Factors in the pathomechanism of chronic lymphocytic leukemia.

It has been shown that CLL is characterized by a piling up of highly differentiated lymphocytic cells. These cells have the structural and metabolic characteristics of a neoplastic cell line of B lymphocytes (except in cases of "T-cell CLL"). However, they lack the immunoglobulin-secreting ability of normal B cells, and are immunologically incompetent and inert. Next to this population, there is a normal but reduced population of B cells and a periodically slightly increased T-cell population. The accumulation of pathological cells is based on a 10-fold increase in proliferation of cells that have a 5-fold increase in their life span. In addition, there is a disturbance of exchange of cells between the intra- and extravascular pools. These characteristics clarify the development of the clinical picture: through packing of the bone marrow with pathological cells on the one hand, and the spleen on the other, anemia, thrombocytopenia, and finally granulocytopenia develop. The gradual displacement of normal B cells often leads to extreme hypogammaglobulinemia as the main component of a multifactorial syndrome of immune deficiency.