Autologous stem-cell transplantation restores the functional properties of CD14+CD16+ monocytes in patients with myeloma and lymphoma.

The CD14+CD16+ monocytes appear to be important to immune defense against infection, as these cells are very potent with respect to tumor necrosis factor (TNF) production, phagocytosis, and antigen presentation. Myeloablative high-dose chemotherapy (HDT) and subsequent autologous stem-cell transplantation (ASCT) are being used increasingly for therapy of hematological malignancies, but the pronounced immunosuppression renders the patients prone to infection. To determine the functional properties of CD14+CD16+ monocytes under these conditions, 15 patients with lymphoma or myeloma were examined. Before HDT, the ratio of CD14+CD16+ cells to the population of the classical CD14++ monocytes was 0.28 +/- 0.12; this ratio changed during the course of HDT and ASCT in favor of the CD14+CD16+ monocytes to a maximum of 12.4 +/- 7.8 (P<0.001) on day 3.5 +/- 1.6 after transplanation (Tx) and returned to 0.11 +/- 0.07 (P<0.001) after engraftment on day 11.3 +/- 2.2. Although the absolute number of classical CD14++ monocytes declined to less than 1/microl at the nadir, the number of CD14+CD16+monocytes fell from 29.7 +/- 9.8/microl to 4.5 +/- 3.0/microl at the nadir and increased to 13.8 +/- 9.8/microl at the day of discharge from the hospital. Flow cytometric analysis of phagocytosis of fluorescein isothiocyanate (FITC)-labeled Escherichia coli showed that 30 +/- 10% CD14+CD16+ monocytes of patients were FITC-positive before Tx, and at engrafment, the percentage of FITC-positive cells had doubled to 60 +/- 6% (healthy controls, 41+/-7%). When determining generation of reactive oxygen species after E. coli ingestion, the CD14+CD16+ monocytes showed a decreased response before Tx (32+/-12% positve cells), which increased to 53 +/- 24% after ASCT. The median fluorescence intensity of human leukocyte antigen (HLA)-DR expression on the CD14+CD16+ monocytes increased from 11 +/- 6 before Tx to 17 +/- 11 after Tx, and the production of TNF after lipopolysaccharide showed no remarkable difference (46+/-13 vs. 49+/-14 channels). At the same time, expression of TNF and of HLA-DR showed a dramatic decrease in the CD14++ monocytes. Taken together after stem-cell Tx, the function of the CD14++ monocytes is impaired, and the functional properties of CD14+CD16+ monocytes recover, indicating that these cells may be important for defense against infections post-ASCT.