The chemical aspects of immunity / [Harry Gideon Wells].

  • Wells, H. Gideon (Harry Gideon), 1875-1943.
Date:
1929
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Licence: In copyright

Credit: The chemical aspects of immunity / [Harry Gideon Wells]. Source: Wellcome Collection.

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    down into smaller fragments it loses its antigenic properties pari passu. Zinsser 13 suggests that antigens must he noil-diffusible colloids, which therefore cannot enter the cells to he destroyed therein, so that it be- comes necessary for soluble, extracellular antibodies to be formed which may react with the foreign protein as a step in its destruction. When the foreign molecule is small enough to be taken into the cells by diffusion, antibody formation becomes unnecessary for its destruction, and consequently we have no antigens that are not colloidal. In support of this is the fact that the cleavage products of a protein, even when injected all together, have no antigenic capacity, although when in their original combined colloidal form they are antigenic, and when artificially reunited into colloidal molecules (called plasteins) the antigenic capacity of these cleavage products may be restored. Also, ultrafiltrates of bac- terial suspensions, being devoid of colloids, are not antigenic.14 The antigenic activity, as measured by the auiount or rapidity of antibody production, varies much with different proteins. Sometimes this seems to depend on the solubility of the antigen in the tissue fluids, as in the case of the vegetable proteins;15 but, in other cases, no such explanation can be found. For example, serum albumin seems to be much less strongly antigenic than the globulins from the same serum.16 Relative antigenic activity cannot be correlated with the size of the protein molecules, at least if the present assumptions as to the molecular weights of protein are correct, since egg albumin (a good antigen), and serum albumin (reputedly a poor antigen) have relatively low molecular weights,17 while high weights are assigned to euglobulin (a good antigen) and casein (a poorer antigen). With any given protein the amount of antibody formation does not vary directly with the amount of antigen injected, small doses often producing even larger amounts of antibody than larger doses.18 As a rule, the same amount of antigen in divided doses at intervals of a few days, provokes a greater antibody formation than if injected at one time, but this is not always true. There is a great individual variation in the antibody production by different animals, even of the same species, in response to the same amount of antigen. Part of this difference seems to depend on definite differences in the serology of the individual animals. For example, some 13 “Infection and Resistance,” p. 110. 1923. 14 Fernbach and Hepner, Ccntr. Bakt., 1 Abt., 100:358 (1926). ns Wells and Osborne, J. Infect. Vis., 14:377 (1914). 10 Dale and Hartley, Biochcm. Jour.. 10:408 (1916); Doerr and Merger, Z. Hyg., 96:191 (1922); Ruppel, Dent. med. IVocli., 49:40 (1923). 17 See Cohn, Physiol. Reviews, 5:349 (1925). 18 Tsen, J. Med. Research, 37:381 (1918).