Cell surface immunoglobulin. 3. Isolation and characterization of immunoglobulin from nonsecretory human lymphoid cells.

Cells from an established line of Burkitt lymphoma (Daudi) were enzymatically radioiodinated, and labeled Ig from the cell surface was isolated and studied. Subcellular fractionation of labeled cells confirmed that intracellular proteins from the cytoplasm are not iodinated by this method. Radioactive Ig was identified as monomeric (8S) IgM, and an average of 10(5) Ig molecules was found per cell.

Cell surface immunoglobulin. II. Isolation and characterization of immunoglobulin from mouse splenic lymphocytes.

The proteins on surfaces of living splenic lymphocytes from normal BALB/c mice were iodinated enzymatically. Such cells were fractionated into two sub-populations: one composed almost exclusively of small lymphocytes and the other mainly of large lymphocytes and plasma cells. Specific immunoprecipitation of radiolabeled surface Ig obtained from lysates of these cell populations indicated that approximately 2-3% of the acid-precipitable radioactivity from the cell surface is Ig.

A correlative study of immunological phenomena in pernicious anaemia.

Twenty patients with established pernicious anaemia have been studied by immunological techniques, in order to determine patterns of gastric antibody production. The presence of such antibodies and the immunoglobulin species in which they occur have been determined in serum, gastric juice and mononuclear inflammatory cells of the gastric mucosa. The lack of correlation found suggests that gastric antibodies in the gastric juice are not derived from serum and that serum and gastric juice antibodies are produced, regardless of immunoglobulin class, in some degree or wholly from different sites.

The immunoglobulin class of autoantibody-containing cells in the gastric mucosa.

Autoantibody to Castle's intrinsic factor in mucosal plasma cells in gastric biopsies of patients with pernicious anaemia has been shown to be of the IgG type, using a double-labelling technique. The role of IgG immunoglobulins compared with that of IgA immunoglobulins in the immune response to autoantigens and to foreign proteins in the gastrointestinal tract is discussed.

CHARACTERIZATION OF THE HUMAN GASTRIC PARIETAL CELL AUTO-ANTIGEN.

The gastric parietal cell auto-antigen is localized essentially in the microsomal fraction of mucosal homogenates obtained by centrifugation over a sucrose density gradient. The fractionation is facilitated by digestion of gastric mucus with ficin before disruption of the tissue. The antigen was assayed by a quantitative complement-fixation method.