Use of the ELISA to detect and quantify histocompatibility antigens and their subunits

A solid phase enzyme immunoassay (ELISA) has been developed for the detection and quantification of human histocompatibility antigens and their subunits. The assay involves the binding to a microELISA plate of a mouse monoclonal antibody reacting with a common antigenic determinant to all HLA (A, B, C) antigens. The standard conditions for the assay and the curves obtained for the quantification of total HLA, free beta 2m, and free heavy chain subunit (alpha) present in a biological sample are described and the sensitivity and potential uses of the method are discussed.

Genetic polymorphism of human C4-binding protein

Two different forms of human C4-bp, C4-bp A and C4-bp B, have been identified by isoelectric focusing (IEF) of neuraminidase-treated EDTA-plasma samples. Family studies demonstrate Mendelian segregation of these forms, indicating that they are under gentic control. This conclusion is supported by IEF analysis of the two variants purified by affinity chromatography. Under completely denaturing conditions, C4-bp B was found to be composed of two subunits that focused at different pH, whereas C4-bp A contains only the more basic one. These results suggest that a single autosomal locus with at least two codominant alleles coding for the subunits controls the IEF variation of C4-bp in humans. The allele designated C4BP*1 codes for a subunit that, after neuraminidase treatment, focuses at pH = 6.65. The allele C4BP*2 codes for a different subunit that focuses at pH = 6.60. The C4-bp A phenotype corresponds to the genotype C4BP*1,C4BP*1 and the phenotype C4-bp B to the genotype C4BP*1,C4BP*2. The phenotype corresponding to the C4BP*2,C4BP*2 homozygous genotype has not been encountered thus far. Initial linkage data indicate that the C4BP locus is not closely linked to either the HLA or to the C3 loci.

Genetic polymorphism of human C4-binding protein

Two different forms of human C4-bp, C4-bp A and C4-bp B, have been identified by isoelectric focusing (IEF) of neuraminidase-treated EDTA-plasma samples. Family studies demonstrate Mendelian segregation of these forms, indicating that they are under gentic control. This conclusion is supported by IEF analysis of the two variants purified by affinity chromatography. Under completely denaturing conditions, C4-bp B was found to be composed of two subunits that focused at different pH, whereas C4-bp A contains only the more basic one. These results suggest that a single autosomal locus with at least two codominant alleles coding for the subunits controls the IEF variation of C4-bp in humans. The allele designated C4BP*1 codes for a subunit that, after neuraminidase treatment, focuses at pH = 6.65. The allele C4BP*2 codes for a different subunit that focuses at pH = 6.60. The C4-bp A phenotype corresponds to the genotype C4BP*1,C4BP*1 and the phenotype C4-bp B to the genotype C4BP*1,C4BP*2. The phenotype corresponding to the C4BP*2,C4BP*2 homozygous genotype has not been encountered thus far. Initial linkage data indicate that the C4BP locus is not closely linked to either the HLA or to the C3 loci.

Murine sex-limited protein (Slp) antigenic sites in human complement component C4

Human complement component C4 is encoded by two HLA-linked loci, A and B. In the mouse, the H-2 region contains structural genes for two serum proteins that react with antibodies to human C4, but one of these proteins (Slp) has no C4 hemolytic activity. Because the product of C4-A locus in man has low hemolytic activity, a previous report suggests it may be the homologue of murine Slp. We show here that Slp antigenic determinants are found in human C4. However, they are expressed in the products of both loci A and B, that is, C4A and C4B, since both proteins were specifically immunoprecipitated by the IgG fraction of alloantisera to mouse Slp. Therefore, Slp-associated structural features are preserved in evolution, although they do not seem to be relevant to the hemolytic properties of C4.

The murine sex-limited protein (Slp): reassessment of its sex limitation

Previous studies in which an alloantiserum was used to measure Slp levels indicated that in certain inbred strains of mice (Slpa), this protein was sex-limited, that is, present only in males. We raised several monoclonal antibodies directed against different epitopes of Slp and used them to develop a sensitive two-site immunoradiometric assay. Using this assay we detected Slp in serum of all Slpa females previously thought to be phenotypically negative. The levels of Slp in these females are about 0.2 to 4% of that of the males of the same inbred strain. The molecule found in serum of females was isolated by affinity chromatography and was found to have the characteristic three-chain structure of male Slp. These findings establish that the presence of Slp in Slpa females is the rule rather than the exception. Quantitative differences similar in magnitude to those found between males and females were also detected among Slpa males; i.e., Sd males have about 100 times more Slp than Sp males. The mechanisms by which androgens determine the extensive quantitative male-female differences, and by which the S region determines large variations among Slpa males, are unknown.

