Genetic linkage between serum levels of the third component of complement and the H-2 complex

A new cytotoxic lymphocyte-defined antigen coded by a gene closely linked to the H-3 locus

F1 complementation results indicate that a new gene, putatively controlling a minor histocompatibility antigen, is closely linked to the minor histocompatibility gene, H-3, in the fifth linkage group of chromosome 2 of the mouse. This gene controls a product that was capable of inducing as well as acting as a target for cytotoxic lymphocytes (CTL). The lytic activity of CTL developed in B10.LP-H-3D mice specific for the product of the new gene of B10 was restricted to target cells possessing H-2Db antigens. This contrasts to the H-2Kb-restricted activity of H-3.1 specific CTL.

Role of the fourth complement component (C4) in the regulation of contact sensitivity. II. Qualitative differences between C4 molecules from high- and low-C4 mouse strains

Lymph node cells collected from CBA/J mice 4 days after painting with picryl chloride induce contact sensitivity in naive recipient mice by virtue of hapten IgM immuno complexes. The immunizing capacity of these cells ("4-day" cells) is abolished after incubation of the cells with a C4-deficient guinea pig serum reconstituted with plasma or purified C4 from mice with high C4 levels (C4h), but not with plasma or purified C4 from mice with low C4 levels (C41). The inhibition of the immunizing capacity of 4-day cells is due to the activation of the early components of the classical complement pathway which is likely to result in the solubilization of membrane-bound immunocomplexes. However, the same amounts of CBA/J and BALB/c C4 have a different effect in inhibiting the induction of contact sensitivity by 4-day cells. In fact, by dose-response experiments, we have found that the amount of C41 able to inhibit the induction of contact sensitivity is about threefold higher than that of C4h. Analysis of the covalent binding ability of C4h and C41 reveals that C4h is able to bind to the surface of 4-day cells more efficiently than C41 and this probably accounts for the difference of the two C4 molecules in inhibiting the immunizing capacity of 4-day cells. Results are discussed in terms of different reactivities of C4h and C41 with the surface of 4-day cells.

Conservation of structural and functional domains in complement component C3 of Xenopus and mammals

The cDNA sequence and the deduced amino acid sequence of the Mr 34,000 C-terminal fragment of Xenopus laevis complement component C3 are presented. The sequence of Xenopus C3 has 57% nucleotide identity to the corresponding sequence of human C3 and approximately 49% amino acid identity to C3 from human, mouse, and rabbit. The Xenopus C3 sequence shows clusters of high and of low similarity to the mammalian C3 sequences. One of these regions of high similarity represents the domain of mammalian C3b involved in the binding of properdin, a regulator of the alternative pathway of complement activation. It is not clear whether the other highly conserved regions are involved in binding to other C3 ligands. The Xenopus C3 sequence completely lacks the Arg-Gly-Asp sequence, which has been suggested to be the recognition site of the human complement receptor type 3 on the iC3b fragment of human C3. The Xenopus C3 gene is shown not to be linked to the Xenopus major histocompatibility complex, as is also the case in mammals. Since the gene of the related molecule C4 is MHC-linked in both mammals and Xenopus, the C3 and C4 genes may have separated before Xenopus and mammals speciated.

Tumor necrosis factor/cachectin. Induction of hemorrhagic necrosis in normal tissue requires the fifth component of complement (C5)

TNF induces hemorrhagic necrosis (HN) when injected into skin exposed to bacterial agents but not when injected into normal skin. In this paper, we present several lines of evidence suggesting that TNF requires the fifth component of complement (C5) to induce HN in skin exposed to bacteria. First, mouse strains that do not have C5 did not develop HN after injection of TNF and bacteria into skin. Second, plasma from C5-sufficient mice could correct the defect in these C5-deficient mice. Third, heating at 56 degrees C for 30 min inactivated the capacity of plasma to reconstitute C5-deficient mice. Fourth, CVF, which is known to inactivate complement, abrogated the capability of C5-sufficient mice to respond. Fifth, depleting plasma of hemolytic activity while generating C5a did not affect the capacity of the activated plasma to reconstitute C5-deficient mice. Finally, only the plasma fraction containing molecules of the size range of C5a reconstituted C5-deficient mice. These findings indicate that C5a and not the membrane attack complex is required for HN. Although we do not know through which mechanism C5a participates in the development of HN, we propose that the described HN response is related to a local defense mechanism in which TNF and C5a lead to the disruption of capillaries in the direct vicinity of bacteria. By this mechanism the rapid spread of bacteria or their products into the circulation is prevented. Such a tissue response is consistent with the known higher susceptibility of C5-deficient mice to bacterial infections and provides a model with which to search for the multiple steps involved in this important local defense mechanism.

