Table 1. Colony formation assays and cytogenetic analyses on normal volunteer marrow MNC.

Cultures		Granulocytes (G)	Eosinophiles (Eo)	Macrophages (M)	Erythrocytes (E)	Mixed colonies (GM)	Blasts	Total no.
Week 0 control		49	2	61	128	12	7	259
8-Cl-cAMP (100 μm)		27	4	18	100	7	9	145
Week 5 control	ADC	57	2	16	6	2	5	88
8-Cl-cAMP(100 μm)	ADC	70	2	10	30	14	22	148

Data obtained after treatment of normal marrow MNC with 8-Cl-cAMP are summarised. The cells were resuspended at 2.5 × 10⁵ cells ml⁻¹ as described in Figure 1. The effects of treatment with 8-Cl-cAMP (one single exposure of the cells for 24 h) on colony formation was observed at week 0 and after week 5.2 × 10⁵ cells ml⁻¹ were plated in soft agar for colony formation in week 1 or after long-term culture. The nonadherent cell fraction did not yield significant amounts of colonies with or without 8-Cl-cAMP treatment after 5 weeks, thus only the adherent cells (ADC) are shown. Colonies were judged by their typical histological appearance according to haematological criteria: G=granulocyte; Eo=eosinophiles; M=macrophages; E=erythrocytes; GM=mixed colonies, Granulocytes and macrophages.