On the Stability of T Cell Differentiation Antigens

The discovery of T cell differentiation antigens has undoubtedly represented one of the major advances in cellular immunology during the past 10 years. The recent availability of monoclonal antibodies has further strengthened the discriminating potency of the anti-T cell antibodies. Thus, a T cell may beyond any uncertainty be defined by its capacity to bind an anti-Thy 1 antibody in the mouse or OKT1, OKT3, or Leu 1 antibodies in man. Similarly, convergent arguments have been accumulated to separate peripheral T cells into two distinct subsets with distinct functions (helper/inducer on the one hand, cytotoxic/suppressor on the other hand) that probably recognize different antigens (class IIantigens for the former, class I antigens for the latter). It is not my aim to question these major advances which will be emphasized and developed in many aspects during this meeting. I would rather call attention to several difficulties inherent in the biology of differentiation antigens that should be kept in mind when using these antigens as cell markers, as is currently done.