Antigenic determinant. See

Antigen A molecule that is capable of binding to an antibody. Antigenic Determinant See Epitope. 

When grown at 25°, mycelia, or conidia mixed with mycelia, produce di-O-rhamnosyl side-chains (see the preceding) that are the main, antigenic determinants, as shown by inhibition experiments with oligosaccharides and rabbit immune serum.131 The response of human sera to the polysaccharide, and the fact that 13C-n.m.r. spectroscopy showed that conidia of S. schenckii form a rhamnomannan similar to the yeast component and different from the di-O-rhamnosylman-nan of hyphae,132 suggest the formation of hyphae in vivo. 

Urinary casts, often excreted by patients having renal disease, possess414 antigenic determinants in common with the Tamm-Horsfall protein (see p. 414), and, indeed, this glycoprotein is the major component of the casts.414-416 However, the reason for its aggregation is as yet unknown. Other pathological states may well be found to be associated with abnormalities in the structure or metabolism, or both, of glycoproteins. 

There are five classes of immunoglobulins that can be distinguished by antigenic determinants on the heavy chains (see later), namely, IgM, IgG, IgA, IgD, and IgE. Antibody activity has been demonstrated in each of the classes. The molecular organization of immunoglobulins is based on a four-chain, unitary structure con-... 

Dideoxyhexoses. Several bacterial antigenic determinants with the general structure of 3,6-dideoxyhexoses occur in the cell wall of Pasteurella and Salmonella strains. Most of the transformations reported so far occur as cytidine nucleotides (see Table I, References 15, 16, 17, 18, 19). Here, again the first step is the transformation of the cytidine diphospho-linked glucose into its corresponding 4-keto derivative. By at least two distinct steps, requiring NADPH, reduction to several different 3,6-dideoxyhexoses have been reported. One 3,6-dideoxyhexose CDP-tyvelose (3,6-dideoxy-D-arabino hexose) is formed by a specific 2-epimer-ase from CDP-paratose (24). 

The antigenic determinants of the native lysozyme molecule appear to include most, if not all, of the surface residues, as evidenced by numerous studies (reviewed critically by Benjamin et al., 1984). This point of view contrasts with that of Atassi and Lee (1978), who claimed a limited antigenicity, based on a study of surface-simulated peptides. The sites delineated by the latter workers do not include Arg-68 (Fainanu et al., 1974), the loop region in general, or any of several other segmental regions previously demonstrated to function in this capacity, such as residues 1—20 and 123-129 (see Benjamin et al., 1984). 

This number is equal to that of the precipitation zones, provided that what one is counting is actually antigen-antibody precipitation zones and not something else (see discussion of sources of error). The number of antigens determined is a minimum number because the concentration of the antibodies against one antigen (or of an antigen) may be below the threshold detectable value and because a precipitation zone may be hidden by others, especially when they are numerous. 

Immunoglobulin G (IgG) subclasses—There are four subclasses, called IgGl, IgG2, IgG3, and IgG4, which show sequence differences in the C-domains (see Fig. 4) they also show differences in their antigenic determinants. 

The fusion of an Immortal myeloma cell and a single B lymphocyte yields a hybrid cell that can proliferate indefinitely, forming a clone called a hybridoma (see Figure 6-38). Because each Individual B lymphocyte produces antibodies specific for one antigenic determinant (epitope), a hybridoma produces only the mono-... 

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