Table 1.

Differential effects of altering the relative concentrations of FL, SF, and IL-3 on LTC-IC and CFC expansion

					Analysis of effect on LTC-IC expansion
Cytokine concentration, ng/ml			Progenitor expansion*		Normalized effect†	Significance of normalized effect‡
FL	SF	IL-3	LTC-IC	CFC
300	300	60	45  ±  15	76  ±  19	−0.29	NS
300	300	2	33  ±  12	31  ±  5	0.85	NS
300	10	60	22  ±  6	76  ±  28	−0.26	NS
300	10	2	18  ±  9	41  ±  30	1.2	P < 0.05
10	300	60	4  ±  2	62  ±  33	0.73	NS
10	300	2	4  ±  3	39  ±  11	0.49	NS
10	10	2	4  ±  1	28  ±  15	N/A	N/A
10	10	60	0.3  ±  0.1	68  ±  37	−0.83	P < 0.10

^*Values shown are the mean ± SEM of data from three experiments. 

^†Effects of individual cytokines (main effects) within the mixture were calculated from the sum of differences between all of the normalized LTC-IC expansion values (see Materials and Methods) obtained with that cytokine at the higher vs. the lower concentration tested [the levels of the other cytokines being constant (15)]. Effects of elevated levels of multiple cytokines (interaction effects) were determined by analysis of variance (15). All effects were determined relative to the cultures where all three cytokines were present at the lower level such that a change in cytokine concentration with no overall effect would have a value of 0. The SEM of the normalized effect on LTC-IC expansion was 0.24. 

^‡Significance was determined from a comparison of the normalized effect and the SEM of the normalized effect of the elevated cytokine concentrations on LTC-IC expansion. NS, not significant (i.e., P > 0.1); N/A, not applicable.