Characterization of Lymphocyte Subsets in Cynomolgus Monkeys Using Flow Cytometry. Influence of Methylprednisolone

Abstract

The use of a nonrodent species is helpful to confirm results obtained in preclinical immunotoxicity assessment in rodents. As no specific reagents are available to study lymphocyte subsets in monkeys, the cross-staining properties of a panel of commercially available human monoclonal antibodies were studied in cynomolgus monkeys using a whole-blood technique for the separation of lymphocytes. The flow cytometry analysis showed that anti-leu-16 (B cells), anti-leu-5b (T cells), anti-leu-2a (suppressor/cytotoxic T cells), and OKT₄ (helper/inducer T cells) gave homogeneous and reproducible results in contrast to anti-leu-12 (B cells), anti-leu-4 (T cells), OKT₈ (suppressor/cytotoxic T cells), and anti-leu-3a (helper/inducer T cells). This technique allowed us to determine the lymphocyte subset profile in this species with a reversed ratio of helper/suppressor T cells as compared to humans. Finally, results obtained following a single intravenous injection of 4 mg/kg methylprednisolone confirmed the validity of this technique by showing the expected transient lymphopenia predominantly affecting helper T lymphocytes. These data provide a basis with which to evaluate lymphocyte subsets routinely and to correlate phenotype with toxic alterations in immune functions.

Key Words: :

• Lymphocytes
• Cynomolgus monkeys
• Methylprednisolone