Immunology Today February1982
C-reactive protein and the acute phase response from M. B. Pepys
L Electron micrographs of negatively stained preparations of human C-reactlve protein (A) and h u m a n serum amyloid P c o m p o n e n t (B). Most molecules are seen face-on but arrows in (B) and insets in (B) (at higher magnification) show views of the disc-llke molecules slde-on. Magnification x 320,000. Courtesy of Dr E. A. Munn, ARC Institute of Animal Physiology, Babraham, Cambridge.
Following most forms of tissue injury, inflammation, infection or malignant neoplasia in homoiothermic animals the circulating concentration of many plasma proteins increases significantly. This increase, known as the acute phase response, was first described for C-reactive protein (CRP), so-called because its discovery stemA conference 'C-reactive protein and the plasma protein response to tissue injury' was held at the Barbizon-Plaza Hotel, New York, 21-23 September 1981. The proceedings wilI be published in Anrzah qf g/w ,%'w Ybrk Acade, O' qf Niencey, 1982.
reed from its ability to precipitate the somatic C polysaccharide of pneumococci. Among the other acute phase proteins are a number of proteinase inhibitors, coagulation, complement and transport proteins and some proteins, like CRP, whose normal functions are unknown. One of these, serum arnyloid A protein (SAA), is of particular interest because it seems to be the precursor of amyloid A (AA) protein. Amyloidosis is a rare but serious complication of those chronic inflammatory diseases characterized by a sustained acute phase response and high SAA levels. Amyloid fibrils tbrmed of AA are C~mld.onp. 28
Cornplement research
Judging the state of the art from Peter Lachmann
Complement workshops are rather special meetings. Even among immunologists complement is regarded as a somewhat esoteric topic and it is only at these workshops that the sub]ect can be discussed at a fully technical level with confidence that the audience is well acquainted with the background. They are therefore important meetings for complement workers and are used to give a periodic picture ot the state of the art. The directions in which complement research is going and the extent to which past problems and disputes have been resolved can be judged by comparing the proceedings of one workshop with the next. The ninth international complemcnl workshop was held in bright sunshine at Key giscayne, Florida, from 22 25 November. Over 300 workers took part in a tightly-packed program and what follows can give only a subicetire view of some of the highlights. One topic new to this workshop ~as the introduction of recombinant I-)NA genetics to complement. A cl)NA probe for mouse C3 has been made and the majority of the genomic DNA coding for C3 has now been identified and some sequencing begun. With the help of these clones (and by otheT means) it has been possible to shov, that the C3 gene in man is found on the 19thchromosome a rather small and unobtrusive chromosome not known to code for any other p,'oteins of immunological interest. DNA clones coding for Factor B were also reported which will allo,* the analysis of the complement region of the MHC. 'Fhere were also some new tindings ( , m i d . ,m I, 2, ~ L l ~ e , i ~ , Bi,,,,,~di, at I',, , , i,~s
I)I07-1UIg/S2/{){)(~{)I){)qa()/S2
28 Continuing v i g o u r - ¢ontd on 'protein' genetics of complement. C8. it would now appear, is not a single protein at all but a complex that can be tbrmed in plasma fi'om two sub-cnmponents (the beta and the alpha-gamma chains) and these two sub-components have been shown to be coded in unlinked parts of the genome, taking advantage of the fact that deficiencies of both occur and can be used as reagents fi)r studying the polymorphism of the other subcomponent. It was fortunately not proposed that the nomenclature for C8 should be changed. A surprise came from the description of the first family with properdin deficiency. This component - alone so far of complement components appears to be coded on the X chromosome since the deficiency shows sex-linked recessive inheritance. A further' surprise was the apparently extraordinarily high incidence of C9 deficiency that has been reported in .Japan. The cstimate was put forward that there may be as many as 50,000 C9-deficient Japanese (although this was a projection from a much smaller ascertained figure). Nevertheless, if such estimates are anything like accurate it would probably be necessary to assume