[Evolution of splenic lympho-reticular populations during the immune response "in vitro" in the chick (author's transl)].

The different types of cell population in organotypic cultures of spleen from chicken immunized with Salmonella paratyphi B were enumerated. The kinetics of immunoglobulin and of antiflagellar antibody synthesis followed the cellular variations observed. Two phases were generally observed: one was characterized by a considerable decrease in small and medium-sized lymphocytes by a lytic process and the appearance, by transformation and/or multiplication, of a large population of hyperactive macrophages. The IgM and IgG synthesized between the 2nd and 9th days only partially consisted of antiflagellar antibodies; some were synthesized probably by large basophilic cells and others by the few plasma cells which were observed, generally isolated on the prints. The second phase, from the 11th to the 21st day, manifested a narrower antibody specificity in that all the IgG, the only immunoglobulin synthesized during this period, might be entirely absorbed by the antigen and corresponded to the proliferation of a new lymphoreticular population. A close cellular cooperation seemed to occur at this stage between these two types of population, the macrophages appearing to stimulate lymphopoiesis. Colonies of plasma cells, characteristic of this phase, appeared from the 13th day. These two phases were separated around the 9th day be a brief period of cellular depression. Although the transformations, the contacts and the islets observed among the lympho-reticular populations indicated their plasticity and their capacity for change during the reaction, it must be noted that there was no in vitro example of antibody synthesis occurring without the simultaneous presence of lymphocytes, macrophages and pyroninophile cells.