Quantitation of antibody production in mouse bone marrow during the secondary response to sheep erythrocytes

The antibody production per organ was quantitated during the secondary response to sheep erythrocytes (SRBC) by measuring the hemolysin production in short-term cultures of spleen and bone marrow cells. Using this assay it was shown that during the first 5 days of the response the spleen is the major site of antibody production, whereas thereafter the bone marrow is the major source. By comparing the hemolysin production per organ and the total number of hemolysin-producing plaque-forming cells (PFC) per organ it was shown that the mean antibody production per PFC varied both in spleen and bone marrow during the secondary response. The mean antibody production per PFC was minimal when the PFC response was maximal. In the bone marrow the mean production per PFC decreased from day 3 to day 5, probably due to immigration of low producing PFC from the spleen. Beyond day 6 the production per cell increased in both spleen and bone marrow, indicating a further maturation of the PFC.