Lymphocytes: Origin, Structure, and Interrelationships 15 



sions in "reticulum cell macrophages" of a lymph node imprint as well. Heil 

 meyer and Begemann 41 also show a colored plate of a dry film preparation 

 from a hyperplastic lymph node. In this group of cells, we can name hemat- 

 opoietic reticular cells, reticular lymphocytes, and immature lymphocytes 

 which are all often classified as lymphoblasts. 



In addition to these lymphocytic precursors, plasmablasts and plasma cells 

 are present in remarkably variable numbers. As indicated previously, 1 the 

 immature plasma cells are not always easily distinguished from the more 

 basophilic precursors of lymphocytes. Morphologically one can produce con- 

 vincing series of transitional cells from the large perivascular (perithelial) 

 reticular cell to the plasma cell or from large basophilic hematopoietic retic- 

 ular cells and/or reticular lymphocytes to plasma cells. The interrelationships 

 of reticular cells, lymphocytes, and plasma cells have been emphasized by 

 Downey. These interrelationships are presented in diagram form by Trow- 

 el]. 20 Two more distinct cell series are included in the schema of Heilmeyer 

 and Begemann (Plate 1/2 of Reference 41 ) . 



INTERRELATIONSHIPS 



The implications of the interrelationships in regard to the formation of 

 antibodies have recently been discussed by Fagraeus 42 who stated, "The im- 

 mature plasma cell stage is to me the morphological manifestation of a cell 

 at the point of maximal antibody formation." She stressed "the probability 

 that antibody production commences in young undifferentiated cells, not in 

 plasma cells or mature lymphocytes present in the body before the injection 

 of antigen." 



Karyometric analyses of human cells from lymph glands 43 ' 45 are interpreted 

 as indicating that "possibly the only function of basophilic germ centre cells 

 may be the production of cells" 43 and that the basophilic stem cells of the 

 pulp of lymph nodes "belong to the plasma cell series and therefore can be 

 called plasmablast and proplasmablast." 45 The illustrations in these papers 

 are excellent, but it is difficult to see how the problem can be solved on the 

 basis of nuclear volume since the latter can show great variation. For example, 

 large and small myelocytes are easily identified, and I have often seen the late 

 telophase of mitosis which would result in two "daughter" normoblasts with 

 apparently remarkably different nuclear volumes. The presence of plasma- 

 blasts 4,i ' 4T in the blood in German measles, infectious hepatitis, and infec- 

 tious mononucleosis is well recognized. However, I Avas surprised to find 

 plasma cells in the blood in one case of agammaglobulinemia. More inter- 

 esting was a recent case (etiology of condition unknown) with a remarkable 

 peripheral plasmacellular reaction comparable to that of German measles in 

 which the circulating immature plasma cells did not contain gamma globu- 



