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PubMedDate not supplied

Another look at the nephrotic syndrome in adult Nigerians: pathological and immunological findings.

One hundred and twenty adult Nigerians with the nephrotic syndrome were subjected to similar pathological investigations which included light microscopy and immunoperoxidase study of renal biopsy specimens, serum immunoglobulins and C3c levels. Histological findings showed a wide range of changes with the minimal change type of lesion and proliferative glomerulonephritis accounting each for 33.3 percent of cases studied. Focal changes accounted for 26.3 percent of cases. Glomerular immune deposits were present in 78.6 percent of cases showing non-minimal change glomerular lesions. Serum IgG and IgA were significantly depressed when compared with matched controls (P less than 0.05 and P less than 0.01 respectively) while IgM levels were significantly increased, (P less than 0.001). There was no significant difference between the mean values of serum C3c in the nephrotic group and matched control group. This study shows the high incidence of minimal change nephropathy in our adult population. Although some immunoglobulin (especially IgM) may be identified in occasional glomeruli and cause uncertainty as to the diagnosis, such minor deposition of IgM which is often non specific does not preclude a diagnosis of minimal change nephropathy.

Adolescent↗

PubMed2005

Complement 4 levels as early predictors of poor response to surfactant therapy in respiratory distress syndrome.

The aim was to determine whether stronger complement activation is an early predictor of poor response to surfactant treatment in infants with severe respiratory distress syndrome (RDS). Thirty-one preterm newborns with severe RDS (initial fraction of inspired oxygen [FiO (2)] > 0.5) and 22 healthy preterm newborns were studied. The study group was divided into two subgroups according to their response to natural surfactant 6 hours after administration: good responders had reduction in FiO (2) > 50% of the presurfactant level, and poor responders had a reduction in FiO (2) < or = 50%. Levels of complement 4 (C4) and C3c were measured in blood samples drawn at admission and 24 hours after birth. The poor responders to surfactant had significantly lower serum C4 levels at admission and in the first day of life than the good responders. The poor responders also had lower C3c levels at birth than the good responders, but higher C3c levels at 24 hours. Receiver-operator curve analysis revealed that, compared with C3c at admission, C4 at admission was a more sensitive and specific predictor of poor response to surfactant treatment in preterm newborns with severe RDS (area under the curve, 0.863; 95% confidence interval, 0.726 to 1; p = 0.001). Significantly decreased serum C4 at admission is a valuable early predictor of poor response prior to surfactant treatment in preterm newborns with severe RDS. C4 level may help investigators determine the mechanisms underlying poor responsiveness to surfactant.

Biological Products↗

PubMedDate not supplied

[Demonstration and differentiation of circulating immune complexes in chronic inflammatory rheumatic diseases using a semiautomated PEG-precipitation laser nephelometer test].

Circulating immune complexes were determined in rheumatoid arthritis and systemic lupus erythematosus using a semiautomated PEG-precipitation laser-nephelometer technique. Immunoglobulins IgA, IgG and IgM as well as complement proteins C3c and C4 were quantitatively determined in 2.75% PEG-precipitates. The PEG-precipitates obtained from the sera of healthy controls, SLE patients, and RA subjects displayed different protein patterns. In RA sera a significant elevation of all investigated proteins was found. In SLE sera, a significant increase of IgG, IgA, IgM, and C3 was found, whereas C4 was significantly reduced as compared to the controls. Typical values for a calculated IgG/C4 ratio in circulating immune complexes were obtained for RA and SLE. In RA this ratio remained unchanged in different activity stages and was found in seropositive as well as in seronegative sera. Thus circulating immune complexes from SLE and RA sera differ with respect to the degree of complement-dependent solubilization.

Adult↗

PubMed1998

Differences in glomerular leukocyte infiltration between IgA nephropathy and membranoproliferative glomerulonephritis.

