Macrophage-lymphocyte association in in vitro mouse spleen cultures; the formation of B-cell colonies.

Colonies of predominantly B lymphocytes have been grown in liquid culture, without agar or specific mitogen treatment. An essential component of the colonies is a macrophage-like cell. Colonies appear to result from continued growth of B lymphocytes following a primary macrophage-lymphocyte association which frequently occurs under a variety of culture conditions. Factors promoting colony growth are foetal calf serum and 2 mercapto-ethanol, the latter acting in part through reduction of a non-dialysable sulphur-containing component of serum.