INTERRELATIONS 



(iii) Plasma cells are always associated with lymphocytes 

 and much of the controversy as to which is the important 

 antibody-producing cell seems to have turned on the purely 

 verbal point as to whether something should be called a 

 lymphocyte or an immature plasma cell. All transitions 

 between small lymphocytes and plasma cells can be observed 

 and there is equally evidence for transformation of more 

 primitive cells, reticular cell or large lymphocyte into im- 

 mature and eventually mature plasma cells. Marshall 

 derives the plasma cell wholly from the primitive reticulum 

 cell via what he calls an activated reticulum cell. He 

 mentions one type of generalized myelomatosis in which the 

 neoplastic cells include both lymphocytes and plasma cells. 

 If on activation a lymphoid cell can take on the character of 

 a primitive reticulum cell, it follows automatically that, under 

 appropriate conditions, it can give rise to plasma cells. 

 There is a suggestion from the work of Bjornboe, Gormsen 

 and Lundqvist (1947) that in grossly hyper-immunized 

 rabbits collections of mature and probably non-functional 

 plasma cells accumulate in the fatty tissue of the renal pelvis, 

 but there is very little other evidence of what is the fate of, 

 for example, the large numbers of plasma cells which develop 

 in response to a secondary antigenic stimulus. 



(iv) Macrophages, the reticulo-endothelial system of 

 Aschoff, include fixed macrophages, wandering tissue macro- 

 phages or polyblasts and the blood monocytes. Opinion 

 holds that they can be derived from similar cells, from 

 lymphocytes or from primitive reticular cells. Under appro- 

 priate conditions they can become fibroblasts. It has been 

 claimed that polyblasts can become immature antibody- 

 producing plasma cells. Taliaferro (1949), looking at the 

 situation as an immunologist, brings the cells concerned into 

 a single mesenchymal cell pool, the lymphoid-macrophage 

 system. Particularly in protozoal infections he finds clear 

 evidence (of conversion) of lymphocytes into macrophages. 



Marshall, who identifies macrophages as metalophil cells, 



115 8-2 



