Cell lines derived from human autorosette-forming cells with suppressive activity.

Area of Science:

• Immunology
• Cell Biology

Background:

• T lymphocytes play a crucial role in immune responses.
• Immune disorders can arise from dysregulation of T cell activity.
• Autorosette-forming cells represent a unique subpopulation of lymphocytes.

Purpose of the Study:

• To investigate the immunoregulatory properties of human T lymphocytes that form autorosettes.
• To characterize the suppressor activity of factors derived from these cells.
• To explore the relationship between this suppressor activity and interleukin-2 (IL-2).

Main Methods:

• Fractionation of T lymphocytes into rosette-forming (R) and nonrosette-forming (NR) cells based on autorosette formation.
• Culture of R and NR subpopulations and analysis of their supernatant activity.
• Assay of supernatant effects on phytohemagglutinin (PHA)-induced normal T cell proliferation and an IL-2-dependent cytotoxic T cell line (CTLL).
• Phenotypic analysis of suppressor cells and preliminary purification of the suppressor factor.

Main Results:

• Supernatants from R cell lines, particularly from patients, exhibited potent suppressor activity on T cell proliferation.
• The suppressive effect was not cytotoxic and was overcome by increasing concentrations of exogenous IL-2.
• Preincubation with IL-2 protected CTLL cells from the suppressor factor.
• Suppressor cells were identified as T cells (OKT4+, OKT8+) that predominantly formed autorosettes.

Conclusions:

• Autorosette-forming T cells produce a suppressor factor that competitively inhibits IL-2-mediated T cell proliferation.
• This suppressor factor may play a role in immune dysregulation observed in certain immune disorders.
• Further study of these suppressor cell lines can elucidate mechanisms of immunomodulation.