Abstract
We recently reported the presence of C1q-binding substances in serum of a patient with CLL and circulating antigen-antibody complexes (Day et al., Clin. Res. 23:410a, 1975). We have extended this observation to study of patients' sera with various forms of malignancies and with genetically inherited C deficiencies (c1r, C2, and C3). Two methods are used: one by a modified agar diffusion (Agnello et al., Immunology 19:909, 1970) and two, by the C1q deviation test (Bokisch et al., Clin. Res. 23:409a, 1975). The modified agar diffusion test correlated with C1q levels determined by the Mancini technique (normal: 17 to 23.5 µg/ml). Fifteen of 50 malignant sera (2/3 breast, 2/2 melanoma, 5/12 acute myelogenous leukemia, 1/1 chronic lymphatic leukemia, 1/1 oat cell, 2/3 esophagus, 1/5 rectal, 1/5 ovary, 1/1 bone) wath low levels of C1q (<10 µg/ml) were strongly positive by the precipitation test. These low sera also showed high C1q-binding activity in the C1q deviation test.
