The septic burned patient: a model for studying the role of complement and immunoglobulins in opsonization of opportunist micro-organisms

Studies were performed to determine the effects of septicemia on complement levels and activities and opsonic function in septic and nonseptic burned patients. None of the nonseptic burned patients had consumption of classical pathway activity during their clinical course. Patients who did not survive septicemia had consumption of all of the classical complement components (C1-C5) prior to and during their septic episodes. Patients who survived septicemia had multiple patterns of classical complement pathway consumption. In these patients, classical pathway activity was restored to normal following the last positive blood culture. Alternative complement pathway consumption was demonstrated in only one of the septic burned patients, as evidenced by decreased factor B and C3b INA levels and decreased C3 and C5 conversion in sera treated with 10 mM ethylene glycol tetraacetic acid and 10 mM MgCl(2) (MgEGTA) and in untreated sera. In all of the other septic patients and in the nonseptic patients, reduction in C3 and C5 conversion in MgEGTA sera and untreated sera was not associated with decrease in factor B or C3b INA. Reduction in complement levels and activities did not reduce the ability of the patients' sera to promote phagocytosis and intracellular killing of their infecting micro-organisms by normal human peripheral polymorphonuclear leukocytes. The results indicate that measurement of classical pathway activity in burned patients can be used as a diagnostic tool for predicting the severity of septic episodes and for monitoring recovery. In addition, the observation that complement consumption did not reduce the opsonic capacity of the patients' sera for their infecting micro-organisms suggests that current concepts regarding the role of immunoglobulins and complement in opsonization of opportunist micro-organisms require re-evaluation.

Evidence for glomerular modulation of complement activation

Using indirect immunofluorescence, three regulatory proteins of the complement system, C1-inhibitor (C1-INH), C3b inactivator (C3bINA) and beta 1H globulin have been detected in the glomeruli of patients with glomerulonephritis associated with complement activation. C1-INH and beta 1H were found frequently but C3bINA was rarely detected (only 14 biopsies). beta 1H globulin and C3b inactivator which modulate C3b activity were never found in the absence of C3, but C1-INH was sometimes found in the absence of C1s. The patterns for staining for C1s and C1-INH, C3 and beta 1H were almost identical suggesting that the regulatory proteins are binding to the proteins they regulate, as has been demonstrated in vitro. Thus, in tissues undergoing complement-mediated tissue damage, the extent of complement activation is controlled by the normal regulatory mechanisms.

Demonstration of beta 1H globulin together with C3 in the dermal-epidermal junction of patients with systemic lupus erythematosus

Skin lesions and clinically normal skin from 10 patients with systemic lupus erythematosus (SLE) were examined by immunofluorescence for the presence of C3 and its control protein, beta 1H globulin. beta 1Hwas always found in association with deposited C3; in the instance where C3 deposits were not found beta 1H was also not found. Granular deposits of C3 and beta 1H were found in the dermal-epidermal junction (DEJ) in all of the 5 nonlesional skins studied. In the lesional skin, C3 was found in 4 of 5; in 2 of these 4, beta 1H was also found. As previously demonstrated for in vitro systems, beta 1H also binds in vivo to fragments of C3, presumably C3b, generated during activation of the complement system.

Possible C1q bypass loop activation in the haemolytic uraemic syndrome

Ultrastructural and immunofluorescent microscopic studies were performed on renal tissue obtained from nine patients during the acute and convalescent phase of the haemolytic uraemic syndrome (HUS). All had glomerular deposits of IgM in the absence of circulating immune complexes. This was associated with deposition of C1q during the acute phase, and properdin and C3 during the convalescent phase. C4 was consistently absent. Since such a pattern of complement deposition does not fulfil criteria either for alternate or classical pathway activation, the possibility of C1q bypass loop activation by IgM is suggested.