Genetic control of C3 production by the S region of the mouse MHC

The present paper reports evidence indicating that the level of the third complement component (C3) is regulated by the S region of the murine H-2 complex. In fact, using congenic strains of mice we demonstrate that mice with the k haplotype at the S region show high C3 levels, whereas mice with the d haplotype at the S region show low C3 levels.

Influence of mouse genotype on passive systemic anaphylaxis by immune complexes

The influence of mouse genotype on passive systemic anaphylaxis (PSA) by immune complexes was studied. PSA was induced by using Brucella abortus endotoxin as the antigen and rabbit anti-Brucella endotoxin antisera. Experiments using syngeneic mice as well as mice congenic for H-2 showed that the H-2 haplotype influenced the sensitivity of mice to PSA. Among the H-2 haplotypes studied, H-2b was the most sensitive, followed by H-2k and H-2d. Experiments using passive transfer of serum as well as the complement inhibitors suramin and flufenamic acid indicated that variations in complement levels under control of H-2 may be responsible for the effects described. Cyproheptadine, a blocker of serotonin and histamine receptors, and imidazol-alpha-ketoglutarate, an inhibitor of thromboxane synthesis, inhibited PSA, indicating that platelet aggregation, possibly mediated by activated components of the complement cascade, is an important feature in the development of PSA reactions in this system. Differences between strains for protection by cyproheptadine and for the effect of complement inhibitors indicated a role of early components of the classical pathway in this model.

Induction of the acute-phase protein serum amyloid P in experimental Chagas' disease

Serum amyloid P protein (SAP), which shares several structural properties with C-reactive protein, has been recently identified as an acute-phase reactant in mice. In this study, the systemic inflammatory response of mice to infection with Trypanosoma cruzi was characterized with respect to induction of SAP as well as to stage-specific alterations on complement C3 and C4 levels. The SAP response depended on the dose and infectivity of the parasites. Kinetic data indicated a close temporal relationship between the onset of parasitemia and induction of SAP. The levels of SAP were maximally enhanced (1,050%) by the time parasitemia started to regress, and the response remained elevated as the infection entered the latency phase. The decline in parasitemia was paralleled by a significant reduction in C3 levels. A reciprocal relationship between the extent of parasitemia and SAP/C3 levels became apparent when these parameters were compared in individual inbred mice during the time of decreasing parasitemia.

Studies on murine Ss protein: demonstration that S region encodes structural gene for fourth component of complement

Although genes controlling the expression of certain complement components have been shown to be linked to the major histocompatibility complex of several species, the structural genes that encode these molecules have been more difficult to map. In this study, the three constitutive polypeptide chains of the fourth component of murine complement (C4) (alpha, beta, and gamma) were isolated from 14 different inbred strains and compared by peptide mapping on analytical sodium dodecyl sulfate gels. The peptide patterns of the alpha and gamma subunits appeared to be nearly identical, but two distinctly different patterns were observed for the C4 beta chain. This structural variant was mapped to the S or G region and, as such, provides direct evidence that a structural gene for a complement component is encoded within a major histocompatibility complex.

Murine natural anti-tumor antibodies. I. Rapid in vivo binding of natural antibody by tumor cells in syngeneic mice

