Anti-CD2 mAb S5.2 induces γδ–T-cell expansion from mitogen-stimulated PBMC cultures.

Cultures of human PBMC were initiated (day 0) by pre-incubating with IFN-γ (1000 U/mL) and then 24 hours later (day 1) with the addition of both OKT3 (10 ng/mL) and IL-2 (300 U/mL). The indicated anti-CD2 mAb or its corresponding isotype control antibody (5 μg/mL) was added on day 0. After 7 to 10 days, cultures were analyzed by FACS. Viable T-lymphocytes were first identified by gating on the CD3-PE⁺ and PI⁻ populations. (A) Percentage of T-lymphocytes staining with an anti-γδ-TCR–FITC mAb is shown in each histogram. Results are representative of experiments performed using materials obtained from at least 5 different persons. (B) Numbers of γδ-T cells found in cultures initiated in the presence of the indicated anti-CD2 mAbs or isotype controls (P < .02 between mAb S5.2 and IgG_2a control). Other antihuman CD2 mAbs tested—6F10.3 (mouse IgG₁), 39C1.5 (rat IgG_2a), and LT-2 (mouse IgG_2b, not shown)—do not induce γδ–T-cell expansion. Data represent absolute numbers of γδ-T cells (mean ± SD) determined in quadruplicate; experiments were performed at least 3 separate times from samples obtained from different persons.