Human lymphocyte production of immunoreactive thyrotropin

Area of Science:

• Immunology
• Endocrinology
• Molecular Biology

Background:

• Previous studies indicated interferon-alpha inducers stimulate human lymphocyte production of a corticotropin (ACTH)-like peptide.
• Thyrotropin (TSH) was not observed in human lymphocytes under those specific conditions.

Purpose of the Study:

• To investigate whether human lymphocytes can produce TSH in response to different stimuli.
• To characterize the nature and molecular properties of any TSH-like substance produced by lymphocytes.

Main Methods:

• Stimulation of human lymphocytes with staphylococcal enterotoxin A (a T-cell mitogen).
• Detection and quantification of immunoreactive (ir) TSH.
• Biochemical characterization using NaDodSO4/polyacrylamide gel electrophoresis, gel filtration chromatography, and concanavalin A affinity chromatography.
• Radiolabeling of lymphocyte-derived ir TSH for molecular analysis.

Main Results:

• Staphylococcal enterotoxin A induced human lymphocyte production of an immunoreactive (ir) TSH, unlike interferon-alpha inducers.
• Lymphocyte synthesis of ir TSH showed a time-dependent pattern, detectable at 24 hr, peaking at 48 hr.
• Electrophoresis and chromatography revealed ir TSH composed of subunits similar to human TSH alpha and beta chains, with molecular masses of 80, 50, 26, 14, and 12 kilodaltons.
• The ir TSH demonstrated glycoprotein properties, binding to concanavalin A.

Conclusions:

• Human lymphocytes can produce a TSH-like substance in response to T-cell mitogens.
• This TSH-like substance shares biochemical characteristics with native human TSH, including subunit composition and glycoprotein nature.
• These findings suggest lymphocytes possess the capability to synthesize multiple pituitary hormone-like peptides, including both ACTH and TSH.