Modulation of the properdin amplification loop in membranoproliferative and other forms of glomerulonephritis

The mean serum concentrations of C3b inactivator (C3bINA) and beta1H globulin were measured in eighty-six sera (thirty-five membranoproliferative, thirteen membranous, thirty-one focal and seven minimal change) taken from seventy-five patients with histologically diagnosed glomerulonephritis. In none of the four groups of sera did the mean concentrations of both these proteins differ significantly from the mean levels in a group of fifty normal sera. However, in the membranoproliferative group, the mean level of C3bINA, but not beta1H, was significantly lower in the nephritic factor positive than in the nephritic factor negative group. When the eighty-six sera were considered together, serum concentrations of C3bINA and beta1H correlated with levels of C3, factor B, properdin and C4. When the membranoproliferative group was considered separately, C3bINA levels correlated with levels of C3, factor B, properdin and C4 and beta1H correlated with C3 and factor B, but not properdin or C4 in the nephritic factor negative group, but no such correlations were observed in the nephritic factor positive group. The significance of these findings is discussed in the light of current thoughts on the mechanisms of modulation of the alternative pathway.

Experimental bovine trypanosomiasis. Changes in serum immunoglobulins, complement and complement components in infected animals

In three calves experimentally infected with Trypanosoma congolense the amounts of IgG1 and IgG2 were little changed and similar to those of normal animals. IgM increased in amount early in the infection and the amount of the increase appeared related to the parasite burden. The amounts of IgA and IgE were both much decreased and this also appeared related to the numbers of parasites in the blood. There was a decrease in the amounts of total haemolytic complement and complement components C1, C1q and C3 in the infected calves. Furthermore the amounts of properdin fluctuated with the cyclical changes in numbers of T. congolense parasites in the individual calves. No significant change in the amount of C8 was observed. It is considered that activation of both the alternative and the classical complement pathways occurs in trypanosome infected animals but that neither pathway goes to its terminal stages.

[Nonspecific resistance in germ-free and E. coli monocontaminated miniature piglets]

Phagocytic activity of leukocytes, as well as the complement, properdin, and lysozyme levels in the blood serum of miniature piglets, germfree and monocontaminated with E. coli 055 and E. coli 083, were studied. E. coli 055 phagocytosis was decreased in the presence of autologous serum and complement and increased under the effect of specific opsonins (antibodies to E. coli 055). Complement, properdin, and lysozyme levels were decreased in the germfree, in comparison with conventional animals. In the E. coli contaminated piglets properdin and complement production was stimulated most, and lysozyme formation--less. No antibodies to E. coli 055 were revealed in monocontaminated piglets. The highest lysozyme levels were found in the ex-germfree animals, this indicating the participation of factors other than E. coli contamination in lysozyme stimulation. It is concluded that microbial contamination played an important role in the development of cellular and humoral factors of the organism resistance.

Host defense against opportunist microorganisms following trauma. II. Changes in complement and immunoglobulins in patients with abdominal trauma and in septic patients without trauma

Total hemolytic complement (CH50), conversion of C3 by inulin and cobra venom factor (CoVF), and immunochemical levels of Clq, C4, C2, C3, C5, factor B, properdin, C3b inactivator (KAF), and immunoglobulins (Igs) G, A, and M were measured in the sera of ten patients with abdominal trauma and ten medical patients with septicemia without trauma. Reduction in C3 conversion by CoVF and decrease in the levels of properdin and KAF were demonstrated in the trauma sera. CH50 and the level of C5 were also decreased. Conversion of C3 by inulin and levels of factor B, Clq, C4, C2, and C3 were found to be normal in the patients' sera. Complement levels and activities were found to be normal in the sera of the septic non-trauma patients. A decrease in serum IgM was observed in both patient groups; levels of IgG and IgA were normal. These results indicated that abnormalities of immunoglobulin and of the alternative and classical complement pathways were associated with nonburn trauma. Moreover, the data suggested that consumption of the classical complement pathway associated with septicemia in the thermally injured patient resulted from synergism between the trauma and infection rather than from septicemia per se.