that there is som/e selective advantage in Japan for at any rate the heterozygous state of C9 deficiency. There was a customary vigorous session devoted tn the mechanisms of complement-induced membrane damage. The controversies between 'leaky patch' and 'trans-membrane channel' appear to have been at least in part resolved since all groups now seem to agree that a transmembrane channel is formed and furthermore that it is lined by polymers of C9. There remains some dift?rence of opinion about the size of the polymers, estimates going as high as dodecamers. That a qeaky patch' may occur as well is not excluded and the mechanism by which complement lysis occurs, albeit slowly, in the total absence of C9 slill requires adequate explanation. Another striking innovalion at this workshop was the exlensive adoption in complement work of the monoclonal antibody technique. Monoclonal antibodies to C3 were first described at the previous workshop but now monoclonal antibodies to complement components and receptors have become commonplace. Anti-
Immunub:gy "l-c~dcO,,z,d. 3, .VT~.2, t982 (J-Reactlve
bodies to C3 secm to exist in their scores and havc been used with some success to map functional sites on this highly polyfi_mctional molecule and to define yet another C3 fragment. Monoclonal antibodies to complement receptors have yet to clarify exactly how many distinct complement receptors there are how they are distributed and w~at functions are subscrved by ligands binding to them. Protein sequencing of complement proteins progresses apace. It has become clear from sequencing studies that both Factor I) and Factor l carry the sequences characteristic of serine esterases and it was further suggested, albeit not on sequence data, that C6, not previously believed to be an enzyme at all, is also a serine esterase in that it can be inhibited by DFP. Studies of biosynthesis also continue to contribute new data. It seems that, in laboratory animals at least, not all deficiencies are due to a failure to make messenger RNA. A large molecular weight precursor of Factor B has been detected and the existence of a separate and slightly larger 'membrane Factor B' was also reported from studies of biosynthesis by macrophages. Certain problems that greatly exercised the last workshop seem to have been substantially resolved. There seems at last to be general agreement on the organization and initiation of the alternative complement pathway and on the molecular mechanisms underlying the covalent bond formation between C3 and (]4 on the one hand and their acceptor molecules on the other. It is always tempting t 9 think that a field as circumscribed as complement must be reaching its end and at every workshop there are those who wonder if there will be enough material to fill another. Those who harboured these doubts 2 years ago have becn proved emphatically wrong, the present workshop showing much vigour and no sign of any loss of interest in the structure, organization or functions of the complement system. The nex]t workshop is to be held in Mainz in the Spring of 1983 and is awaited with pleasure.
P. J. 1,ac/~ma,rt A Director q~ the AIRC Me e~ Reader ir~ lmmunologual Medlczlle at the Department qf Medu'ine, Royal Portgraduate Me&cal ,S}hoo/, Lonrbm WI2 Oil& I/.K.
RAJGOPAI. RAGllUPATtlY Department qf Iramunolog~, Univerrity qf Alberta, l:'dmonlort, Alberta, (,Tmada, /gig 2t17
Reference 1 Ra.jgopal, R. and Rao, 8. S. (1979) IndiarLT. Med. Re~. 70, 439
C-reactive protein and the acute phase response from M. B. Pepys
L Electron micrographs of negatively stained preparations of human C-reactlve protein (A) and h u m a n serum amyloid P c o m p o n e n t (B). Most molecules are seen face-on but arrows in (B) and insets in (B) (at higher magnification) show views of the disc-llke molecules slde-on. Magnification x 320,000. Courtesy of Dr E. A. Munn, ARC Institute of Animal Physiology, Babraham, Cambridge.
Following most forms of tissue injury, inflammation, infection or malignant neoplasia in homoiothermic animals the circulating concentration of many plasma proteins increases significantly. This increase, known as the acute phase response, was first described for C-reactive protein (CRP), so-called because its discovery stemA conference 'C-reactive protein and the plasma protein response to tissue injury' was held at the Barbizon-Plaza Hotel, New York, 21-23 September 1981. The proceedings wilI be published in Anrzah qf g/w ,%'w Ybrk Acade, O' qf Niencey, 1982.
