Helper activity of T lymphocytes which have been stimulated by keyhole limpet haemocyanin <em>in vitro</em>.

Details are given of a system for keyhole limpet haemocyanin (KLH)-induced DNA synthesis by murine T lymphocytes in vitro. Lymph node T cells from mice primed with KLH and Bordetella pertussis were stimulated with KLH under the defined conditions, and it was found that such cultured cells exhibited substantial non-specific helper activity. In contrast similarly primed T cells which had not been cultured showed only antigen-specific help. it is concluded that proper account should be taken of nonspecific effects when studying the activity of antigen-specific helper cells in in vitro. [ABSTRACT FROM AUTHOR]