The CBF.78 monoclonal antibody to human sialophorin has distinct properties giving new insights into the CD43 marker and its activation pathway

Abstract

We confirm here the CD43 specificity of the CBF.78 monoclonal antibody (mAb) and compare its phenotypic and functional capacities to classical group-A mAbs (DFT1, MEM-59) and to 2 other CD43 mAbs (RDP/AD9, 161-46). It reacts with stable human CD43 transfectants in a sialic acid independent way and blocks completely cell binding of RDP/AD9 or 161-46 more or less but not DFT1 and MEM-59. Its distribution differs from all other CD43. B lymphocytes, but surprisingly the majority of granulocytes or monocytes are CBF.78 negative. CBF.78 is expressed on all T lymphocytes, but the number of CBF.78 molecules/cell is low and equally represented on resting T CD4 and CD8 cells. In comparison to naive T lymphocytes, CD45RO cells increase their CBF.78 epitopes much more than other CD43 epitopes. At a single cell level, confocal microscopy shows that CBF.78 can exist independently of other epitopes. CBF.78 is able to induce homotypic adhesion in different cell lines but not in peripheral blood lymphocytes and is unable to relocalise the targeted molecules. U937 cell line that is not agglutinated by CBF.78 (or RDP/AD9) undergoes a stronger adhesion with PMA, when this reagent is combined with this mAb. By itself CBF.78 is unable to activate T lymphocytes and to costimulate CD3 mAbs but partially blocks PMA. The phosphorylation of the tyrosine kinase p59fyn and p56lck, driven by CBF.78, is weak and almost blocked by PMA. Altogether these data support the hypothesis that there are at least 3 modes of interaction between PKC and CD43 pathways: each pathway is inhibitory towards the other but the CD43 one can also be synergistic.

Expression Characteristics and Stimulatory Functions of CD43 in Human CD4+ Memory T Cells: Analysis Using a Monoclonal Antibody to CD43 That Has a Novel Lineage Specificity

“…There are previous reports indicating that CD43 molecules may also have accessory involvements in T cell activation, such as, for example, in mice, where CD43 mAb appears to costimulate T cell activation during treatment with plastic-bound CD3 mAb and alloantigens (17,40). In humans, however, there does not appear to be any evidence of CD43 mAb being involved in a costimulatory capacity in the polyclonal activation of T cells (41). In situations involving Ag-specific responses, there is one report that CD43 is necessary for the production of IL-2 in HLA class II-specific human hybridoma T cells (42), but it is important to note that the experimental system used to obtain these data was an unusually artificial one.…”

Regulation of CD43-induced U937 homotypic aggregation

“…However, when the data reported here are considered in more detail, this view does not seem to be correct. The CD43 mAbs, which do induce aggregation (161-46, HI161, MEM-59, and 84-3C1), all recognize the 110-kDa isoform [30]. Some of the mAbs (e.g., 148-1C3 and RPD/AD9) that recognize neuraminidase-sensitive epitopes, the most negatively charge portions of CD43, did not induce homotypic clustering.…”

“…Since previous studies have identified tyrosine phosphorylation as a downstream event in CD43-induced signaling [29,30,36], the next experiments explored this question. The results are shown in Fig.…”

Production and the characterization of monoclonal antibody against CD43, K06

“…(18). In fact, it has been reported that many of the anti-CD43 monoclonal antibodies can recognize glycosylated fraction of CD43 molecule (4,6,13,14,19,20).…”