Monocyte dysfunction in patients with multiple myeloma and lymphoplasmacytic disorders is related to serum paraprotein levels

We have investigated monocyte function in 30 patients with lymphoplasmacyti c disorders and in 21 age and sex matched normal controls, Marked abnormali ties of all facets of monocyte function were demonstrated in six patients w ith multiple myeloma (MM) and a single patient with Waldenstrom's macroglob ulinaemia (WM) plus significant paraproteinaemia. Serious infection occurre d in three of these patients, An inverse relationship between the level of the serum paraprotein and impairment of monocyte phagocytosis plus killing of Candida albicans was observed. Crossover studies suggested that these ab normal findings were constitutive and not reversed by removal of the serum paraprotein, The data suggest that monocyte function is constitutively abno rmal in patients with MM and can be further, but reversibly, inhibited by h igh paraprotein levels. Further research is required to confirm these findi ngs, ascertain whether monocyte function can be normalized using chemothera py or growth factors, and if so, whether their tumouricidal functions could be harnessed in the treatment of this currently incurable condition.