CD43 (sialophorin, leukosialin) is a heavily sialylated surface protein expressed on most leukocytes and platelets including T cells. Although CD43 antigen is known to have multiple and complex structure, exact function of CD43 in each cell type is not completely understood. Here we evaluated the role of CD43 in Fas (CD95)-induced cell death in human T lymphoblastoid cell line, Jurkat. Crosslinking CD43 antigen by K06 mAb increased the Fas-mediated Jurkat cell apoptosis and the augmentation was inhibited by treatment with caspase inhibitors. Further, CD43 signaling of Jurkat cells induced Fas oligomerization on the cell surfaces implying that CD43 ligation have effects on early stage of Fas-induced T cell death. These also suggest that CD43 might play an important role in contraction of the immune response by promotion of Fas-induced apoptosis in human T cells.
Receptor Aggregation/immunology ; Jurkat Cells ; Humans ; Caspases/metabolism ; Apoptosis/*immunology ; Antigens, Surface/metabolism ; Antigens, CD95/metabolism/*physiology ; Antigens, CD43/metabolism/*physiology ; Antibodies, Monoclonal/metabolism

We studied the aggregation of a recombinant engineering antibody (chA21). Anti-ErbB2 antibody chA21 was produced by fusing single-chain Fv (scFv) with human IgG1 Fc fragment, and it was proved to be a drug candidate for cancer therapy. We characterized the aggregation of chA21 by high performance sized-exclusive chromatography (HPSEC), dynamic light scattering (DLS), SDS-PAGE, indirect ELISA assay, and compared the influence of temperature and additive on the level of aggregation and binding activity. Conformation changes of different levels of aggregation were also analyzed via circular dichroism (CD). Finally, we analyzed which part of chA21 was involved in aggregation by cleaving it into scFv and Fc fragments. The results showed that chA21 could form aggregates in the storage solution. The aggregates interacted through non-covalent bonds and remained binding activity. Temperature and additive could slightly affect the level of aggregation and binding activity, while the conformations of chA21 were stable. Aggregation propensity of scFv fragment was almost same as chA21, indicating that scFv may be the major part to form the aggregates. The research on aggregation may be helpful to develop a suitable formulation for chA21 clinical application as well as provide direction for future antibody design and reconstruction.
Antibodies ; chemistry ; metabolism ; Humans ; Immunoglobulin Fc Fragments ; chemistry ; metabolism ; Immunoglobulin Variable Region ; chemistry ; metabolism ; Protein Conformation ; Protein Engineering ; methods ; Receptor Aggregation ; immunology ; Receptor, ErbB-2 ; chemistry ; immunology ; Recombinant Proteins ; biosynthesis ; chemistry ; genetics ; immunology

OBJECTIVEThe study was designed to investigate the changes in CD(69), CD(25) and HLA-DR expressions in peripheral blood T cell in Kawasaki disease (KD).

METHODSThe authors detected CD(69), CD(25) and HLA-DR expressions in peripheral blood T cell by using flow cytometry. The patients who met the diagnostic criteria for KD comprised sixteen boys and fifteen girls (4 - 60 months of age; mean, 26 +/- 18 months). All received intravenous gammaglobulin at a dose of 1 g/(kg.d), for 2 days and oral aspirin at a dose of 30 - 50 mg/(kg.d). In case of persistent fever, a repeated dose of intravenous gammaglobulin or I.V. methylprednisolone at a dose of 20 mg/(kg.d) for three daily doses was attempted. The authors tested blood samples from 17 healthy controls consisting of nine boys and eight girls (3 - 84 months of age; mean, 25 +/- 18 months) and the samples from 31 patients.

RESULTSThe percentage of peripheral blood CD(3)(+) T lymphocyte was (54.4 +/- 9.0)% in acute stage of KD and (65.0 +/- 7.0)% in healthy controls. There was a significant difference between the two groups (P < 0.001). The values of CD(69)(+) [(11.2 +/- 12.6)%, vs. (0.6 +/- 0.4)%], CD(25)(+) [(9.2 +/- 3.5)% vs. (3.9 +/- 1.8)%] and HLA-DR(+) [(8.3 +/- 5.0)% vs. (4.3 +/- 2.3)%] in KD patients were markedly increased compared to those of the healthy controls. After intravenous gammaglobulin treatment, the percentage of CD(3)(+)CD(69)(+) and CD(3)(+)CD(25)(+) significantly decreased [CD(3)(+)CD(69)(+): (14.0 +/- 13.0)% vs. (1.6 +/- 1.2)%, P < 0.05; CD(3)(+)CD(25)(+): (7.8 +/- 4.1)% vs. (2.0 +/- 0.6)%, P < 0.01]. However, the CD(3)(+) T lymphocytes increased [(50.8 +/- 5.0)% vs. (64.9 +/- 5.5)%, P < 0.01]. There was no significant difference in expression of CD(3)(+) T lymphocyte cell activating markers between coronary artery disease group and normal coronary artery group in KD cases (P > 0.05).

CONCLUSIONCD(3)(+) T cell activation in the early and middle stages is involved in the mechanism responsible for cardiovascular injury.

Antigens, CD ; blood ; Antigens, Differentiation, T-Lymphocyte ; blood ; Aspirin ; administration & dosage ; therapeutic use ; Biomarkers ; blood ; Child, Preschool ; Dose-Response Relationship, Drug ; Drug Therapy, Combination ; Female ; Flow Cytometry ; Glucocorticoids ; therapeutic use ; HLA-DR Antigens ; blood ; Humans ; Immunoglobulins, Intravenous ; therapeutic use ; Immunologic Factors ; therapeutic use ; Infant ; Interleukin-2 Receptor alpha Subunit ; blood ; Lectins, C-Type ; blood ; Male ; Methylprednisolone ; therapeutic use ; Mucocutaneous Lymph Node Syndrome ; blood ; diagnosis ; drug therapy ; immunology ; Platelet Aggregation Inhibitors ; therapeutic use ; Prognosis ; T-Lymphocytes ; drug effects ; immunology ; Treatment Outcome