Influence of HA’ase on myelopoiesis in LTBMC. (A) Nonadherent cells from myeloid LTBMC in the absence of HA’ase (control) or treated with HA’ase (Streptomyces HA’ase, Calbiochem; 0.1 U/mL) were harvested once per week, and their number was counted. Standard error (SE) was calculated from results obtained with 3 independent cultures. The insert shows the dose-dependent effect of HA’ase on the production of nonadherent cells in LTBMC after 4 weeks in culture. The bars indicate SE calculated from 3 independent wells each. (B) The production of clonogenic cells in either control LTBMC or in LTBMC treated with HA’ase (0.1 U/mL) was measured by the CFU assay (Materials and Methods). Nonadherent cells were harvested from LTBMC and plated in semisolid culture in the presence of IL-3 (Materials and Methods). SE was calculated from results obtained from 3 independent wells.