Treatment with αCD20 and αCD137 reduces blood B-cell numbers in mice bearing B-cell lymphoma. Blood samples were collected for hemogram assessment according to the experimental design shown in (A). 1 × 105 BL3750 cells were injected i.v. at D0, and followed by treatment with control Ig (2A3, 250 μg i.p.) or anti-CD20 (clone 5D2, 250 μg i.p.) on day 4, and anti-CD137 (clone 3H3, 100 μg i.p.) either alone or in combination on day 5 in C57BL6 WT or various FcR-deficient mice, as indicated. Peripheral blood lymphocyte (B), and B cell numbers (C). Results are representative of one experiment n = 6 per group. Statistical analysis was calculated using Multiple T tests using the Holm–Sidak Method for multiple comparisons, where *p < 0.05 was considered statistically significant between respective anti-CD137 (clone 3H3), anti-CD20 (clone 5D2), 5D2 + 3H3 groups versus (2A3) isotype control-treated mice.