Kyongsu Hong

Endolymphatic Hydrops and III Type Allergic Reaction

IgG antibody and complement are both present in endolymphatic fluid, and it is possible that immune complex may form in endolymphatic fluid. However, there are still obscure points as to whether endolymphatic hydrops is due to immune complex, but it is quite possible that it is only one causative factor in endolymphatic hydrops.

Rapid and simple measurement of human C5a-des-Arg level in plasma or serum using monoclonal antibodies

A new sandwich immunoassay method for measuring human C5a-des-Arg was developed using monoclonal antibody specifically reactive with C5a-des-Arg. Monoclonal antibodies were obtained from a panel of hybridomas produced by fusion of mouse myeloma cells, P3 X 63-AG8,653, with spleen cells from a CBF1(C57BL/6 X BALB/c) mouse immunized with purified C5a. The reactivities of these monoclonal antibodies against C5a, C5a-des-Arg and C5 were tested by solid-phase radioimmunoassay. One of the antibodies reacted with C5a-des-Arg, but not with C5a and C5. By use of this antibody for capturing antibody in sandwich immunoassay, a rapid and simple method was developed for measuring C5a-des-Arg without previous removal of C5. The sensitivity of this assay system was approximately 1 ng/ml for C5a-des-Arg.

Plasmodium berghei: Sporozoites are sensitive to human serum but not susceptible host serum

Human complement was activated by rodent malaria, Plasmodium berghei, sporozoites through the alternative pathway, as revealed by C3 deposition on sporozoites using the fluorescent antibody technique. Sporozoites exposed to fresh human serum decreased in infectivity to HepG2 cells, but those exposed to heated or C3-deficient human serum showed normal infectivity to HepG2 cells. In contrast, C3 deposition was not observed on the sporozoites treated with mouse or rat serum even in the presence of specific polyclonal anti-sporozoite antibody. However, following treatment with trypsin (250 micrograms/ml), 81% of salivary gland sporozoites and 49% of oocyst sporozoites became reactive with mouse serum, and reactive sporozoites deposited mouse C3 on their surface in the presence of 30 mM EGTA and 1 mM Mg2+ without antibody. Concomitantly some sporozoites lost reactivity to anti-circumsporozoite protein monoclonal antibody. These results suggest that P. berghei sporozoites possibly express surface molecules that regulate the complement activation pathway of susceptible hosts but not of nonhosts, and that the putative structures consist of protease-sensitive molecule(s) which are closely associated with the circumsporozoite protein.

Number of hits necessary for complement-mediated hemolysis

The number of hits necessary for the C8 and C9 steps of immune hemolysis was reexamined with a previously unemployed experimental design, in which various numbers of EAC1–7, excess of the supplementary component and a constant amount of the component tested were incubated in a constant volume (Inoue et al. 1976. Infect. Immun. 13: 337). Our results were consistent with previous findings; the steps of guinea pig C8 and C9, and human C8 each followed a one‐hit mechanism, while that of human C9 showed a multi‐hit response. When lysis of sensitized erythrocytes (EA) by normal human serum was analysed in a similar way, one‐hit curves were obtained. This result, taken together with the above results, suggests that immune hemolysis occurs by a single lesion including a single C8 and multiple C9 in the case of human complement and that normal human serum contains sufficient excess of C9. On the other hand, when C9‐deficient human serum was used for lysis of EA, multiple‐hit curves were obtained. The mechanism of lysis by C5b‐8 may differ from that by C5b‐9.

Interaction of the Eighth Component of Guinea Pig Complement(C8) with the Membrane-Bound C5b-7 Complex--The Binding Site of C8 to C5b-7 is Formed on Association of the α-γ Subunit with the β-Chain

The eighth component (C8) of guinea pig complement consists of three polypeptide chains, the α‐, β‐, and γ‐chains with M.W. of 60,000, 60,000, and 24,000, respectively. The α‐ and γ‐chains are bound by a disulfide bond(s) forming an α‐γ subunit, which is linked noncovalently to the β‐chain.