To determine whether ADCC is also affected by irradiation, a B-cell lymphoma line (Daudi-β2M) transfected to express β2-microglobulin to increase expression of inhibitory class I HLA (22) was treated with a single dose of 8 Gy, cultured for 72 h, opsonized with an anti-CD20 antibody, rituximab, and then incubated with NK cells. Here, B2M is linked to B-cell non-Hodgkin lymphoma.