BACKGROUND: An important aspect in glomerular nephritic processes is the enhanced influx of leukocytes into the glomerulus. METHODS: To investigate the mechanisms of intraglomerular leukocyte infiltration in IgA nephropathy (IgA-N) and membranoproliferative glomerulonephritis type I (MPGN-I), we immunohistochemically examined the intraglomerular expression of leukocyte function-associated antigen-1 (LFA-1, CD11a/CD18), macrophage-1 (Mac-1, CD11b/CD18) and intercellular adhesion molecule-1 (ICAM-1, CD54) together with glomerular deposition of C3c and fibrinogen. RESULTS: In IgA-N (n=42), LFA-1+ cells were distributed mainly in glomeruli with intense expression of ICAM-1, and there was a positive correlation (P<0.001) between the number of LFA-1+ cells and the degree of ICAM-1 expression. Mac-1+ cells had no correlation with glomerular C3c deposition, but had a significant correlation with fibrinogen deposition (P<0.05). The number of LFA-1+ cells was significantly greater than of Mac-1+ cells (P<0.05). The number of LFA-1+ cells was strongly correlated with that of CD68+ cells (P<0.00001). In MPGN-I (n= 43), on the contrary, Mac-1+ cells correlated only with C3c deposition (P<0.001), and they were observed mainly in peripheral loops of glomerular capillaries where C3c was deposited with a similar distribution. However, there was no relationship between LFA-1+ cells and ICAM-1 expression. The number of Mac-1+ cells was greater than that of LFA-1+ cells (P<0.0001), and most Mac-1+ cells were identical to CD15+ cells. CONCLUSION: These results indicate the possibility that different mechanisms may cause glomerular leukocyte infiltration in various forms of human glomerulonephritis. The LFA-1/ICAM-1 pathway may play an important role in glomerular leukocyte infiltration in IgA-N, while the Mac-1/complement pathway may be important in MPGN-I. The former may promote mainly the infiltration of CD68+ cells, and the latter may promote that of CD15+ cells. In addition, Mac-1+ cells may act as fibrinogen and complement receptors in IgA-N and MPGN-I, respectively.

Antigens, CD↗

PubMed2000

Prevention of infection in multiple trauma patients by high-dose intravenous immunoglobulins.

OBJECTIVE: To investigate the activity of intravenous immunoglobulin (IVIG) as a prophylactic agent against infection in trauma victims. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: A 20-bed university intensive care unit. PATIENTS: Thirty-nine trauma patients with injury severity scores (ISSs) of 16-50. INTERVENTIONS: Penicillin was given at the time of admission and continued at least until day 4. Twenty-one patients received IVIG and 18 patients received human albumin at 1 g/kg in four divided doses (days 1, 2, 3, and 6). The two groups had similarities in age, gender, Acute Physiology and Chronic Health Evaluation II score, risk of death, and Glasgow Coma Scale score, but differing ISSs (p = .02), at the time of admission. Blood was collected on days 1, 4, and 7. MEASUREMENTS AND MAIN RESULTS: Clinical variables related to infection were recorded. The complement components C3c, C4 and CH50, IgG, and the fractions of IgG were measured. The serum bactericidal activity (SBA) was assessed at 37 degrees C (98.6 degrees F) and 40 degrees C (104.0 degrees F) at the time of admission and during the course of IVIG administration. Controlling for ISS, IVIG-treated patients had fewer pneumonias (p = .003) and total non-catheter-related infections (p = .04). Catheter-related infections (p = .76), length of stay in the intensive care unit, antibiotic days, and infection-related mortality did not differ between the two groups. A significantly increased trend in IgG and its subclasses was shown on days 4 and 7 in the IVIG group but not in the control group (p<.000001). No important differences were noted in complement fractions. The SBA of the groups was similar on day 1, but significantly higher on days 4 and 7 (p<.000001) in the IVIG group, remaining so controlling for complement and ISS. SBA was higher at 40 degrees C (104.0 degrees F) compared with 37 degrees C (98.6 degrees F) (p<.0001) under all three conditions. In both groups, low SBA (on days 1, 4, and 7) was associated with increased risk of pneumonia (p<.01) and non-catheter-related infections (p = .06 for day 1; p<.01 for days 4 and 7). CONCLUSIONS: Trauma patients receiving high doses of IVIG exhibit a reduction of septic complications and an improvement of SBA. Early SBA measurement may represent an index of susceptibility to infection.

APACHE↗

PubMed1993

Endotoxin-induced pulmonary dysfunction is prevented by C1-esterase inhibitor.

In septic shock, hypotension, disseminated intravascular coagulation, and neutrophil activation are related to the activation of the blood coagulation contact system. This study evaluates in dogs the effect of the C1-esterase inhibitor (C1-INH), a main inhibitor of the blood coagulation contact system, on the cardiovascular and respiratory dysfunction associated with endotoxic shock. Two groups were included: controls, which received Escherichia coli endotoxin, and a C1-INH group in which C1-INH was infused before E. coli endotoxin administration. In both groups, endotoxin produced hypodynamic shock; however, the decrease in the systolic index and the ventricular systolic work indexes were greater in controls than the C1-INH group. In controls, the arterial O2 partial pressure decreased by 30% and the alveolo-arterial O2 difference increased by 625%, these parameters remained unchanged in the C1-INH group. Hypoxemia was associated with increased intrapulmonary shunt, decreased blood coagulation contact factors, and decreased C3c. In contrast, C1-INH administration prevented endotoxin-induced hypoxemia, the increase in intrapulmonary shunt, and the decrease in blood coagulation contact factors. This study shows that, in dogs with endotoxic shock, pulmonary dysfunction is associated with an activation of the blood coagulation contact phase system. An inhibition of this system by C1-INH prevented the hypoxemia induced by endotoxic shock.

