Role of the Lymphocyte in Antibody Formation 87 



gen, the injection sites on the first day contained numerous readily visible, 

 well-preserved lymphocytes, a few heterophils, and a lew macrophages (Fig. 

 7-2); immunohistochemical stains for antibody were negative. Between days 

 one and three the number of lymphocytes decreased, and occasional large, 

 immature-appearing cells, resembling "Fagraeus' transitional cells" 14 or 



Fig. 7-4. Frozen section of cell transfer on the third day, stained for anti-BSA with use 

 of Coons' fluorescent-antibody technique. The positive cells have while cytoplasm and 

 are located around a medium-sized blood vessel, (x 800) 



"Rich's acute splenic tumor cells," 59 as well as smaller "preplasma" cells 

 appeared (Fig. 7-3). These cells tended to aggregate around nerves and blood 

 vessels. The first immunohistochemically demonstrated antibody was seen 

 by the third day (Fig. 7-4). Most of the antibody-containing cells were pre- 

 plasma cells. Some fluorescence was also present in the larger "transitional" 

 cells. Only a rare mature plasma cell was seen. By the filth day lymphocytes 



