TABLE 1.

DT-specific proliferation of human PBLs in vitro^a

Group	DT stimulation	[3H]thymidine uptake (cpm)b
PBLs	−	1,908 ± 87
	+	6,981 ± 454
PBLs plus rhPRL	−	1,829 ± 128
	+	11,170 ± 528*

^aHuman PBLs were obtained from healthy donors, and the cell suspension was used for a DT-specific proliferation assay in vitro. DT (10 ng/ml) and lymphocytes (5 × 10⁶/200 μl/well) were added to flat-bottomed 96-well plates (Costar). Five days later, proliferation was assayed by pulsing cells with 1 mCi (3.7 × 10⁴ becquerels) of [³H]thymidine (6.7 Ci/mmol; New England Nuclear, Boston, MA) for 8 h and harvesting them with a MASH II apparatus (Microbiological Associates, Bethesda, MD). Student's t test was performed to determine statistical differences.

^bData are means ± SD. *, P < 0.01, comparing the PBL-plus-hPRL group with the PBL group for responses to DT stimulation.