Generalized monocyte deficiency in leukaemic reticuloendotheliosis.

Examination of the blood of 40 patients with leukaemic reticuloendotheliosis (LRE) revealed a drastic reduction in monocyte numbers (mean 74/microliter) when compared to a normal group of 33 (mean 442/microliter). Repeated blood studies in 8 LRE patients were made over periods of 2 months to 5 years and monocytopenia was observed to be a persistent phenomenon. Similarly, tissues from 29 patients showed an overall decrease in numbers of monocytes/ histiocytes when compared with those of 73 control subjects. Skin window examinations in all 11 patients so studied showed marked reduction or absence of monocyte response to inflammation. 2 exceptional cases to this trend are noted. In one, circulating monocyte levels remained normal over a 14-month period while examinations of blood and marrow in this case showed few hairy cells. In another case, severe and persistent monocyte deficiency was noted during a 2-year period of unsuccessful treatment. When he eventually responded to low dose chlorambucil and his Hb rose from 40-140 g/l and WBC became normal, the number of circulating monocytes also became normal.