Alpha 2,3-specific desialylation of human red cells: effect on the autoantigens of the Pr, Sa and Sia-l1, -b1, -lb1 series.

BACKGROUND AND OBJECTIVES

Pr1,2,3, PrM, Sa and Sia-l1, -b1, -lb1 are sialic acid (NeuNAc)-dependent antigens recognized by human cold agglutinins. Pr and Sa antigens are the O-glycans of glycophorins containing alpha 2,3NeuNAc (to galactose) and/or alpha 2,6NeuNAc (to galactosamine). The antigens of the Sia-l1, -b1, -lb1 complex are gangliosides that may carry alpha 2,3NeuNAc (to galactose) and/or alpha 2,8NeuNAc (to NeuNAc). We studied the NeuNAc groups involved in the antigens.

MATERIALS AND METHODS

From 74 sera with cold agglutinins against NeuNAc-dependent antigens, anti-T-free preparations were made and tested against human red cells, treated with an alpha 2,3-specific recombinant sialidase.

RESULTS

Most (51/62) Pr antigens use alpha 2,3NeuNAc, some (8/62) use alpha 2,6NeuNAc and a few (3/62) use both sialyl groups as immunodominant components on glycophorins. The immunodominant component of Sa and Sia-l1, -b1, -lb1 determinants was alpha 2,3NeuNAc in all cases.

CONCLUSION

The red cell target structures for cold agglutinins against NeuNAc-dependent antigens have been identified. We propose a Pr nomenclature to reflect this. The binding of anti-Pr to gangliosides may be the basis for anti-Pr-induced peripheral neuropathy.