Chemical composition and tissue distribution of the human CDw44 glycoprotein

Abstract

The CDw44 glycoprotein was purified from 2.3 x 10(11) CD3+ CD4+ CD8- T-chronic lymphocytic leukaemia (CLL) cells using F10-44-2 monoclonal antibody affinity chromatography, DEAE-Sepharose anion-exchange chromatography, passage down carboxymethyl (CM)-Sepharose cation-exchange columns, wheat germ lectin affinity chromatography and gel-permeation chromatography. On elution in non-ionic detergents from the DEAE column, two distinct peaks of antigen activity were obtained. The CDw44 glycoprotein in each peak was a glycoprotein of 85,000 MW, but the amino acid composition of the peaks was noticeably different. Carbohydrate compositions showed that each peak contained approximately 30% (w/w) carbohydrate, the composition suggesting both O-linked and complex N-linked glycans. Modulation studies with the F10-44-2 antibody on normal peripheral blood mononuclear cells (PBMC) demonstrated that the CDw44 glycoprotein of T cells consisted of one fraction that was readily modulated, and the other which was resistant to modulation. Detailed tissue distribution studies for CDw44 were performed using the F10-44-2 antibody on frozen sections of human tissues. CDw44 has a restricted tissue distribution, but is found on many highly diverse cell types (e.g. T lymphocytes, smooth muscle cells, some secretory glands, skin epithelial cells).