Immunohistochemical study of bone marrow sections in CLL.

T lymphocytes and dendritic reticulum cells (DRC) were studied in frozen-cut bone marrow sections of 35 patients with chronic lymphocytic leukemia (CLL) (infiltration patterns: interstitial 8, nodular 6, mixed 9, diffuse 12) and 13 cases of low grade non Hodgkin's lymphoma (NHL) (centroblastic/centrocytic 7, centrocytic 3, lymphoplasmacytoid 3) with bone marrow involvement. In contrast to the usual findings in normal bone marrow, in CLL and low grade NHL CD4 positive cells were more numerous than CD8 positive cells. Whereas in NHL CDR were large and occupied all the nodule, in CLL were small and located in the center of the nodule. These findings can be of interest in the study and differential diagnosis of lymphoproliferative disorders.