Glycodelin, also known as placental protein 14 (PP14) or progesterone-associated endometrial protein (PAEP), is a human glycoprotein with potent immunosuppressive and contraceptive activities. In this paper we report the first characterization of glycodelin-derived oligosaccharides. Using strategies based upon fast atom bombardment and electrospray mass spectrometry we have established that glycodelin is glycosylated at Asn-28 and Asn-63. The Asn-28 site carries high mannose, hybrid and complex-type structures, whereas the second site is exclusively occupied by complex-type glycans. The major non-reducing epitopes in the complextype glycans are: Gal␤1-4GlcNAc (lacNAc), GalNAc␤1-4GlcNAc (lacdiNAc), NeuAc␣2-6Gal␤1-4GlcNAc (sialylated lacNAc), NeuAc␣2-6GalNAc␤1-4GlcNAc (sialylated lacdiNAc), Gal␤1-4(Fuc␣1-3)GlcNAc (Lewis x ), and GalNAc␤1-4(Fuc␣1-3)GlcNAc (lacdiNAc analogue of Lewis x ). It is possible that the oligosaccharides bearing sialylated lacNAc or lacdiNAc antennae may manifest immunosuppressive effects by specifically blocking adhesive and activation-related events mediated by CD22, the human B cell associated receptor. Oligosaccharides with fucosylated lacdiNAc antennae have previously been shown to potently block selectin-mediated adhesions and may perform the same function in glycodelin. The potent inhibitory effect of glycodelin on initial human sperm-zona pellucida binding is consistent with our previous suggestion that this cell adhesion event requires a selectin-like adhesion process. This result also raises the possibility that a convergence between immune and gamete recognition processes may have occurred in the types of carbohydrate ligands recognized in the human.

We have recently demonstrated that a human amniotic fluid-derived glycoprotein, glycodelin-A (GdA; previously known as PP14 or PAEP), potently inhibits gamete binding in an established sperm-egg binding system and expresses immunosuppressive activities directed against a variety of different immune cell types. GdA has high mannose-, hybrid-, and complex-type biantennary oligosaccharides including structures with fucosylated or sialylated N,N-diacetyllactosediamine (GalNAc␤1-4GlcNAc) sequences, which are rare in other human glycoproteins. We now report the characterization of glycodelin-S (GdS). This is a human seminal plasma glycoprotein that is immunologically indistinguishable from GdA, but unlike the latter, does not inhibit human sperm-zona pellucida binding under hemizona assay conditions. Analysis of the N-glycans of GdS by mass spectrometry revealed that all glycoforms of GdS are different from those of GdA. GdS glycans are unusually fucose-rich, and the major complex-type structures are biantennary glycans with Lewis x (Gal␤1-4(Fuc␣1-3)GlcNAc) and Lewis y (Fuc␣1-2Gal␤1-4 (Fuc␣1-3)GlcNAc) antennae. It is probable that these highly fucosylated epitopes contribute to the immunosuppressive activity of human seminal plasma and to the low immunogenicity of sperm. This study provides the first evidence for gender-specific glycosylation that may serve to regulate key processes involved in human reproduction.

The current accepted model for high-molecular-weight gastric mucins of the MUC family is that they adopt a polydisperse coil conformation in bulk solutions. We develop this model using well-characterized highly purified porcine gastric mucin Orthana that is genetically close to the human MUC6 type. It has short side chains and low levels of sialic acid residues and includes minute amounts of cysteine residues that, if abundant, can be responsible for the self-polymerization of mucin. We have established that the mucin structure in bulk solutions corresponds to a daisy-chain random coil. Dynamic light scattering experiments probe the internal dynamics of globular subunits (individual daisies) at the approximately 9 nm length scale, whereas viscosity and light scattering measurements indicate that the size of the whole mucin chains is much larger, approximately 50 nm. The bulk viscosity (eta) scales with mucin concentration (c) in a manner similar to that found for short-side-chain synthetic comb polyelectrolytes and is characterized by a transition between semidilute (eta approximately c1/2) and entangled (eta approximately c3/2) regimes.

CA125 is a mucin commonly employed as a diagnostic marker for epithelial ovarian cancer. Induction of humoral responses to CA125 leads to increased survival times in patients with this form of cancer, suggesting a potential role for this mucin in tumor progression. In this study, oligosaccharides linked to CA125 derived from the human ovarian tumor cell line OVCAR-3 were subjected to rigorous biophysical analysis. Sequencing of the Oglycans indicates the presence of both core type 1 and type 2 glycans. An unusual feature is the expression of branched core 1 antennae in the core type 2 glycans. CA125 is also N-glycosylated, expressing primarily high mannose and complex bisecting type N-linked glycans. High mannose type glycans include Man 5 -Man 9 GlcNAc 2 . The predominant N-glycans are the biantennary, triantennary, and tetraantennary bisecting type oligosaccharides. Remarkably, the N-glycosylation profiles of CA125 and the envelope glycoprotein gp120 (derived from H9 lymphoblastoid cells chronically infected with HIV-1) are very similar. The CA125-associated N-glycans have also recently been implicated in crucial recognition events involved in both the innate and adaptive arms of the cell-mediated immune response. CA125 may therefore induce specific immunomodulatory effects by employing its carbohydrate sequences as functional groups, thereby promoting tumor progression. Immunotherapy directed against CA125 may attenuate these immunosuppressive effects, leading to the prolonged survival of patients with this extremely serious form of cancer.