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Results for “Complement Pathway, Classical”

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PubMed1980

Kinetic measurement of the interaction of rheumatoid factor with IgG-coated latex particles and the influence of the first component of human complement.

Interaction between isolated rheumatoid factor (RF) of the IgM class or sera from patients with rheumatoid arthritis (RA) and IgG-coated latex particles has been studied kinetically by means of standard aggregometer equipment. The agglutination of particles mediated by isolated RF or RA-sera is inhibited by fresh normal human serum (NHS). The RF-inhibiting principle is heat-labile and recovered in the high molecular weight fractions of NHS separated on a G-200 column. Partially purified first component of complement, C1, also inhibits RF-mediated particle agglutination and disintegrates preformed RF-IgG-latex particle agglutinates. Addition of C1 to heated (56 degrees C, 30 min) NHS restores its RF-inhibiting activity. The most probable basis of this serum activity is competition between C1 with higher affinity for IgG bound to particles and RF. After about 5 min of incubation of NHS with IgG-latex particles the RF-inhibiting activity is gradually lost and interpreted to mean that C1 during the activation of the complement system is discharged from IgG bound to particles. The RF-inhibiting activity of NHS gradually decreases by incubation of serum with increasing doses of activators of the classical complement pathway probably due to the inability of activated C1 to hinder RF-interaction with IgG-particles. The presence in certain RA-sera of C1 in mainly activated form explains why such sera, even if they are fresh are able to agglutinate IgG-particles.

Complement Activation↗
PubMedDate not supplied

[Disturbances of chemotaxis in protein-calorie malnutrition (author's transl)].

A study of specific and non-specific immune functions was performed in 14 children presenting with severe malnutrition, before and after parenteral hyperalimentation by central catheter. Anomalies of cellular functions (reduction of the percentage of E rosettes and deficient proliferation with mitogens) were rarely found. Measurements for serum immunoglobulins did not show any anomaly; however reduced percentages of EAC rosettes and important increase in "null" cells were found in about one third of the cases. The main finding was a decreased serum chemotactic activity following activation of the classic complement pathway. This was found in 12 children and returned to normal values in all cases after hyperalimentation.

Chemotactic Factors↗
PubMed1981

Pseudomonas aeruginosa: quantitation of maximum phagocytic and bactericidal capabilities of normal human granulocytes.

The maximum phagocytic and bactericidal capabilities of normal human PMNs against a seroresistant strain of Pseudomonas aeruginosa were evaluated by morphological observation, uptake of radiolabeled bacteria, and quantitative killing methods. The number of bacteria killed per PMN increased from 3 to 23 as the bacteria-to-PMN ratio was increased from 3:1 to 100:1. Conversely, the percent of bacteria killed decreased from 94% to 3%. In monolayers, an increase in the inoculum from 10(5) to 10(8) cfu/ml was associated with greater phagocytosis and a sixfold increase in PMNs containing greater than or equal to 5 bacteria/PMN. With the use of 75Se-labeled P. aeruginosa, optimal phagocytosis was observed with 10 to 20 bacteria/PMN in 20% NPS. Maximum uptake of 70% occurred in 40 min. No difference was observed in the uptakes of live or heat-killed bacteria. The maximum number of bacteria ingested per PMN was 32 +/- 5 at the highest ratio tested (100:1). The use of altered opsonic sources indicated the need for the classical complement pathway for optimal phagocytosis. Thus study describes the requirements and necessary standardization parameters that were found to be essential for a highly reproducible method for measuring phagocytosis and killing of P. aeruginosa by normal human PMNs. This method could be employed for clinical assessment of partial opsonic or PMN dysfunction in the study of the interaction of PMNs and P. aeruginosa.

Blood Physiological Phenomena↗
PubMed1980

Partial properdin deficiency.

The action of properdin in supporting complement consumption has been investigated in the serum from two individuals with partial properdin deficiency. Our studies are in agreement with those in which serum were artificially depleted of properdin in showing that serum deficient in properdin results in less C3 consumption in the presence of activators of both the alternative and classical complement pathways. Properdin deficiency did not lessen C3 consumption by C3NeF or CoF, confirming that properdin is not necessary for the action of these substances. Our findings indicate that partial properdin deficiency is innocuous but that complete absence of properdin may severely limit one's ability amplify complement activation.

Animals↗
PubMed1981

Characterization of the binding of purified human C1q to heart mitochondrial membranes.

The binding of purified, radioiodinated human C1q to baboon heart mitochondrial membranes was investigated. The interaction of C1q with heart mitochondrial membranes was shown to be readily saturable, specific for C1q, and reversible upon addition of unlabeled C1q or increasing salt concentrations. Scatchard plots of the binding data were biphasic and yielded association constants on the order of 1 X 10(10) and 1 X 10(9) M-1 and binding capacities of approximately 0.16 and 0.24 nmol of C1q/mg of mitochondrial protein. The binding of C1q to isolated cardiac-derived mitochondrial membranes is implicated in the antibody-independent activation of the classical complement pathway by cellular membranes.

Animals↗
PubMed1980

Interaction between Schistosoma mansoni and the complement system: binding of C1q to schistosomula.

In earlier studies we have found that activation of the classical complement pathway (CCP) by the immature schistosomes involves the presence of IgG. By investigating the first step of this activation we have demonstrated in the present work that binding of C1q to schistosomula can occur by two different routes: 1) directly, by specific C1q receptors, and 2) indirectly through the IgG previously attached to Fc receptors present on the parasite surface. Only this second mechanism appears to be involved in CCP activation by schistosomula. Moreover, certain low m.w. schistosome antigens (less than 20,000), which activate CCP, also directly fixed C1q. In this case, IgG are not required for C activation. The presence of receptors for host protein, essentially in 2- to 3-hr-old schistosomula, i.e., the life stage of Schistosoma mansoni that are first in contact with the host, could be the first mechanism by which the schistosomes evade the immune attack.

Animals↗