Absolute monocyte count trichotomizes chronic lymphocytic leukemia into high risk patients with immune dysregulation, disease progression and poor survival.

Peripheral absolute monocyte count (AMC) has been reported to correlate with clinical outcome in different types of cancers. This association may relate to alteration in circulating monocytic subpopulations and tumor infiltrating macrophages. In this study we evaluated the clinical significance of peripheral AMC in 80 treatment naive patients with CLL. Measurement of AMC was based on direct morphological enumeration, due to our findings that complete blood count data may yield incorrect monocytes enumeration values in CLL. The median AMC in patients with CLL was within normal limits, however the AMC range exceeded the values of healthy individuals. The AMC trichotomized patients into 3 distinct sub-groups with different characteristics and outcomes. High AMC patients were younger and had higher absolute lymphocytes count, while patients with low AMC had prominent immune dysregulation (lower serum IgA levels, susceptibility to infections and a tendency for positive direct anti-globulin test). The low and high AMC patients had a shorter time to treatment compared to the intermediates AMC subgroups, whereas low AMC was associated with increased mortality caused by infectious complications. In conclusion, AMC quantification during the disease course classifies CLL patients into subgroups with unique clinical features and outcomes.