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PubMed1984

Allotypes of murine factor B controlled by a locus within the S region of the H-2 complex.

Bf protein was directly precipitated from a mixture of EDTA-plasma from 13 different, inbred strains and rabbit IgG anti-mouse Bf, and was isolated by SDS-PAGE. The gel pieces containing Bf protein were digested by trypsin after labeling with 125I-Na, and then peptides of Bf protein with each mouse strain were compared by two-dimensional peptide mapping. The results for the peptide patterns with the standard B10 congenic strains (all of which Bf phenotypes had been already designated as Bf.1 because of the identical isoelectric point values) revealed two distinct peptide patterns. The peptide pattern of Bf protein appeared to be identical in each of the inbred strains, but only one of the 36 spots in the fingerprint observed either with B10 or B10.BR (designated tentatively as Bf.1 (b.k.) ) was not detected in that from B10.D2 and B10.S (designated tentatively as Bf.1 (d.s.) ). The results of peptide mapping with intra-H-2 recombinant inbred strains show that this structural variant was mapped to the S region, which is direct evidence that allotypes of murine Bf are encoded by a structural gene within the MHC.

Animals↗
PubMed1984

An unusual "morphologic" variant of BF S.

In the course of family studies of haplotypes of the alleles of the sixth chromosome loci HLA-A, C, B, D/DR, BF, C2, C4A, C4B, and glyoxalase I, we encountered an unusual BF variant. Its mobility was similar to BF F but it appeared to have a lesser intensity after straining with Coomassie Blue, and it was demonstrated by crossed immunoelectrophoresis to be present in lower concentration. It was therefore designated BF FQL. This variant was found on the haplotype HLA-A1, B17, DR7, BF*FQL, C2*C, C4A*6, C4B*1, GLO2. All other haplotypes of this type so far identified carry the BF variant BF S. Following activation of serum samples with zymosan, BF was analyzed by both agarose electrophoresis and isoelectric focusing and immunofixation. On both treatments, serum with BF SFQL produced a Ba pattern identical to that of a sample which was BF S. The Bb pattern for F and S are similar but differ from those of the rare variants BF F1 and BF S1. The Bb pattern of BF FQL was, thus, as expected, the same as BF F or BF S. Hence, we conclude that the variant is a mutant from BF S with mobility similar to BF F. The mutation seemed also to have resulted in a lower concentration of product than normal.

Chromosome Mapping↗
PubMed1983

Activation of C1 by soluble IgG aggregates as detected by a novel one-step hemolytic assay that specifically measures the proenzyme form of C1s.

A new hemolytic assay is described that specifically measures the precursor form of the C1s subcomponent of the complement system. The assay employs a C1s-depleted reagent obtained by immunoadsorption of fresh human plasma on immobilized goat anti-human C1s antibodies. Linear Z plots are obtained with nanogram levels of precursor C1s, whereas C1s completely fails to induce hemolysis in the assay. Because low concentrations of C1s do not interfere with the activity of precursor C1s, the assay can be used for the stoichiometric measurement of C1 activation. The precursor C1s assay was applied to the study of C1 binding and activation by soluble aggregates of human IgG (AIgG). Incubation of purified human C1 with AIgG caused a temperature-independent consumption of whole C1 hemolytic activity, indicating binding of C1, but almost no consumption of the total (precursor + activated) C1s activity. On the other hand, activation of C1, measured as the time- and temperature-dependent consumption of precursor C1s, could greatly exceed the binding of C1. These findings can be explained by using recent findings concerning the association-dissociation equilibrium between C1q and the tetrameric complex of C1r and C1s.

Animals↗
PubMed1983

In vivo instability of red-blood-cell-bound C3d and C4d.

