CD4 and breast angiosarcoma: Figure 3 illustrates how the probability of developing BA increases (i) as the percentage of double-positive cells among CD19+CD5+ B cells decreases below 20% (and especially below 10%), (ii) as the number of TNFR1 molecules on CD8+CD45RA+ cells decreases below 1000 receptors per cell, and (iii) as the number of TNFR1 molecules on CD4+ cells increases above 600 to 800 receptors per cell.