Table 1.

The number of CD154-expressing cells influenced B-lymphocyte differentiation and proliferation

				Proportion of positive cells3 (%)		Ig secretion4(ng/106 cells/hr; mean ± SD)
L4.5:B cell ratio1	Number of CD154/B cell1	Expansion of CD19+ cells2(× 106)	Viability2(%)	CD27+	CD38+	IgG	IgM	IgG:IgM ratio
1 : 2	8000–13000	333	96	5.7	1.2	34 ± 2	47 ± 3	0.72
1 : 5	3000–5000	839	96	21.2	9.2	62 ± 8	26 ± 2	2.4
1 : 10	1700–3000	634	95	25.9	14.3	70 ± 6	12 ± 1	5.8
1 : 25	700–1000	189	89	31.3	31.2	181 ± 36	16 ± 1	11.3
1 : 50	200–500	56	82	35.4	34.6	223 ± 8	25 ± 2	8.9
1 : 100	<250	4	75	38.7	43.4	–	–	–

These results are representative of two independent experiments. Ig, immunoglobulin; SD, standard deviation.

¹CD19-purified human peripheral B lymphocytes containing 31% CD27⁺ cells (375 000 cells/ml) were stimulated in the presence of variable numbers of CD154⁺ L4.5 cells and in the presence of interleukin (IL)-2, IL-4 and IL-10. Ranges of CD154 molecules shown are based on an average of 21 000 ± 25% molecules per L4.5 cell. Parental L929 cells were added as needed to adjust the total number of L cells (L4.5 + L929) to 500 000 cells/well.

²Viability and B-cell expansion were evaluated on day 14.

³The percentage of CD19⁺ CD27⁺ (CD27⁺) and CD19⁺ CD27⁺⁺ CD38⁺ (CD38⁺) cells were determined on day 9.

⁴IgG and IgM secretion from day 14–15 was measured by enzyme-linked immunosorbent assay (ELISA).