The murine sex-limited protein (Slp): reassessment of its sex limitation

Previous studies in which an alloantiserum was used to measure Slp levels indicated that in certain inbred strains of mice (Slpa), this protein was sex-limited, that is, present only in males. We raised several monoclonal antibodies directed against different epitopes of Slp and used them to develop a sensitive two-site immunoradiometric assay. Using this assay we detected Slp in serum of all Slpa females previously thought to be phenotypically negative. The levels of Slp in these females are about 0.2 to 4% of that of the males of the same inbred strain. The molecule found in serum of females was isolated by affinity chromatography and was found to have the characteristic three-chain structure of male Slp. These findings establish that the presence of Slp in Slpa females is the rule rather than the exception. Quantitative differences similar in magnitude to those found between males and females were also detected among Slpa males; i.e., Sd males have about 100 times more Slp than Sp males. The mechanisms by which androgens determine the extensive quantitative male-female differences, and by which the S region determines large variations among Slpa males, are unknown.

A simplified two-dimensional electrophoretic technique

The two-dimensional electrophoretic O'Farrell technique can be simplified in terms of effort and equipment. This simplification derives mainly from the fact that the first dimension (isoelectric focusing) is run in a vertical slab gel. Since all tracks are cast in a single template, a reproducible and uniform first dimension is obtained, allowing easy and accurate comparison among tracks after standard staining and/or radioautographic procedures. After the first dimension, the focused tracks are cut and, following equilibration, simply laid on top of the second dimensional slab gel, whose spacers are 0.1 mm thicker than those used in the first separation. Thus, basically the same equipment can be used for both dimensions. This modified technique has been experimentally validated since it has allowed the detection of structural variants of two proteins related to the mouse complement system, namely, the fourth component and the sex-limited protein.

cis-Interacting genes in the S region of the murine major histocompatibility complex

Insight into the control of gene expression may be gained by analysing genetic systems marked by both regulatory and structural variants. In such systems one can determine whether a regulatory element controls structural genes on both chromosomes or only on the chromosome to which it is linked. The latter may be detected in individuals heterozygous at both the regulatory and structural loci, in which case the effect of each regulatory allele is seen to be exerted only on the cis-located structural allele. In prokaryotic organisms, the identification of cis interaction of this sort has allowed elucidation of many features of genetic regulation, first for the lac operon and subsequently for a variety of other systems. In higher organisms, however, there have been few opportunities to observe cis-interacting genes. The most thoroughly characterized mammalian system in this regard is the murine beta-glucuronidase locus described by Paigen and his colleagues, in which cis interaction has been shown to occur between two closely linked genetic elements-the beta-glucuronidase structural gene itself and an androgen-activated regulatory gene which controls the quantity of beta-glucuronidase expressed. We report here that cis-interacting genetic elements are also found in the S region of the mouse major histocompatibility complex H-2.

H-2-controlled polymorphism of the gamma chain of Slp (sex-limited protein)

A genetic polymorphism detected by the O'Farrell two-dimensional technique (isoelectric focusing and SDS-PAGE) of the murine sex-limited protein (Slp) is described and shown to map to the H-2 complex. The Slp charge variation was found to be in the gamma chains. Inbred strains carrying the H-2w7 and H-2wr7 haplotypes, which are derived from a wild mouse, had Slp-gamma chains with pI = 6.55 (Slp-1b). All other inbred strains, bearing H-2j,H-2s,H-2p,H-2d,H-2u, as well as three additional Slp-constitutive wild females captured in Chile, had Slp-gamma chain with pI = 6.71 (Slp-1a).

A polymorphism of the gamma-chain of mouse C4 controlled by the S region of the major histocompatibility complex

Three phenotypes of the gamma-chain of mouse C4 have been detected by a modification of the two-dimensional O'Farrell technique. Strains carrying the H-2s, H-2p, H-2f and H-2ja haplotypes had chains with pI 7.4 (gamma 1). Strains with H-2k, H-2q, H-2d, H-2r, H-2b, H-2u, and H-2w7 had gamma-chains with pI 6.9 (gamma 2), and strains carrying a wild-derived haplotype had gamma chains with pI 6.5 (gamma 3). The genes controlling this polymorphism were mapped in the S region of the H-2 complex by using congenic strains.

A polymorphism of the gamma-chain of mouse C4 controlled by the S region of the major histocompatibility complex

Three phenotypes of the gamma-chain of mouse C4 have been detected by a modification of the two-dimensional O'Farrell technique. Strains carrying the H-2s, H-2p, H-2f and H-2ja haplotypes had chains with pI 7.4 (gamma 1). Strains with H-2k, H-2q, H-2d, H-2r, H-2b, H-2u, and H-2w7 had gamma-chains with pI 6.9 (gamma 2), and strains carrying a wild-derived haplotype had gamma chains with pI 6.5 (gamma 3). The genes controlling this polymorphism were mapped in the S region of the H-2 complex by using congenic strains.

