Biomaterial Database

Differences between the in vitro combinations of secretory component (SC) and immunoglobulin polymers (Ig) by enumeration of SC epitopes. 1984

C Geneste, and R Mangalo, and S Iscaki

The enumeration of the SC epitopes has been established on 125I-labelled free and combined SC, by binding to anti-SC coated beads, then by addition of 3H-labelled anti-SC Fab' fragments of various specificities. The number of moles of Fab' fragments found on the beads increases in relation to the introduced amount. The extrapolation to an infinite concentration of added Fab' fragments gives the maximal theoretical accessible number of SC epitopes. The number of hidden epitopes (cryptotopes) is established by subtracting the total number found on sIgA, IgA-SC and IgM-SC from those found for free SC. These values are confirmed with Fab' fragments specific for the inaccessible determinant of SC. There are 4 cryptotopes in the case of sIgA, 3 for IgA1-SC, 2 for dimer IgA-SC and only 1 for IgM-SC (polyclonal or monoclonal). Thus the in vitro combinations of SC with polyclonal IgA dimers are different from the in vitro combinations with polyclonal or monoclonal IgM. The structural implications of these differences are discussed.

UI	MeSH Term	Description	Entries
D007070	Immunoglobulin A	Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory IgA (IMMUNOGLOBULIN A, SECRETORY) is the main immunoglobulin in secretions.	IgA,IgA Antibody,IgA1,IgA2,Antibody, IgA
D007071	Immunoglobulin A, Secretory	The principle immunoglobulin in exocrine secretions such as milk, respiratory and intestinal mucin, saliva and tears. The complete molecule (around 400 kD) is composed of two four-chain units of IMMUNOGLOBULIN A, one SECRETORY COMPONENT and one J chain (IMMUNOGLOBULIN J-CHAINS).	Colostral IgA,IgA, Exocrine,IgA, Secretory,SIgA,Secretory IgA,Secretory Immunoglobulin A,Exocrine IgA,IgA, Colostral
D007075	Immunoglobulin M	A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally was called a macroglobulin.	Gamma Globulin, 19S,IgM,IgM Antibody,IgM1,IgM2,19S Gamma Globulin,Antibody, IgM
D007128	Immunoglobulin Fragments	Partial immunoglobulin molecules resulting from selective cleavage by proteolytic enzymes or generated through PROTEIN ENGINEERING techniques.	Antibody Fragment,Antibody Fragments,Ig Fragment,Ig Fragments,Immunoglobulin Fragment,Fragment, Antibody,Fragment, Ig,Fragment, Immunoglobulin,Fragments, Antibody,Fragments, Ig,Fragments, Immunoglobulin
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000939	Epitopes	Sites on an antigen that interact with specific antibodies.	Antigenic Determinant,Antigenic Determinants,Antigenic Specificity,Epitope,Determinant, Antigenic,Determinants, Antigenic,Specificity, Antigenic
D012635	Secretory Component	The extracellular moiety of the POLYMERIC IMMUNOGLOBULIN RECEPTOR found alone or complexed with IGA or IGM, in a variety of external secretions (tears, bile, colostrum.) Secretory component is derived by proteolytic cleavage of the receptor during transcytosis. When immunoglobulins IgA and IgM are bound to the receptor, during their transcytosis secretory component becomes covalently attached to them generating SECRETORY IMMUNOGLOBULIN A or secretory IMMUNOGLOBULIN M.	Secretory Piece