Selective expansion of memory CD4⁺ T cells by mitogenic human CD28 generates inflammatory cytokines and regulatory T cells

• Published in: European journal of immunology 2008-06, Vol.38 (6), p.1522-1532
• Main Authors: Singh, Manisha, Basu, Sreemanti, Camell, Christina, Couturier, Jacob, Nudelman, Rodolfo J, Medina, Miguel A, Rodgers, John R, Lewis, Dorothy E
• Format: Article
• Language: English
• Subjects: Adult; Androstadienes - pharmacology; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - pharmacology; CD28 Antigens - immunology; CD4-Positive T-Lymphocytes - drug effects; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - metabolism; Cell Differentiation - drug effects; Cell Differentiation - immunology; Cell Proliferation - drug effects; Coculture Techniques; Costimulation; Cytokines - metabolism; Enzyme Inhibitors - pharmacology; Forkhead Transcription Factors - analysis; Human T cells; Humans; Immunoglobulin Fab Fragments - immunology; Immunoglobulin Fab Fragments - pharmacology; Inflammation; Interleukin-2 Receptor alpha Subunit - analysis; Leukocyte Common Antigens - analysis; Leukocytes, Mononuclear - drug effects; Leukocytes, Mononuclear - immunology; Leukocytes, Mononuclear - metabolism; Lymphocyte Activation - drug effects; Phosphodiesterase Inhibitors - pharmacology; Phosphoinositide-3 Kinase Inhibitors; Regulatory T cells; Signal Transduction - drug effects; T cell activation; T-Lymphocyte Subsets - drug effects; T-Lymphocyte Subsets - immunology; T-Lymphocyte Subsets - metabolism; T-Lymphocytes - drug effects; T-Lymphocytes - immunology; T-Lymphocytes - metabolism; T-Lymphocytes, Regulatory - cytology; T-Lymphocytes, Regulatory - drug effects; T-Lymphocytes, Regulatory - immunology; Wortmannin
• ISSN: 0014-2980; 1521-4141
• DOI: 10.1002/eji.200737929

Costimulatory signals are important for development of effector and regulatory T cells. In this case, CD28 signaling is usually considered inert in the absence of signaling through the TCR. By contrast, mitogenic rat CD28 mAb reportedly expand regulatory T cells without TCR stimulation. We found that a commercially available human CD28 mAb (ANC28) stimulated PBMC without TCR co-ligation or cross-linking; ANC28 selectively expanded CD4⁺CD25⁺FOXP3⁻ (Teff) and CD4⁺CD25⁺FOXP3⁺ (Treg) cells. ANC28 stimulated the CD45RO⁺ CD4⁺ (memory) population, whereas CD45RA⁺CD4⁺ (naive) cells did not respond. ANC28 also induced inflammatory cytokines. Treg induced by ANC28 retain the Treg phenotype longer than costimulated Treg. Treg induced by ANC28 suppressed CD25⁻ T cells through a contact-dependent mechanism. Purity influenced the response of CD4⁺CD25⁺ cells because bead-purified CD4⁺CD25⁺ cells (85-90% pure) responded strongly to ANC28, whereas 98% pure FACS-sorted CD4⁺CD25bright (Treg) did not respond. Purified CD4⁺CD25int cells responded similarly to the bead-purified CD4⁺CD25⁺ cells. Thus, pre-activated CD4⁺ T cells (CD25int) respond to ANC28 rather than Treg (CD25bright). The ability of ANC28 to expand both effectors producing inflammatory cytokines as well as suppressive regulatory T cells might be useful for ex vivo expansion of therapeutic T cells.