The murine H-2.7 specificity is an antigenic determinant of C4d, a fragment of the fourth component of the complement system

The S region of H-2 controls a polymorphism of the gamma-chain of C4 (gamma 1, gamma 2, and gamma 3) as shown by differences in their isoelectric points. The G region of H-2 was defined by the presence of an alloantigen (H-2.7) on erythrocytes and serum. We found that antisera to H-2.7 immunoprecipitated C4 and no other protein from mouse EDTA-plasma. Furthermore, all H-2.7-positive strains bear C4-gamma 1, and conversely, H-2.7-negative mice bear C4-gamma 2 or gamma 3 (with one exception; see below). The H-2.7 specificity resides on C4d, a 45,000-mol wt fragment generated from the cleavage of the alpha'-chain of C4b by serum control proteins. Because the C4d fragment bears the labile binding site of C4 for cell membranes, it is likely that the erythrocyte alloantigen is acquired from serum as a result of the activation of C4. On the basis of these findings, the existence of a separate G locus is unlikely. Our results also show that C4-gamma 1 and C4-gamma 2 differ from each other at least in their alpha- and gamma-chains, and may represent complex allotypes. No trans effects were observed in F1 hybrids between H-2.7-positive and -negative mice. Mice that bear the k allele in the S region are exceptional in two respects: they are C4-deficient and their C4 molecules bear gamma 2 chains and the H-2.7 alloantigen. Perhaps the low levels of C4 are a consequence of the genetic event leading to this unusual alpha-gamma-chain combination.

Mouse C4 (Ss): three-step purification of its C4c fragment and production of a monospecific antiserum

We report here that a large fragment of mouse C4 (C4c) can be easily purified from serum with good recoveries, and used to produce a monospecific antiserum. The method of isolation of C4c is based on the observation that C4 is easily activated and fragmented in mouse serum. The fragments bind to the C4-binding protein (C4-bp), a newly described macromolecular component of the complement system. The high m.w. complexes were precipitated by dialysis of the serum against 0.1 M acetate buffer, pH 5.0, and purified by passage of the dissolved precipitate through a Sephadex G-200 column. The complexes were dissociated at high salt concentration, and the C4 fragments were isolated by passage of the mixture through a second Sephadex G-200 column. One of the C4 fragments (C4c) was used to immunize rabbits, and a monospecific antiserum was obtained, which showed a reaction of identity between C4 and Slp. Therefore the C4c fragment of C4 and the Slp protein are structurally related.

Structural and functional differences between the H-2 controlled Ss and Slp proteins

Based on functional and structural data, it is concluded that the Ss protein in the mouse expresses the activity of the fourth component of complement. Removal of the Ss, but not of Slp, antigen correlates with a high degree of significance (P less than 0.001) with decrease of C4 hemolytic activity. In phenotypically Slp negative mice the plasma/serum levels of Ss correlate with the C4 activity (P less than 0.001). Structurally, Ss is a 209,000-mol wt protein, consisting of three covalently linked polypeptide chains (alpha,beta,gamma). Treatment of Ss with C1 cleaves a 7,000-8,000-mol wt fragment from the alpha-chain. Slp is also a three chain covalently linked protein of 209,000 daltons, however its three chains differ in size from those of the Ss protein. Slp does not express hemolytic activity and its alpha-chain is not cleaved by C1.

Human C4-binding protein. I. Isolation and characterization

C4-binding protein (C4-bp), a new component of the complement system, was isolated from human plasma by precipitation with polyethyleneglycol, followed by chromatography on ion exchangers. C4-bp was identified on sodium dodecyl- sulfate polyacrylamide gel electrophoresis (SDS-PAGE) by two independent criteria: its ability to bind to C4b, and immunoprecipitation with a monospecificantiserum. Purified C4-bp is a 10.7 s glycoprotein. It consists of several disulfide bonded subunits of mol wt 70,000 daltons. Under nonreducing conditions, its mol wt has been estimated on SDS-PAGE as 540- 590,000 daltons. C4-bp moves as a slow B-globulin at pH 8.6 in the absence of free divalent cations, but when the buffers contain Ca(++)-lactate, C4-bp is a gamma globulin. Purified C4-bp binds to purified C4b. The reaction proceeds in the presence or absence of divalent cations and is not inhibited by diisopropylfluorophosphate. The C4b/C4-bp complexes have sedimentation coefficients between 15 and 17 s on sucrose gradient ultracentrifugation, and can be readily identified by crossed immunoelectrophoresis (CIE). The complexes move faster toward the anode than either protein. C4-bp is multivalent. Saturation is reached at molecular ratios of C4b/C4- bp of between 4 and 5. The interaction between C4b and C4-bp may complicate the electrophoretic patterns of these proteins in normal human serum, if the complement system is activated before or during the run. However, in EDTA-plasma, native C4 and C4-bp do not form stable complexes and can be identified in separate peaks after CIE.