Animals↗

PubMed1997

Immunoglobulin and C3-activator profile of the microbiology laboratory worker.

The levels of immunoglobulin, C3-Activator and C3c in the sera of members of staff who have been continuously engaged for upwards of 10 years in the microbiological routine laboratory of a teachings hospital were determined. These were compared with the local normals, with those of the junior members of staff in the same laboratory but who had put in less than 5 years continuous service and with a control group. The means in all five determinations were much higher in the senior members of staff than the normal standards of the area, particularly the IgG, which was almost double the local normals. The levels for the junior staff were on the whole slightly higher than the control group. The increase in the levels of immunoglobulins with corresponding increases in C3-Activator and 3Cc suggest that immunological reactions, with the binding of complement in the alternate and classical pathways of activation are taking place in most of these senior workers. In the absence of any manifest illness in the senior staff, the findings may suggest a high degree of immunological protection.

Adult↗

PubMed1979

Studies on human filariasis in Malaysia: immunoglobulin and complement levels in persons infected with Brugia malayi and Wuchereria bancrofti.

Levels of immunoglobulins G, A, M and E as well as complement components C3c and C4 have been determined in populations in various endemic areas in Peninsular Malaysia and also in filariasis patients. High immunoglobulin levels were seen. In the microfilarial-negative group IgG was 2009 mg% while IgE was 3967 I.U./ml. In the filariasis group, Wuchereria bancrofti patients had significantly higher levels of IgG, IgM and IgE, namely, 3314 mg%, 804 mg% and 18400 I.U./ml respectively. The significance of these levels is discussed.

Adolescent↗

PubMed2005

Immunoperoxidase versus immunofluorescence in the assessment of human renal biopsies.

BACKGROUND: For half a century, immunofluorescence (IF) on frozen sections has been the gold standard for immunohistochemical evaluation of renal biopsy specimens. In routine diagnostic immunohistopathologic evaluation, traditional IF has been replaced to a large extent by immunoperoxidase (IP) methods applied to paraffin sections of formaldehyde-fixed tissue. This is caused in part by the practical disadvantages inherent in the IF method, eg, separate tissue specimen and handling, UV microscopy, fading and impermanence of the label-making archiving, and difficult later investigation. Our aim for the present study is to evaluate IP as an alternative to IF in the diagnostic assessment of renal biopsy specimens. METHODS: Proteolytic antigen retrieval, antibodies effective on deparaffinized sections, a sensitive detection system (Dako EnVision HRP; Dako, Copenhagen, Denmark), and a standardized and rigorously controlled procedure were applied to a series of renal biopsy specimens (n = 81) previously classified by means of light microscopy (LM) and IF. Staining for immunoglobulin G (IgG), IgA, IgM, C1q, and C3c were recorded as positive or negative for IF and IP in paired proportions, presuming that IF was the test standard. RESULTS: Concordant observations were 71% for all (282 of 398 observations), 82% for IgG (65 of 79 observations), and 89% for IgA (72 of 81 observations). The majority of discordant observations (74 of 116 observations) were positive by means of IP, with mesangial deposits of IgM and C1q that were not found by IF. Statistically, there was no significant difference in outcomes between IF and IP for IgG, IgA, and C3c ( P > 0.2). In addition, IP staining allowed simultaneous evaluation of tissue by LM and therefore correlation between tissue structure and immune deposits not readily attained by IF. CONCLUSION: In the present study, it is documented that for the detection of IgG, IgA, and C3c, IP applied to protease-digested deparaffinized sections of formaldehyde-fixed renal tissue is, with few exceptions, equal to IF on frozen sections. The EnVision HRP method used here is several times more effective in terms of primary antibody dilution than earlier existing IP methods, and because the avidin-biotin system is not involved, very little nonspecific background staining will occur. Discordant observations (116 of 398 observations; 29%) were in the majority (91 of 116 observations) due to positive IP findings of IgM and C1q, which deserve additional investigation.

Biopsy, Needle↗

PubMed1987

A solid-phase anti-C3 assay for detection of immune complexes in six distinguished forms.