A competitive radioimmunoassay (RIA) for the detection of cell-bound antibody was used to study the in vivo acquisition of immunoglobulin (Ig) by tumor cells. Several tumor lines acquired Ig rapidly between 3 and 18 h after intraperitoneal implantation into normal syngeneic mice and this Ig was recovered by elution with basic or acid buffers. The Ig eluted from the L5178Y lymphoma showed higher binding to the L5178Y than to thymocytes, bone-marrow cells, 1509a sarcoma and P-815-X2 mastocytoma. In addition, binding of the eluates to the L5178Y was specifically inhibited by L5178Y cells or by solubilized membrane antigens of the L5178Y. The in vivo acquisition of Ig by the L5178Y could also be blocked by the IV and IP injections of tumor antigen although both L5178Y and 1509a solubilized membrane antigens were effective. Some of the Ig acquired by the tumor cells was found to be complement-fixing antibody since normal rabbit complement lysed 80% of L5178Y cells obtained from the peritoneal cavity of syngeneic mice 18 h after implantation, but did not lyse in vitro L5178Y cells. The in vivo binding of the complement-fixing antibodies was also inhibited by tumor antigens in the same way as the acquisition of Ig detected by RIA. It was shown that the acquisition of Ig during the first 18h of IP growth was a T-independent phenomenon because tumor cells acquire as much Ig in AT X BM mice as in sham-thymectomized controls. In a study with 11 different clones derived from the L5178Y lymphoma, a high correlation (r = 0.75, p less than 0.005) was found between the amount of Ig acquired after in vivo implantation and the amount of Ig bound to the cells after in vitro incubation with normal syngeneic serum. It is suggested that the rapid in vivo acquisition of Ig was due to the in vivo binding of natural antibodies to tumor cells.

A sensitive hemolytic assay for mouse C3

We have developed a sensitive hemolytic assay for mouse C3, utilizing readily available guinea pig complement components and standard techniques, which allows C3 to be detected in mouse serum diluted many thousand-fold. Mouse serum also contains a potent, relatively heat-stable C3-inactivator system, which is largely blocked by Suramin.

A microassay for the determination of hemolytic complement activity in mouse serum

A 51Cr release microhemolytic complement assay is described to detect hemolytic complement activity in mouse serum, 51Cr-labeled sheep erythrocytes (SRBC) which have been sensitized with a subagglutinating amount of the 7S IgG fraction of rabbit anti-SRBC serum are placed in microtiter plates and further antibody added to each well prior to the addition of the complement (C) source. The IgG antibody was found to be more efficient in the lytic assay than the 19S IgM antibody. The assay is simple to perform, reproducible, and requires small volumes of mouse serum. Comparative hemolytic values were established for serum from a variety of murine strains using pooled BALB/c serum as the C reference. No apparent relationship was noted between the H-2 type of inbred mouse strains and the presence or absence of hemolytic complement.

Absence of the eighth component of complement in association with systemic lupus erythematosus-like disease

A 56-yr-old black woman with absence of the eighth component of complement and a disease compatible with systemic lupus erythematosus is described. Her disease is characterized by the presence of photosensitive "malar" rash, alopecia, polyarthritis, and nephrotic syndrome. Hemolytic and immunochemical assays of the serum complement components were normal, except for C8 which was undetectable. Hemolytic activity could be restored to normal by the addition of functionally pure C8. In vitro tests to investigate the functional integrity of the classical and alternative pathways indicated that the functions mediated by activation of C3 and C5 were intact whereas heatlabile bactericidal activity was totally absent. Addition of C8 restored this function to normal levels. One of two brothers of the proband was shown to have serum C8 levels approaching 50% of normal indicating the hereditary nature of the defect. HLA typing studies showed that the normal brother had identical haplotypes to the proband while the proposed heterozygous brother only shared one haplotype with the patient, suggesting that the gene controlling the C8 defect was not closely linked to the major histocompatibility complex. If the association of a connective tissue disease and absence of a terminal component of complement is not coincidental, these results suggest that C8 deficiency may be associated with a subtle defect in the defense mechanisms to viral infection leading to viral persistance and perhaps to diseases such as systemic lupus erythematosus where chronic viral infections have been implicated.

Genetic loci of components of the classical and alternate pathway of complement activation: a new dimension of the immunogenetic linkage group (HLA) on chromosome 6 in man

In this review, a working hypothesis is put forward that functional cooperation of various types of cells and proteins in immune recognition, mediation and response is maintained by a common chromosomal region which evolved over millions of years from a common ancestor by gene duplication. In brief, the known functions of the H-2 complex are discussed (susceptibility and resistance to viral infection, immune response genes, T-B cell interaction as non-self recognition and response). The addition of loci of the classical and alternate pathway of complement activation to the HLA region (i.e., C2, C4 and the Bf system) is reviewed with respect to functional relationship to immune recognition and mediation mechanisms. As expected according to this hypothesis, genes for late-acting components (C3, C5, C7 and C8 in man, C5 in mice) have so far not proved to be linked to HLA.