Purificaiton and characterization of mouse serum protein with specific binding affinity for C4 (Ss protein)

A new component of the complement (C).system, with a specific binding affinity for the activated Ss-protein (C4) has been identified in mouse serum. This protein, named Ss- (or C4)-binding protein (Ss-bp), was purified about 200 times from mouse plasma. Ss-bp is a heat stable (56 degrees C, 60 rain) beta-globulin with a sedimentation coefficient in sucrose density ultracentrifugation of 10s. Its concentration in serum of adult male and female mice is 160 and 60 mug/ml, respectively. In EDTA-plasma, Ss and Ss-bp are not associated and can be separated by chromatography in Sephadex G-200. However, in serum Ss-bp binds tightly to Ss. The bonds between these proteins cannot be reversed by chelation of divalent cations. As a consequence of the formation of Ss/Ss-bp complexes, the properties of Ss-bp appear to be quite different in serum of mice with high (Ss-H) or low (Ss-L) levels of Ss-protein. In Ss-H serum, all of Ss- bp is bound to Ss. In Ss-L serum, Ss-bp is mostly free. Because the electrophoretic mobilities of free and complexed Ss-bp are quite different, Ss-bp appears to be polymorphic in serum (but not in EDTA- plasma). The strict dependency of the apparent electrophoretic mobility of Ss-bp on the levels of Ss in serum was demonstrated in a series of congenic mice and among the progeny of a cross between Ss-H and Ss-L strains of mice. Without exception, the slow and fast varieties of Ss-bp were associated with the Ss-L and Ss-H traits. Ss-bp of the slow variety can be transformed into the fast variety by addition of pure human C4, or C4-sufficient guinea pig serum, to Ss-L serum. In both instances Ss-bp formed stable complexes with C4 or a C4- derived peptide. These findings highlight the binding specificity of Ss- bp for the fourth component of the complement system, and in addition they demonstrate a functional homology between the Ss-protein and C4 from two different species.

Comparative haemodynamic effects of dobutamine and isoproterenol in man

Dobutamine was infused at a rate of 8 mcg/kg/min in 17 patients with or without congestive heart failure. Cardiac output increased from an average 2.92 to 4.45 1/min/m2(p less than 0.001) with no change in mean aortic pressure (93.4 to 97.8 mmHg) and only a slight increase in heart rate (78 to 87 beats/min). Left ventricular end-diastolic pressure decreased from an average 19 to 13.7 mmHg (p less than 0.01). Peak left ventricular dp/dt was doubled (1147 to 2370 mmHg/sec, p less than 0.001) and Vmax increased from 1.08 to 2.18 circ/sec (p less than 0.001). In 10 patients given equi-inotropic doses (100 per cent increase in peak dp/dt) Isoproterenol produced a greater increase in cardiac output (71 percent) than Dobutamine /51 percent). Isoproterenol caused mean aortic pressure to fall significantly (8 percent) while no change was noted with Dobutamine. Accordingly, peripheral vascular resistances were reduced to a greater extent with Isoproterenol than with Dobutamine (p less than 0.05). Mean pulmonary arterial pressure decreased significantly (25 +/- 5.9 to 22 +/- 5.7 mmHg, p less than 0.05) with Isoproterenol infusion and remained unchanged with Dobutamine infusion. Dobutamine increased both stroke work (57 percent) and minute work (83 percent). With Isoproterenol however, only minute work was significantly increased (90 percent). Dobutamine therefore is a potent inotropic drug, with mild chronotropic and peripheral vascular effect and may be valuable in the management of severe heart failure not associated with hypotension.

Influence of H-2 on the ontogenesis of a spleen cell population which lacks C3 receptors and Thy-1 antigen

During ontogeny there are marked differences in the cellularity of the spleen of mice from different inbred strains. Data from segregation analysis demonstrate that one of the genes involved in the control of the size of the spleen at 15 days lies in the H-2 region. In contrast to previous reports, we find that the cell population under H-2 influence lacks complement receptors.

[Ultrastructure of spermatogenesis and spermatozoa of Emallagma cheliferum Selys, 1875 (Coenagrionidae: Odonata)]

The spermiogenesis in Enallagma cheliferum follows the usual patterns of differentiation in insects. Thus, the Golgi originates the acrosome; the "nebenkern", the mitochondrial structures that form a long tail with the axonema. The axonema has the configuration 9 + 9 + 2 and around the centriole a centriole adjunt is visible in the immature spermatide. The centriole adjunt differentiates into dense bodies as a "demi-lune" shape in the mature sperm.