Table 1.

DNA synthesis in unfractionated tonsillar B cells in response to anti-CD5 monoclonal antibodies (mAbs) after engagement of CD40 or CD40 and surface immunoglobulin M (sIgM)

		BL1a (μg/ml)			OKT1 (μg/ml)			UCHT2 (μg/ml)
Stimulus	0	0·5	5	50	0·5	5	50	0·5	5	50
Experiment 1
Control	995 ± 401	2250 ± 600	2188 ± 648	2734 ± 1106	1448 ± 230	1449 ± 465	1540 ± 548	1606 ± 877	2138 ± 218	1912 ± 523
sIgM	3021 ± 334	5005 ± 1154	5751 ± 1504	8495 ± 1824	5563 ± 1298	4068 ± 1265	4306 ± 1906	2843 ± 693	5690 ± 1862	4647 ± 1517
CD40	18 325 ± 6428	20 204 ± 2974	19 880 ± 6592	20 841 ± 2727	18 502 ± 3771	18 133 ± 4833	14 689 ± 5474	30 099 ± 4016	26 428 ± 4423	17 529 ± 6674
sIgM + CD40	40 504 ± 4364	38 464 ± 4772	36 575 ± 4836	40 931 ± 4569	42 701 ± 4367	36 709 ± 4715	26796 ± 3890	49 168 ± 5760	32 125 ± 5341	22 905 ± 4122
Experiment 2
Control	1474 ± 933	2027 ± 604	2047 ± 361	2634 ± 674	2031 ± 464	1834 ± 101	1459 ± 598	1721 ± 733	1884 ± 800	2127 ± 807
sIgM	8354 ± 2526	6374 ± 1827	7058 ± 1258	7185 ± 1096	7629 ± 1385	4995 ± 2853	2555 ± 915	3372 ± 1318	5641 ± 2198	5163 ± 1495
CD40	23 291 ± 5754	17 383 ± 1573	18 462 ± 2437	22 029 ± 4992	23 533 ± 3467	225 851 ± 5231	21 252 ± 3784	28 242 ± 5763	22 009 ± 4461	20 633 ± 5898
sIgM + CD40	40 921 ± 6836	45 891 ± 8802	43 891 ± 3656	49 934 ± 8253	39 469 ± 6212	46 012 ± 5242	28 001 ± 3558	38 852 ± 8529	37 125 ± 3242	32 997 ± 3247

B cells (10⁵ cells/well) were cultured for 3 days with: non-transfected mouse L cells (‘Control’); CD32-transfected mouse L cells and anti-IgM antibody at 0·5 µg/ml (‘sIgM’); CD40 ligand (CD40L)/CD32-transfected cells (‘CD40’); and CD40L/CD32-transfected L cells and anti-IgM antibody (‘sIgM + CD40’) in the presence or absence of CD5 mAbs. [³H]Thymidine ([³H]Tdr) incorporation was measured during the final 18 hr of culture. Values for [³H]Tdr uptake by mouse L cells alone were always less than 1000 counts per minute (c.p.m.) (results not shown).