The human blood-group MM and NN antigens carry 2 to 4 immunodominant groupings per repeating subunit and differ only by one sialic acid residue per immunodominant group. This residue covers in the MM antigen the beta-D-galactopyranosyl group that is terminal in the N immunodominant structure and that, together with a terminal alpha-linked N-acetylneuraminic acid residue, is responsible for N specificity. M specificity was readily converted into N specificity by mild acid treatment. N structure is the immediate biochemical precursor of M structure, and M and N antigenic specificities are not determined by two allelic genes as believed hitherto. The NN antigen was inactivated by beta-D-galactosidase as well as by removal of N-acetylneuraminic acid. Some of the reactivities of the NN antigen, lost upon beta-D-galactosidase treatment, reappeared on subsequent partial N-acetylneuraminic acid removal. The structure uncovered by complete sialic acid depletion of MN antigens is the Thomsen-Friedenreich T antigen, the specificity of which is determined by beta-D-galactopyranosyl groups. Beta-D-Galactosidase treatment transformed the T antigen into one possessing Tnactivity. The significance of blood-group MN active substances extends to human breast cancer, where MN antigens were found in benign and malignant glands, but some of their precursors in cancerous tissue only.

ABO Blood-Group System↗

PubMed1975

Endotoxin-binding substances from human leukocytes and platelets.

We have found whole human platelets, granulocytes, and mononuclear leukocytes to possess high affinity for the toxic lipopolysaccharide from all gram-negative bacteria tested. We have extracted these cells and platelets with n-butanol-water; all endotoxin-binding activity resided in the organic phase. These endotoxin-binding extracts did not block serologically active groupings on endotoxins or receptors on the erythrocytes. The specificity of these still crude materials was less that that of the highly purified erythrocyte lipopolysaccharide receptor previously described by us, since they bound some bacterial antigens not related to endotoxins. Depending on source, the n-butanol extracts contained 40 to 52% glycerophosphatides (most active), 15 to 22% sphingomyelin, 17% cholesterol, less than 2 to 5% triglycerides, and 7 to 13% inactive peptide. The most active substances in the n-butanol extract were soluble in petroleum ether, whereas the peptide and sphingomyelin were not. Thus, no constituent protein, carbohydrate, or nucleic acid was present in the most highly active material. Polyacrylamide gel electrophoresis of the petroleum ether-soluble material showed for each extract one lipid band only, which was well defined and migrated similarly to phosphatidyllipids. Because of the lipidic nature of the inhibitory substances from leukocytes and platelets we also tested the lipid A component of bacterial endotoxins and some of its derivatives. Lipid A inhibited endotoxin coating of erythrocytes. De-O-acylation of lipid A left amide-linked 3-D-hydroxymyristic acid intact and increased the inhibitory activity of lipid A 20-fold. Complete de-O- and de-N-acylation destroyed its inhibitory effect.

Antigens, Bacterial↗

PubMed1975

Effect of carbamylation of lysine epsilon-amino groups on the activity of blood group specific glycoproteins.

Carbamylation of epsilon-amino groups of lysine of human blood group MM glycoprotein, some of its precursors and the blood group A B antigens gave products with 41% - 91% epsilon-amino group substitution. Even the most extensive carbamylation led to only marginal changes in the circular dichroic (CD) spectra of these substances and none in sedimentation coefficients studied. Nevertheless, carbamylation resulted in either increased or unchanged or decreased inhibitory activity of all blood group antigens tested depending solely on the source of the hemagglutinin used. Carbamylation of epsilon-amino groups of these blood group glycoproteins therefore leads to minor conformational changes, not involved with the primary blood group specificity, which is recognized by a large proportion but not by all corresponding antibodies and lectins.

ABO Blood-Group System↗

PubMed1975

Infectious mononucleosis: immunization-identification.

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Adult↗

PubMed1975

Specific inhibition of HL-A alloantisera by various carbohydrate-containing macromolecules.

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Animals↗

PubMed1975

Blood group MN antigens and precursors in normal and malignant human breast glandular tissue.

Blood group M and N active substances were demonstrated in human mammary gland tissue in both benign and malignant lesions. The precursor T (Thomsen-Friedenreich) antigen occurred only in cancerous tissue, where it was found regularly in the 15 gross cancers tested. The precursor Tn antigen also was found regularly in cancerous breast tissue; Both antigens were reactive in breasts with in situ carcinoma. The T antigen was not demonstrable in the 6 benign mammary glands studied; similarly, the Tn antigen was unmasked by sialidase treatment of healthy breast tissues. Anti-T antibody, present in all human sera, was severely depressed in many breast cancer patients compared to controls.

Adenocarcinoma↗

PubMed1974