Initiation of Primary-Type and Secondary-Type Antibody Responses to Bacteriophage φX 174 in Vitro

Abstract

Summary Rabbit lymph nodes were maintained in organ culture for 2 to 3 weeks. Tissue integrity and organization were well preserved with survival and formation of all cell types, e.g., blast cells, lymphocytes, plasma cells and macrophages. A primary-type anti-φX 174 response was initiated in vitro by φX 174 stimulation in cultures of lymph nodes removed from normal rabbits. On the other hand, a secondary-type response was initiated and produced in cultures of lymphoid tissues from rabbits immunized with φX 174. The kinetics of these two types of antibody responses were presented and are summarized as follows: The average peak k representing antibody activity was 0.1 in the primary response, whereas it was 124 in the secondary response, i.e., a difference of approximately 1000.In the primary response, 19 S antibody formation preceded that of 7 S, whereas 7 S antibodies were produced throughout the secondary response.In the primary response, 19 S antibodies were the predominant antibody type synthesized and 7 S, if any, only in small quantities. In the secondary response, 7 S antibodies were the only antibody type detected.Peak antibody production in the primary response was reached more than 3 days earlier than that in the secondary response.In the primary response, antibody production usually decreased steadily after the peak, whereas in the secondary response, it continued at a high level.The primary antibody response did not appear to be accompanied by increased mitotic activity, whereas, in the secondary response, mitotic activity increased prior to peak antibody production.There was a direct relationship between the concentration of φX 174 and the initiation of primary and secondary anti-φX 174 responses. The higher the concentration of the antigen, the greater was the induced antibody response. Lower concentrations of φX 174 were required to initiate a secondary response, e.g., 105 PFU of φX 174/ml failed to initiate a primary response but did initiate a secondary response. Lower concentrations of φX 174 also elicited a maximal secondary response, e.g., 108 PFU of φX 174/ml elicited a maximal secondary response, while 109 PFU of φX 174/ml failed to elicit a maximal primary response. No primary anti-φX 174 response could be detected in cultures of adult rabbit spleen and thymus under the present experimental con- The antibody responses initiated and produced in vitro and in vivo were compared and discussed.