The Plasma Cellular Reaction and Its Relation to the Formation of Antibodies in Vitro

Summary During secondary response, elicited in sensitized rabbits by means of intravenous injections of antigen, a great increase in the number of plasma cells (pl.c.) in the spleen was recorded simultaneously with the increase of circulating antibodies. Pl.c. were confined almost exclusively to the red pulp, especially after the injection of living S. typhi. They originated apparently from reticulum cells, passing through a chain of development: transitional cell → immature pl.c. → mature pl.c. Pieces of spleen were excised at different times during the period of antibody formation in rabbits, differential cell counts were made and the capacity of excised splenic tissue to form antibodies in vitro was investigated. The following observations were made: The a mount of antibody liberated in plain tissue extracts, under conditions preventing growth or metabolism of cells, was very low, whereas significant yields were obtained in tissue cultures. The capacity of the red pulp abundant in pl.c. to produce antibodies in vitro was considerably superior to that of lymph follicles, rich in lymphocytes but devoid of pl.c. Antibody production was comparatively poor in tissue containing only transitional cells, reached a maximum when numerous immature pl.c. were present and receded when predominantly mature pl.c. were found. After intravenous injections the antigen accumulated in those places where pl.c. subsequently developed. The conclusion is drawn that antibodies under the conditions of the experiments, are formed by cells of the R.E.S., passing through a chain of development, the final link of which is the mature pl.c. The author takes this opportunity of thanking Professor F. Henschen, Professor G. Olin and Doctor S. Gard for their interest in this work and valuable criticism. The work has been facilitated by grants from the Foundation Therese and Johan Anderssons minne.