CD40LG and cancer: In a parallel testing of several anti-TF Ab isotypes (IgG, IgM, IgA, and a pool of all isotypes) only IgM showed a clear trend to a lower level in cancer (n = 36) compared to healthy donors (0.22 ± 0.07 (SD) and 0.31 ± 0.2, resp., P = 0.08) and a significant decrease compared to the benign group (0.37 ± 0.12, n = 15, P < 0.001).