Differentiation of lymphocytes in the mouse bone marrow. III. The adoptive response of bone marrow cells to a thymus cell-independent antigen.

The response of mouse spleen cells to the T cell-independent antigen dinitrophenylated polymer of flagellin (DNP—POL), has been studied using an adoptive transfer system, and compared with the response of bone marrow cells. Spleen cells showed a complex cell dose—response relationship, with a markedly discontinuous curve, for assays performed before day 9 after transfer and antigen challenge. This discontinuity could be explained by a delay in attainment of the peak response for lower cell inocula. The curve became linear on a log—log scale when spleens were harvested on days 9 and 10 post-transfer. Bone marrow cells gave a lower response than would be expected from their lymphocyte content. This response increased progressively with a delay before antigen challenge in the irradiated recipient or in tissue culture prior to cell transfer, suggesting a functional maturation in this cell population, whereas the performance of spleen cells fell off under similar circumstances. The findings were consistent with, but could not prove, the hypothesis that the immediate precursors of anti-DNP antibody-forming cells in bone marrow were high surface immunoglobulin density small lymphocytes that had arisen locally from precursors lacking detectable surface immunoglobulin, by a non-mitotic maturation.