Human B cell activating factor (BCAF): production by a human T cell tumor line

Area of Science:

• Immunology
• Cell Biology

Background:

• Previous studies identified a B Cell Activating Factor (BCAF) in T cell supernatants that activates and proliferates resting B cells.
• BCAF was distinguished from known lymphokines like IL-2 and IL-4.

Purpose of the Study:

• To describe the production of BCAF using a human T cell tumor line (T687).
• To optimize BCAF production and purification for further biochemical analysis.

Main Methods:

• Stimulation of the T687 T cell line with phorbol myristate acetate (PMA) and phytohemagglutinin (PHA).
• Separation of the stimulatory and secretory phases to obtain purified BCAF-containing supernatants.
• Analysis of supernatant contents for lymphokines (IL-2, IL-4, IFN) and lymphotoxin.

Main Results:

• The T687 cell line efficiently produces BCAF upon PMA stimulation, potentiated by PHA.
• Separating stimulation from secretion yielded supernatants free of PMA and PHA.
• These supernatants contained IL-2 (2-10 ng/ml) and traces of lymphotoxin, but not IL-4 or IFN.

Conclusions:

• The T687 cell line provides a scalable source for BCAF production.
• This system facilitates biochemical studies aimed at purifying the BCAF molecule(s).
• The findings pave the way for understanding BCAF's role in B cell activation.