HLA antigen studies in a family with C2 deficiency

Two children in a family were found to be homozygous for C2 deficiency; both parents and a third child were heterozygous. C2 deficiency was associated with the HLA haplotypes carrying the antigens B18 and DW2. Antigen A10 was absent in this family. Mixed lymphocyte culture studies among the family members confirmed the association of C2 deficiency with the HLA-D locus.

The complement system in tumor immunity: significance of elevated levels of complement in tumor bearing hosts

The elevation of complement level in the sera and depressed state of tuberculin reaction were observed in lung cancer patients. A clinical follow-up study demonstrated negative conversion of tuberculin reaction while keeping the complement at an elevated level during the observation period. This phenomenon can be explained; the complement system is elevated to compensate the depressed cell-mediated system to prevent the immunological surveillance system from invading agents in tumor bearing hosts. The immunological states of the patients with various diseases are classified into six stages according to the tuberculin reactivity, positive or negative, and complement level: elevated, normal, or depressed. A healthy control group is composed of the group of complement normal and tuberculin positive (Stage I). Most of acute inflammation falls into the elevated level of both complement and positive tuberculin reaction (Stage II). Sarcoidosis, leprosy, and Wegener's granulomatosis are divided into the elevated level of complement and depressed tuberculin reaction (Stage III). Systemic lupus erythematosus is in Stage V with the depressed state of both tuberculin reaction and complement level. A follow-up study of lung cancer patients showed a possible chronological sequence starting from Stage I through III, and finally to V, similar to the progression-of-disease process. The biological and medical significance related to the phenomenon is discussed, standing upon immunochemical, phylogenical, and immunogenetical standpoints of complement research.

Association of serum hemolytic complement levels with the major histocompatibility complex in chickens

The total hemolytic complement (C) levels in inbred line 7 chicks and adults were lower than C levels in inbred lines 2 and 3 and in outbred chickens of the same age. In all birds, adult levels of C were obtained in 5- to 6-wk-old chickens. Analysis of F1 and F3 generations clearly showed that the C level in chickens was determined by a dominant gene(s) associated with the major histocompatibility complex. Finding this association in a nonmammal strengthens the importance of the relationship between closely linked genes controlling histocompatibility, immune responsiveness, mixed leukocyte reaction, and C activity.

Expression of C4 on human lymphoid cells and possible involvement in immune recognition phenomena

Immunochemical studies revealed the presence of the fourth component of complement (C4) on surfaces of human lymphoid cells. Antiserums to C4 inhibited the mixed lymphocyte reaction and the mitogenic response to phytohemagglutinin, suggesting a role for membrane-associated C4 in the afferent phase of immune recognition phenomena.

B-cell antibodies, Ia-like determinants, and their relation to MLC determinants in man

The HLA supergene is located in the 6th chromosome. Its position to the centromere and the position of a number of polymorphic isoenzymes has been elucidated. The HLA supergene codes not only for determinants present on all nucleated cells, but also for determinants present on B cells and absent from T cells and platelets. These determinants can be recognized by serology, and evidence is presented that some of them are coded for by a hither to unrecognized locus Ag, which is very closely linked to the MLC determinants of the D locus can be recognized with the help of the MLC test using unprimed cells, homozygous for the MLC determinants, so-called typing cells primed against one MLC determinant in the PLT test. So far, 8 MLC determinants have been recognized. Significant disease-association studies in different racial groups appear to be especially informative. They already indicate that the association found so far must rest on different mechanisms. Whether some of them could be caused by partial deficiency for one or more of the complement factors remains to be proven.

Genetic independence between the HL--A system and deficits in the first and sixth components of complement

From two families, one with Clr deficiency and the other with C6 deficiency, evidence was obtained suggesting genetic independence between the transmission of a 50% deficit in the functional activity of these two complement components and the inheritance of the HL--A system, the ABO system, and the sex of individuals.

