Conjugates between P815 and NK cells. Purified FITC-labeled activated NK cells were coated with MoAb of the indicated specificity, washed, and mixed with P815 cells at a ratio of 1 NK cell to 1.5 P815. The cells were pelletted, incubated for 1 hour at room temperature, resuspended, and analyzed for light scatter and green fluorescence. Conjugates were detected as FITC⁺ particles with side scatter greater or equal to that of P815 cells.