Contribution of activated C3 to lymphocyte-mediated cytolysis

Klein, Eva; Sármay, Gabriella; Ramos, Olga; Yefenof, Eitan; Gergely, J.

doi:10.1016/0161-5890(86)90161-6

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…lymphocytes. 16 To determine if IL-2 would provide an activating signal similar to that induced by exposure to concanavalin A (Con A) or an alloantigen, PBMC were cultured for 48 hours in medium alone or medium containing 1,000 U/mL rIL-2, the nonadherent cells removed, washed, and then incubated at a density of 2 x lo6 cells/300 pL in GVBS containing purified C3. The culture supernatants were then assayed for iC3b by ELISA and the results expressed as the percentage of C3 fragmented.…”

Section: Normal Pre-days Controls Treatmentmentioning

confidence: 99%

Complement activation in cancer patients undergoing immunotherapy with interleukin-2 (IL-2): binding of complement and C-reactive protein by IL-2-activated lymphocytes

Vachino

Gelfand

Atkins

et al. 1991

Blood

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Plasma samples from cancer patients undergoing immunotherapy with high- dose recombinant interleukin-2 (IL-2) were obtained over a 5-day course of treatment and assayed by radioimmunoassay or enzyme-linked immunosorbent assay for the complement degradation products, C3a, iC3b, Ba, Bb, C4d, and SC5b-9. In the majority of patients, pretreatment C3a, Ba, Bb, and SC5b-9 plasma levels were comparable with those measured in normal donor plasma. However, by the end of the 5-day treatment course, C3a levels had increased 15.6-fold. In several patients, peak concentrations of C3a were as high as those reported in patients with sepsis or burn injury. Plasma levels of alternative pathway components Ba and Bb also increased, 8.0- and 5.0-fold, respectively, during IL-2 treatment. Likewise, levels of one of the terminal complexes, SC5b-9, increased 5.0-fold and the plasma C4d and iC3b concentrations increased 4.8- and 2.9-fold, respectively, by the fifth day of treatment. To determine whether activated lymphocytes participate in IL-2-induced complement activation, peripheral blood mononuclear cells (PBMC) obtained from IL-2 recipients before and 5 days after beginning therapy were reacted with monoclonal antibodies (MoAbs) against C3c and the terminal complement complex SC5b-9. Dual-color cytofluorographic analysis showed that within the CD3(+) population, the percentage of cells binding the anti-C3c and anti-SC5b-9 MoAbs increased 6.2-fold and 5.1-fold, respectively, by day 5. The anti-C3c MoAb also bound to CD3(+) cells stimulated in vitro with IL-2 and then exposed to serum. Moreover, fluid-phase iC3b was generated from purified C3 by PBMC activated in vitro with IL-2, but not by unstimulated cells. Serum levels of C-reactive protein (CRP) are markedly elevated in patients undergoing IL-2 immunotherapy. This hepatic acute phase reactant has been shown to activate the classical pathway when bound to cell surfaces. Because levels of the classical component C4d increase markedly during IL-2 treatment, we sought to determine if CRP became bound to PBMC during IL-2 treatment and found that during therapy, the percentage of CD3(+) cells reactive with an anti-CRP MoAb increased from less than 2% to greater than 18%. When PBMC were activated with IL- 2 in vitro and then exposed to exogenous CRP, greater than 20% of the CD3(+) cells reacted with the anti-CRP MoAb.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Normal Pre-days Controls Treatmentmentioning

confidence: 99%

Complement activation in cancer patients undergoing immunotherapy with interleukin-2 (IL-2): binding of complement and C-reactive protein by IL-2-activated lymphocytes

Vachino

Gelfand

Atkins

et al. 1991

Blood

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“…Earlier experiments have shown that ex pression of CR2 molecules is a prerequisite for C3 fragment fixation following ACP acti vation by B cell lines. Lymphoid cell lines that did not express CR2 did not fix C3 frag ments [7], In addition, removal of CR2 by mild trypsin treatment or antibody-me diated shedding temporarily abrogated the C3-binding capacity, until CR2 molecules reappeared on the membrane [15]. Contrary to the expectation, the majority of the fixed The C3-activating cells, with the excep tion of BL28 and Ramos, were resistant to lysis by the membrane attack complex.…”

Section: C3 Fragment Binding By the B Cell Linesmentioning

confidence: 43%

Activation and Fixation of C3 by Human B Cell Lines Is Enhanced by Interferon-Gamma and Tumor Necrosis Factor Alpha

