until, by day 10, all PFC were in high density fractions. The plaques produced by cells of the low density region of the gradient were prevented by treatment of the plates with 2-mercaptoethanol (2-ME), whereas the antibody produced by the high density cells was 2-ME resistant. Mouse spleen cells and LNC did not show such high density PFC at these times.The antigen-binding capacity of LNC from normal and immunized rabbits was studied with 131I-labeled soluble Shigella antigen. It was found that the antigenbinding profile of LNC from immunized rabbits followed the profile of the PFC, but among cells obtained from normal rabbits, or rabbits immunized with an unrelated antigen, high density cells were found to bind the antigen.The biosynthetic activity of mouse spleen cells was measured by the incorporation of radioactive amino acids, uridine and thymidine into macromolecules. The density gradient fractions containing the PFC showed greater incorporation of the precursors than the rest of the population.

[学科分类] 生物科学（综合）