MS4A1 and neoplasm: In contrast, it had a variable influence on tumour targeting in the two patients with preserved circulating CD20+ lymphocytes, enhancing uptake in three lesions (of which two were visceral) by improving biodistribution and preventing sequestration of the radioconjugate by the antigen sink, while impairing targeting of other tumour sites due to partial saturation with unlabelled rituximab.