Host defense against opportunist microorganisms following trauma. I. Studies to determine the association between changes in humoral components of host defense and septicemia in burned patients

Total hemolytic complement (CH(50)), conversion of C3 by inulin, and immunochemical levels of Clq, C4, C2, C3, C5, factor B, C3b inactivator (KAF), and properdin were measured in the sera of 15 patients with severe thermal injury during nine weeks postburn. Five of the 15 patients had multiple episodes of septicemia as documented by positive blood cultures and clinical findings. Decrease in CH(50), Clq, C4, C2, C3, and C5 occurred prior to and during septic episodes in these patients. Although conversion of C3 by inulin was often reduced during septic episodes, levels of factor B and KAF were generally normal or elevated. In only one patient did consumption of complement occurring during septicemia decrease the opsonic capacity of the patient's sera for the patient's infecting microorganism, an isolate of E. coli; sera from the same patient opsonized her infecting strain of S. aureus normally. The microorganisms isolated from the other septic patients, which were opsonized normally by the patients' sera despite complement consumption, were also with one exception strains of Staphylococci. In the nonseptic burned patients, decrease in properdin and C3 conversion by inulin, and increase in C3, factor B and KAF were demonstrated as we have previously reported. The results indicate that the classical complement pathway was activated during septicemia in burned patients and that activation of this pathway occurred preferentially due to inhibition of the alternative pathway. In addition, the data show that complement consumption may reduce the opsonic capacity of a patient's sera for certain microorganisms and not for others.

Serum complement components in Henoch-Schönlein purpura

Serum levels of C1q, C4, C3, C5, factor B, and properdin were measured in patients with Henoch-Schönlein purpura (HSP). In the cases of acute HSP, 9 of 23 (39%) had a low CH50, and 5 of 17 (30%) a low properdin; C1q, C4, and C3 levels were not depressed. In 10 cases with chronic nephritis following HSP, complement components were normal except for 2 with reduced C4 and one with low properdin. These findings confirm that complement activation occurs in HSP; the low serum levels of properdin in the acute group indicate that there is activation of the alternative pathway in these patients.

[Properdin in the lymph in traumatic stress]

The changes of properdin level in different kinds of lymph and blood of dogs in case of burn of hind paws (the 1st group), and of craniocerebral injury (the 2nd group) were investigated. The properdin level proved to increase in the lymph of the cervical duct and the afferent lymph of the popliteal node in both the groups of dogs. The properdin level in the afferent lymph of the popliteal lymph node, thoracic duct and in blood was reduced in case of the burn and rose in cranicerebral injury. The total protein level in the afferent and efferent lymph of the popliteal lymph node, the cervical and thoracic ducts rose, whereas the total blood protein level fell.

Complement levels in pneumococcal pneumonia

Levels of complement proteins and functional activity of the alternate complement pathway were assessed in 39 patients with pneumococcal pneumonia. Mean levels of C3 and properdin and the functional activity of the alternate pathway in acute sera were significantly (P less than 0.05) below normal, whereas levels of components of the early classical pathway were normal. Although levels of factor B were in the normal range, they correlated significantly with C3 levels; there was no significant relation between C3 levels and C4 or C1q levels. The 19 patients iwth pneumococcal pneumonia and bacteremia had significantly lower mean values of properdin and factor B than the 20 patients without bacteremia, suggesting a more severe depression of the alternate complement pathway with bacteremia. During convalescence, complement levels were normal or elevated in most of the patients, but mean levels of properdin remained significantly below normal in bacteremic patients. Functional activity of the alternate pathway also remained below normal. These results indicate that there is a selective depression of the alternate pathway in patients with pneumococcal pneumonia, and they are consistent with the concept that the alternate pathway has an important role in host defenses in pneumococcal infection.