CD33 and neoplasm: While total leucocyte infiltration level did not affect response to therapy, we did find a significant increase in immature CD33+HLA-DR− population tumor infiltration in non-responders (5.26 ± 1.23, n = 14) compared with responders (1.69 ± 0.35, n = 11, P = 0.02; Figure 4C).