1. Lafferty, K. J., Misko, I. S. & Cooley, M. A. Nature 249, 275–276 (1974).
2. Wagner, H., Feldmann, M., Boyle, W. & Schrader, J. W. J. exp. Med. 136, 331–343 (1972).
3. MacDonald, H. R., Phillips, R. A. & Miller, R. G. J. Immun. 111, 575–589 (1973).
4. Pilarski, L. M. J. exp. Med. 145, 709–725 (1977).
5. Paetkau, V. in Molecular Mediators of Cellular Immunity (eds Hadden, J. W. & Stewart, W. E. II) (Humana, Clifton, in the press).