CD27 and systemic sclerosis: In addition, we examined clinical correlation of the affinity for topo I by dividing SSc patients into two groups, the high-affinity B cell-dominant group (n = 58) and the low-affinity B cell-dominant group (n = 53): the former had a higher frequency (>50%) of B cells with high affinity for topo I among CD27+ B cells, while the latter had a higher frequency (>50%) of B cells with low affinity for topo I (Table 1).