The Bf locus in the HLA region of chromosome 6: linkage and association studies

Bf allele frequencies in a material of 172 unrelated Norwegians are given. Bf/HLA linkage relations in 49 informative matings with 178 children, and Bf/HLA association data of a material of 212 Bf-HLA haplotypes are presented. Of 171 informative meioses, there were no Bf-HLA-B recombinations, while 3 out of 158 Bf-HLA-A informative meioses showed recombination. There is significant association between the BfF and the HLA-BW35 allele. It is concluded that the Bf locus is situated on the HLA-B side of HLA-A within the HLA region, in very close proximity to HLA-B.

Genetics of the complement system

The complement system, unlike the coagulation system, was largely characterized by in-vitro techniques which did not make use of genetically deficient plasmas. The existence of the genetically deficient plasmas. The existence of the genetically deficient subjects therefore has served largely to increase our knowledge of the in-vivo role of complement. At the present time its clearest role is in the resistance to infection; obviously in the case of C3 deficiency and bacterial infection and possibly more subtly in the case of deficiency of the early active complement components and low virulence organisms. There is so far no evidence that genetic complement deficiency interferes with antibody formation or with the generation of tolerance as has been suggested in the pas (Azar et al, 1968; Dukor and Hartmann, 1973).

Studies on the murine Ss protein. I. Purification, molecular weight, and subunit structure

The murine Ss protein has been isolated and purified. Using specific antisera, the radiolabeled protein has a mol wt of 120,000 in sodium dodecyl sulfate polyacrylamide gels. It is composed of two basic subunits of 23,000 and 14,000 daltons. The smaller molecular weight subunit contains a single disulfide bridge, is devoid of carbohydrate, and may represent the murine equivalent of beta2-microglobulin.

Mixed lymphocyte culture determinants and C2 deficiency: LD-7a associated with C2 deficiency in four families

Four families with C2 deficiency were studied. Among eight HL-A haplotypes involved with C2 deficiency, five were HL-A 10,W18. Three homozygotes for C2 deficiency from different families were mutually nonreactive in mixed lymphocyte cultures (MLC) and the heterozygotes from the fourth family failed to react to the homozygous cells. It appeared that identical MLC determinants were associated with all the genes from the different families that related to C2 deficiency. Further experiments identified the MLC determinant, LD-7a, as being involved. These results suggest marked linkage disequilibrium between the genes for C2 deficiency and the major histocompatibility complex (MHC). Studies of possible recombinants have offered tentative evidence for the positioning of the locus for C2 deficiency with respect to other segments of the MHC.

Hereditary C2 deficiency: Genetic studies and association with the HL-A system

Herediatary C2-deficiency has been shown to be transmitted asn an autosomal recessive characteristic. Recent evidence indicates that some genetic factors involved in the control of the complement (C) system in both man and mice are governed by genes localized within the major histocompatibility regionmthis study describes a large pedigree of the paternal family of a C2-deficient patient with systemic lupus erythematosusl It is shown that this condition is transmitted as an autosomal recessive trait, the heterozygous carriers having approximately half normal levels of C2. Furthermore, this trait was shown to be inherited in close linkage with an infrequent HL-A typw, 2,4A2. The maternal, C2-defective chromosome was shown to be transmitted by HL-AW10, W18 haplotypemthis same haplotype was described in a similar study by Fu et al. (6) to be associated with C2 deficiencymfinally, a third haplotype HL-A2,W18 carrying a defective C2 gene was demonstrated in a part of this pedigree.

Linkage group HL-A-MLC-BF (properdin factor B). The site of the Bf locus at the immunogenetic linkage group on chromosome 6

Genetic linkage between the HL-A and Bf loci could be confirmed in 43 families with 168 offspring. In 4 families, 5 recombinants out of 82 informative meiotic divisions were observed (r = 6.1%). The localisation of the Bf marker system was studied in 3 families with crossovers between HL-A and MLC. From these data the following map order of human chromosome 6 can be proposed: HL-A (1st locus) -- HL-A (2nd locus)--MLC-Bf---PGM(3). The fact that important components of the classical and alternate pathway of complement activation are governed by genes closely linked with HL-A and MLC loci leads to the proposition to include the Bf system into the Major Histocompatibility Complex in man.