Yefenof¹,

Algarra²,

Ramos³

et al. 1991

Complement Inflamm

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Human B cell lines were tested for the capacity to convert C3 to C3b/iC3b through the alternative C pathway (ACP) and to fix the generated C3 fragments. The panel of lines included four Epstein-Barr virus (EBV)-negative Burkitt’s lymphomas and their sublines converted with two EBV strains: the prototype B958 (B virus) and the nontransforming P3HR-1 (P virus). Comparison of these groups of parallel lines (derived from a single patient) showed that the EBV-carrying cells were more efficient in activation and fixation of C3. All cell lines activated C3 with higher efficiency when treated with interferon gamma or tumor necrosis factor alpha. After treatment, the comparative relationships between the sublines changed. The treated EBV-negative and the P virus converted sublines showed similar levels of ACP activation, while the B virus carrying sublines were more efficient. The amounts of bound C3 fragments on the activating cells correlated with the ACP efficiencies. In accordance with the elevated ACP activation capacity of the cells after cytokine treatment, the amounts of C3 fragments detected on their surfaces were higher. Among the lines tested, only two (BL28 and Ramos) were sensitive to C-mediated lysis. The lytic sensitivity of these two lines increased after treatment with the cytokines. The results indicate, therefore, that the cytokine-induced increase in ACP activation by Burkitt’s lymphoma lines is not sufficient to overcome resistance to C lysis.

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“…Conversion of fixed C3b to iC3b is one of the steps of the escape. However, iC3b can bind to CR3 and thereby bridge opsonized targets with NK cells and macrophages [35]. If the cells are sensitive to the damage mediated by these effectors the bridge potentiates the interaction.…”

Section: Discussionmentioning

confidence: 99%

Expression of the complement regulatory proteins CD21, CD55 and CD59 on Burkitt lymphoma lines: their role in sensitivity to human serum‐mediated lysis

Kuraya

Klein

et al. 1992

Eur J Immunol

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Expression of the complement regulatory proteins CD21, CD55 and CD59 on Burkitt lymphoma lines: their role in sensitivity to human serum-mediated lysis* On a panel of nine human B cell lines we showed that the expression of the complement regulatory factors complement receptor type 2 (CR2; CD21), decay-accelerating factor, (DAF; CD5.5) and homologous restriction factor (HW20, CDS9) is not correlated. All lines expressed DAF, six lines carried detectable amounts of CR2 and three carried HRF20. Upon incubation in human serum, under conditions which allowed the activation of complement through the alternative pathway, the CR2-carrying lines bound C3 fragments and two of them (Ramos and one of its two sublines) were damaged.These two lines had the lowest DAF expression, less than SO % of the cells reacted with the IAlO monoclonal antibody. By modulating the expression of the complement regulatory molecules, the lytic sensitivity of the B cell lines could be altered. Blockade of DAF on the HRF20-, CR2+ lines with the specific monoclonal antibodies increased their sensitivity to lysis by human serum. With the DAF-and HRF20+ cells significant lytic effect was obtained only when they were pretreated with both of the specific antibodies. Interferon-y or tumor necrosis factor-a treatment elevated the amount of CR2 on the low-CR2 expressor line (RamodHRlK) which thereafter bound higher amounts of C3 fragments and was lysed when incubated in human serum.This line had relatively low DAF level and lacked HRF20. The cytokine treatment did not alter the expression of these molecules. The CR2+ Ramos and the CR2-Rae1 cells were treated with 5-azacytidine which induced HRF20 and increased DAF expression. In parallel with this change Ramos cells became resistant to C-mediated lysis. The experiments with the panel of human B cell lines showed thus that cytolysis through activation of complement in homologous serum can be regulated at several steps by cell surface molecules.While expression of CR2 was required for C3 fixation, DAF and HRF20 inhibited lysis. By independent modulation of the quantities of these molecules, cells acquired or lost their sensitivity. IntroductionThe complement (C) cascade can be initiated by the classical and by the alternative pathways. In both events C3, the key molecule, is split to C3a and C3b, and C3b is fixed on the activating surfaces. In the alternative C pathway (ACP), C3b forms C3 or C5 convertases with activated factor B (Bb).The end product of the C cascade is the CSb-9 membrane attack complex (MAC), which can The C regulatory factor DAF (CD55), first detected on erythrocytes prevents the assembly of C3 convertases by dissociating Bb from the fixed C3b [7-101 .The C regulatory factor CD59 was discovered independently by several investigators. It was termed 20-kDa homologous restriction factor (HRF20) [11-141, P-18 [15] and membrane inhibitor of reactive lysis (MIFU) [16]. It prevents the CSb-8 complex-mediated C9 insertion into the cell membrane 1171.The significance and the function of these C...

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Contribution of activated C3 to lymphocyte-mediated cytolysis

Cited by 8 publications

References 11 publications

Complement activation in cancer patients undergoing immunotherapy with interleukin-2 (IL-2): binding of complement and C-reactive protein by IL-2-activated lymphocytes

Complement activation in cancer patients undergoing immunotherapy with interleukin-2 (IL-2): binding of complement and C-reactive protein by IL-2-activated lymphocytes

Activation and Fixation of C3 by Human B Cell Lines Is Enhanced by Interferon-Gamma and Tumor Necrosis Factor Alpha

Expression of the complement regulatory proteins CD21, CD55 and CD59 on Burkitt lymphoma lines: their role in sensitivity to human serum‐mediated lysis

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