Immunofluorescence analysis. Expression of CD31 on Lyt2⁺-AR. CTL line (A), ConA-activated BALB/c spleen cells (B), 1934.4 hybridoma (C), PL/J spleen cells (D). Open areas are isotope control MoAb; shaded areas are reactivity of CD31 MoAb. Results are representative of 3 separate experiments.