Relationship between Molecular Size and Intra- and Extravascular Distribution of Protein Antigens

[摘要] Plasma proteins varying in molecular weight from 50,000 to 950,000 were radiolabeled and injected into rabbits and the lymph to plasma concentration ratios (CL/CP) of the various proteins were measured 3 days following injection. The amount of protein in the extravascular fluid spaces after equilibration, as measured by the CL/CP, correlated exponentially with the effective hydrodynamic diffusion radius of the protein. An exponential relationship also was observed between CL/CP and molecular weight for globular proteins, whereas fibrinogen, which is a spindle-shaped protein, showed only a correlation with the effective hydrodynamic diffusion radius and not with the molecular weight. No correlation between the intra- and extravascular distribution and half-lives of the various homologous and heterologous proteins was observed. The immunoglobulins of similar molecular size, but different chemical structure, as human γA-monomer, human γG and rabbit γG, showed a similar lymph to plasma concentration ratio following equilibration.Following intravenous injection, a larger percentage of bovine serum albumin (BSA) complexed with Fab fragments from purified anti-BSA remained in the intravascular fluid spaces than of BSA alone after complete equilibration.Similar to the CL/CP, the calculated extravascular lymph space occupied by the various proteins correlated exponentially with the effective hydrodynamic diffusion radius of the protein.The importance of the in vivo distribution and the behavior of protein antigens in relation to immunologic phenomena is discussed. With a given blood concentration, the concentration of serum protein antigens in the extravascular fluid space varies considerably with antigens of different molecular sizes.

[学科分类] 生物科学（综合）