reed from its ability to precipitate the somatic C polysaccharide of pneumococci. Among the other acute phase proteins are a number of proteinase inhibitors, coagulation, complement and transport proteins and some proteins, like CRP, whose normal functions are unknown. One of these, serum arnyloid A protein (SAA), is of particular interest because it seems to be the precursor of amyloid A (AA) protein. Amyloidosis is a rare but serious complication of those chronic inflammatory diseases characterized by a sustained acute phase response and high SAA levels. Amyloid fibrils tbrmed of AA are C~mld.onp. 28
Cornplement research
Judging the state of the art from Peter Lachmann
Complement workshops are rather special meetings. Even among immunologists complement is regarded as a somewhat esoteric topic and it is only at these workshops that the sub]ect can be discussed at a fully technical level with confidence that the audience is well acquainted with the background. They are therefore important meetings for complement workers and are used to give a periodic picture ot the state of the art. The directions in which complement research is going and the extent to which past problems and disputes have been resolved can be judged by comparing the proceedings of one workshop with the next. The ninth international complemcnl workshop was held in bright sunshine at Key giscayne, Florida, from 22 25 November. Over 300 workers took part in a tightly-packed program and what follows can give only a subicetire view of some of the highlights. One topic new to this workshop ~as the introduction of recombinant I-)NA genetics to complement. A cl)NA probe for mouse C3 has been made and the majority of the genomic DNA coding for C3 has now been identified and some sequencing begun. With the help of these clones (and by otheT means) it has been possible to shov, that the C3 gene in man is found on the 19thchromosome a rather small and unobtrusive chromosome not known to code for any other p,'oteins of immunological interest. DNA clones coding for Factor B were also reported which will allo,* the analysis of the complement region of the MHC. 'Fhere were also some new tindings ( , m i d . ,m I, 2, ~ L l ~ e , i ~ , Bi,,,,,~di, at I',, , , i,~s
I)I07-1UIg/S2/{){)(~{)I){)qa()/S2
28 Continuing v i g o u r - ¢ontd on 'protein' genetics of complement. C8. it would now appear, is not a single protein at all but a complex that can be tbrmed in plasma fi'om two sub-cnmponents (the beta and the alpha-gamma chains) and these two sub-components have been shown to be coded in unlinked parts of the genome, taking advantage of the fact that deficiencies of both occur and can be used as reagents fi)r studying the polymorphism of the other subcomponent. It was fortunately not proposed that the nomenclature for C8 should be changed. A surprise came from the description of the first family with properdin deficiency. This component - alone so far of complement components appears to be coded on the X chromosome since the deficiency shows sex-linked recessive inheritance. A further' surprise was the apparently extraordinarily high incidence of C9 deficiency that has been reported in .Japan. The cstimate was put forward that there may be as many as 50,000 C9-deficient Japanese (although this was a projection from a much smaller ascertained figure). Nevertheless, if such estimates are anything like accurate it would probably be necessary to assume that there is som/e selective advantage in Japan for at any rate the heterozygous state of C9 deficiency. There was a customary vigorous session devoted tn the mechanisms of complement-induced membrane damage. The controversies between 'leaky patch' and 'trans-membrane channel' appear to have been at least in part resolved since all groups now seem to agree that a transmembrane channel is formed and furthermore that it is lined by polymers of C9. There remains some dift?rence of opinion about the size of the polymers, estimates going as high as dodecamers. That a qeaky patch' may occur as well is not excluded and the mechanism by which complement lysis occurs, albeit slowly, in the total absence of C9 slill requires adequate explanation. Another striking innovalion at this workshop was the exlensive adoption in complement work of the monoclonal antibody technique. Monoclonal antibodies to C3 were first described at the previous workshop but now monoclonal antibodies to complement components and receptors have become commonplace. Anti-
Immunub:gy "l-c~dcO,,z,d. 3, .VT~.2, t982 (J-Reactlve
bodies to C3 secm to exist in their scores and havc been used with some success to map functional sites on this highly polyfi_mctional molecule and to define yet another C3 fragment. Monoclonal antibodies to complement receptors have yet to clarify exactly how many distinct complement receptors there are how they are distributed and w~at functions are subscrved by ligands binding to them. Protein sequencing of complement proteins progresses apace. It has become clear from sequencing studies that both Factor I) and Factor l carry the sequences characteristic of serine esterases and it was further suggested, albeit not on sequence data, that C6, not previously believed to be an enzyme at all, is also a serine esterase in that it can be inhibited by DFP. Studies of biosynthesis also continue to contribute new data. It seems that, in laboratory animals at least, not all deficiencies are due to a failure to make messenger RNA. A large molecular weight precursor of Factor B has been detected and the existence of a separate and slightly larger 'membrane Factor B' was also reported from studies of biosynthesis by macrophages. Certain problems that greatly exercised the last workshop seem to have been substantially resolved. There seems at last to be general agreement on the organization and initiation of the alternative complement pathway and on the molecular mechanisms underlying the covalent bond formation between C3 and (]4 on the one hand and their acceptor molecules on the other. It is always tempting t 9 think that a field as circumscribed as complement must be reaching its end and at every workshop there are those who wonder if there will be enough material to fill another. Those who harboured these doubts 2 years ago have becn proved emphatically wrong, the present workshop showing much vigour and no sign of any loss of interest in the structure, organization or functions of the complement system. The nex]t workshop is to be held in Mainz in the Spring of 1983 and is awaited with pleasure.
P. J. 1,ac/~ma,rt A Director q~ the AIRC Me e~ Reader ir~ lmmunologual Medlczlle at the Department qf Medu'ine, Royal Portgraduate Me&cal ,S}hoo/, Lonrbm WI2 Oil& I/.K.
RAJGOPAI. RAGllUPATtlY Department qf Iramunolog~, Univerrity qf Alberta, l:'dmonlort, Alberta, (,Tmada, /gig 2t17
Reference 1 Ra.jgopal, R. and Rao, 8. S. (1979) IndiarLT. Med. Re~. 70, 439
