Fig. 4.

Sulfated GAGs mediate the binding of properdin to apoptotic T cells. (a) Wild-type, GAG-deficient, and HS-deficient CHO cells were incubated with purified properdin and bound properdin measured via FACS. (b) Wild-type CHO cells were cultured in chlorate-containing media to prevent sulfation of GAGs and then analyzed for their ability to bind properdin. The addition of sodium sulfate (SO₄) reversed the inhibitory effect of chlorate on GAG sulfation. (c) Apoptotic T cells were preincubated at 20 μg/ml in buffer/media with heparin (predominantly alternating IdoA2S-GlnNS6S), HS (an undersulfated form of heparin), CS-A (chondroitin sulfate-A; GlcA-GalNAc4S), CS-B (dermatan sulfate; IdoA-GalNAc), CS-C (GlcA-GalNAc6S), CS-D (GlcA2S-GalNAc6S), or CS-E (GlcA-GalNAc4, 6S). Purified properdin was then added to all samples, and properdin deposition on the T cell surface was assessed. (d) T cells were activated in normal media or media containing chlorate or chlorate and SO₄, and deposition of purified properdin was measured after apoptosis induction. All values shown are the mean ± SD values derived from a minimum of three separate experiments.