Until now, there have been no measurements of the in vivo stability of red-blood-cell-bound C3d and C4d subfragments of the third and fourth components of human complement. We have recently described a radiolabeled antiantiglobulin method for measuring RBC-bound C3d and have demonstrated that small amounts of C3d are present on RBC of all normal subjects tested. In the present study, the method was applied to follow the increments above baseline of RBC-bound C3d and C4d produced by autotransfusing 3 normal volunteers with 160-200 ml of RBC strongly coated in vitro by C3d and C4d. Posttransfusion measurements were carried out over 21-34 days. Immediate and long-term in vivo survival of the transfused RBC was unimpaired by C3d and C4d coating. Of the bound C3d antigen, 85%-95% disappeared from circulating RBC in 5-8 days; the remainder disappeared more slowly, with half-times in the range of 8-29 days. C4d antigen disappeared substantially more slowly, describable by a single exponential function in 2 of the 3 subjects, with half-times in the range of 12-31 days. Recognition of the in vivo instability of RBC-bound C3d helps in interpreting steady-state and changing levels of RBC C3d coating in a variety of alloimmune and autoimmune disorders.

Adult↗
PubMed1984

Plasma lactoferrin reflects granulocyte activation via complement in burn patients.

Complement activation and neutropenia have been observed in thermally injured animals. In burn patients, granulocyte chemotaxis and morphological loss of specific granules occur. We conjectured that complement is activated in humans and, in turn, induces granulocytes to secrete lactoferrin (LF), a marker of granulocyte activation. Twenty burn patients were evaluated for absolute granulocyte count (AGC), plasma levels of anaphylatoxins (C3a, C4a, C5a), and lactoferrin. The AGC directly correlated with the extent of the burn on day 1. Similarly, plasma LF on day 1 correlated with the percent burn. Those with greater than 30% burn had plasma LF between 10 and 40 micrograms/ml (normal LF = 1.5 +/- 1.8 micrograms/ml). In five patients without further complications followed serially, plasma LF did not return to normal until 2 to 5 weeks. In all patients, there was evidence of complement activation; C4a ranged between 283 and 13,064 ng/ml and C3a between 19 and 852 ng/ml. In some patients, C5a was detectable, but the values correlated inversely with the extent of burn. On the other hand C3a and C4a levels did not correlate with the extent of burn but threefold to fivefold rises of C3a levels on days 7 and 9 predicted gram-negative sepsis. Although plasma LF did not predict sepsis, levels greater than 12 micrograms/ml on day 1 heralded the onset of neutropenia on day 3 in 60% of patients with 30% burn. Six of 20 patients developed pulmonary radiographic changes and, in five of the six, the changes occurred by day 3. Plasma LF in all six patients on day 1 was greater than 17 micrograms/ml. In two patients with greater than 50% burn, depletion of granulocyte LF was demonstrated histochemically. These studies indicate that complement is activated in burn patients, which is associated with granulocyte secretion. Measurement of plasma anaphylatoxins and LF may serve as useful aides in clinical management of these patients.

Adult↗
PubMed1983

Activation of complement by leptospires and its bactericidal activity.

Bactericidal activity of complement was found to be effective on saprophytic Leptospira biflexa strains and not on Leptospira interrogans strains, by means of viable counting; the killing effect on saprophytic strains was probably due to a direct activation of the complement system via the alternative pathway. On the contrary the pathogenic strains seemed to activate the complement at a lower extent and were, in any case, resistant to the lytic action of the activated complement.

Animals↗
PubMed1984

[Serum complement and immunoglobulins in patients with common migraine].

Research has already been conducted into complement, immunoglobulin, and immune complexes with regard to analogies with allergy mechanisms (in the case of dietary headaches) or with vasculitic alterations. The results showed no complement activation or variation in the immunoglobulin of migraine sufferers during healthy intervals and migraine attacks that in any way support an involvement of the immune system in the pathogenesis of common migraine.

Adolescent↗
PubMed1983

Complement activity in the cord blood of term neonates with the amniotic fluid infection syndrome.

Cord blood samples from 11 term neonates whose placentas showed histological changes typical of the amniotic fluid infection syndrome were analysed in order to determine haemolytic activity of the classic and alternative complement pathways and serum levels of complement proteins and immunoglobulins. Although the mean values of all these parameters were higher in this group than in an age-related control group, only classic haemolytic pathway activity was significantly elevated (P less than 0,025).

Amniotic Fluid↗