Surface of human sperm bears three differently charged CD52 forms, two of which remain stably bound to sperm after capacitation

Abstract

gp20 is a sialoglycoprotein of the human sperm surface with a core peptide homologous to the leukocyte antigen CD52, a GPI-anchored glycosylated protein which is described by the monoclonal antibody CAMPATH-1. Comparative analyses, by means of CAMPATH and anti-gp20, indicated that they describe it in morphologically and functionally different ways, suggesting that the respective epitopes are different but also casting doubt on the immunological identity of the antigen. In the present study, we used immunodepletion to demonstrate that CAMPATH and anti-gp20 interact with the same antigen, but that anti-gp20 has a much higher avidity for the antigen than CAMPATH. Anion exchange fractionation analysis of the antigen revealed three differently charged gp20-CD52 forms, the least charged of which, was largely without a GPI-anchor. All three forms were associated with freshly ejaculated sperm, whereas capacitated sperm only contained the two GPI-anchored, more charged forms, which were also the ones found in the prostasome fraction of seminal plasma and in leukocytes. The two charged, GPI-anchored forms were described as homogeneous by anti-gp20, since they ran as a singlet; the third form ran as a doublet. When tested for insertion into Jurkat T cells, the medium charged form inserted the most readily and the less charged one could not be inserted at all.

A novel reduced-intensity stem cell transplant regimen for nonmalignant disorders

“…Human sperm has CD52 expression and is capable of binding the drug. 29 Germ cell and Leydig cell damage has been described in adult recipients of Campath-1H (with fludarabine and melphalan) in a similar manner to myeloablative therapies. …”

Retention of membrane charge attributes by cryopreserved-thawed sperm and zeta selection

“…Changes in protein composition in the membrane have been documented, for instance, a decrease in membrane P34H and an increase in alphatubulin after cryopreservation [20]. The mechanism involved in the zeta selection of sperm with strict normal morphology was based on the greater net negative charge of mature sperm due to membrane sialoglycoproteins [21,22], specifically, gp20-CD52 glycopolypeptides, acquired during transit through the epididymis [23]. Researchers have correlated the maturity of sperm membranes with strict normal morphology, an parameter indicative of successful fertilization [7,24,25].…”

“…Moreover, sperm selection by high-magnification motile sperm organelle morphology examination (MSOME) [29], electrophoresis [30] and hyaluronic acid hydrogel have recently been proposed [31]. While the zeta method has shortcomings such as low sperm recovery, a requirement of uncapacitated sperm [16,17] and the possible bias for X-bearing sperm [9,21,32,33], nevertheless, the zeta method appears promising for selecting thawed sperm for ICSI. However, more studies are needed before its application in routine ART treatment.…”

“…One portion was cryopreserved as outlined below while the remaining portion was subjected to zeta processing. Zeta processing [1] was carried out immediately to avoid confounding factors due to capacitation-related changes in the sperm membrane electropotential [16,17]. The washed sperm from each specimen was pipetted into a new centrifuge tube and diluted with 5 ml of serum-free HEPES-HTF medium.…”

Expression of gp20, a human sperm antigen of epididymal origin, is reduced in spermatozoa from subfertile men

“…It has also been suggested that an O-glycan (Valentin et al, 1992;Diekman et al, 1999;Hasegawa et al, 2003) is part of this intriguing antigen. CD52 is described in different ways by differently raised antibodies (Focarelli et al, 1999;Della Giovanpaola et al, 2001;Yeung et al, 2001) so that each antibody seems to be directed against a different epitope of the antigen and different epitopes are probably related to different and differently located CD52 forms. For example, S-19, an IgG monoclonal antibody raised in mice injecting human sperm extracts is probably directed against N-glycans specific of reproductive system and it does not recognize any component of the immune system .…”