Direct contact with stroma enhances the suppressive effects of CD38 ligation in 32D cells expressing human CD38.

Cells were cultured for 7 days without or with bone marrow-derived stromal layers. In the latter cultures, 32D cells were either in direct contact with stroma (“Contact”) or separated from stroma by a 0.4-μm porous membrane (“No contact”). Results are expressed as mean (± SD) percent cell recovery in the presence of anti-CD38 (T16) as compared with parallel cultures with a control nonreactive Ig. The number of experiments for each culture condition is indicated.