An influenza virus matrix protein‐specific human T cell line with helper activity for in vitro anti‐hemagglutinin antibody production

Abstract

A human helper T cell line (F14m) activated by the matrix protein purified from A/X31 influenza virus has been developed. After activation by antigen for 7 days, and reculture with matrix protein and irradiated autologous feeder cells, the cells obtained from an in vivo influenza virus‐immunized donor have been growing in the presence of interleukin 2 for more than 7 months. The cells all belong to the helper‐inducer T cell subset and most of them express surface membrane HLA‐DR antigens. A small number (approximately 10³) of F14m T cells provided optimal help for 1 × 10⁵ autologous T‐depleted lymphocytes for production of anti‐A/X31 but not anti‐B/HK antibodies. The F14m T cells produce soluble factors (S14m) able to help B cells to secrete anti‐A/×31 antibodies. F14m and S14m were shown to help antibody production to hemagglutinin when cultured with B cells and the whole virus. The specificity of the T cell line for type‐A matrix protein was confirmed by the ability of S14m to provide help for anti‐A/JAP (A/H2/N2) but not for anti‐B/HK antibody production. These data provide evidence for matrix protein‐specific T helper cells and factors able to provide help for antibody production against hemagglutinin, a distinct protein of the same virus.