A solid-phase anti-C3 assay detecting immune complexes associated with C3 fragments is described. Two monoclonal antibodies against C3 fragments are used; one recognizes an epitope expressed on C3b, C3c and C3i, the other recognizes an epitope expressed on C3dg and iC3b. Combining these monoclonal anti-C3s with antibodies against class-specific immunoglobulins in enzyme-linked immunosorbent assay (ELISA), immune complexes (ICs) are detected in six distinguished forms; C3b-IgG-IC, iC3b/C3dg-IgG-IC, C3b-IgA-IC, iC3b/C3dg-IgA-IC, C3b-IgM-IC and iC3b/C3dg-IgM-IC. About three-fourths of the plasma samples from patients with active SLE or IgA-nephritis were found positive in one or more types of ICs. IgA-type ICs were found very frequently in patients with autoimmune or renal diseases.

Antibodies, Monoclonal↗

PubMed2001

Growth of Plasmodium falciparum induces stage-dependent haemichrome formation, oxidative aggregation of band 3, membrane deposition of complement and antibodies, and phagocytosis of parasitized erythrocytes.

Plasmodium falciparum-parasitized erythrocytes (RBCs) are progressively transformed into non-self cells, phagocytosed by human monocytes. Haemichromes, aggregated band 3 (Bd3) and membrane-bound complement fragment C3c and IgG were assayed in serum-opsonized stage-separated parasitized RBCs. All parameters progressed from control to rings to trophozoites to schizonts: haemichromes, nil; 0.64 +/- 0.12; 5.6 +/- 1.91; 8.4 +/- 2.8 (nmol/ml membrane); Bd3, 1 +/- 0.1; 4.3 +/- 1.5; 23 +/- 5; 25 +/- 6 (percentage aggregated); C3c, 31 +/- 11; 223 +/- 86; 446 +/- 157; 620 +/- 120 (mOD405/min/ml membrane); IgG, 35 +/- 12; 65 +/- 23; 436 +/- 127; 590 +/- 196 (mOD405/min/ml membrane). All increments in rings versus controls and in trophozoites versus rings were highly significant. Parasite development in the presence of 100 micromol/l beta-mercaptoethanol largely reverted haemichrome formation, Bd3 aggregation, C3c and IgG deposition and phagocytosis. Membrane proteins extracted by detergent C12E8 were separated on Sepharose CL-6B. Haemichromes, C3c and IgG were present exclusively in the high-molecular-weight fractions together with approximately 30% of Bd3, indicating the oxidative formation of immunogenic Bd3 aggregates. Immunoblots of separated membrane proteins with anti-Bd3 antibodies confirmed Bd3 aggregates that, in part, did not enter the gel. Immunoprecipitated antibodies eluted from trophozoites reacted preferentially with aggregated Bd3. Changes in parasitized RBC membranes and induction of phagocytosis were similar to oxidatively damaged, senescent or thalassaemic RBC, indicating that parasite-induced oxidative modifications of Bd3 were per se sufficient to induce and enhance phagocytosis of malaria-parasitized RBC.

Animals↗

PubMed1998

Acute phase and opsonin response in cardiac surgery patients: influence of underlying cardiac disease.

Cardiopulmonary bypass (CPB) leads to an activation of plasma cascade systems, complement activation, and an acute phase response. To evaluate the influence of the underlying cardiac disease on the activation pattern of these systems, we compared inflammatory changes in coronary artery bypass grafting (CABG) patients with patients undergoing aortic valve replacement. We investigated changes of the acute phase proteins alpha 1-proteinase inhibitor and fibrinogen, the unspecific opsonin fibronectin, and the complement components C3c and C4 induced by extracorporeal circulation in 12 patients undergoing aortic valve replacement and in 12 patients undergoing CABG. Concentrations of C3c and C4 decreased in both groups after the onset of CPB and C4 concentration remained below post-induction levels up to 24 h after onset of CPB (p = 0.04). Fibronectin levels dropped immediately before the onset of CPB (p = 0.01), reaching the lowest values after 20 min of extracorporeal circulation. Fibrinogen and alpha 1-proteinase inhibitor levels after induction of anaesthesia were significantly higher in the CABG group and remained higher throughout the entire study period (p < 0.001). As an indicator of a postoperative acute phase response, concentrations of both proteins rose in the postoperative period above post-induction levels (p < 0.02).

Acute-Phase Reaction↗

PubMedDate not supplied

Biochemical indices may not accurately reflect changes in nutritional status after allogeneic bone marrow transplantation.

The validity of biochemical indices routinely used for nutritional assessment was evaluated in patients undergoing allogeneic bone marrow transplantation for hematologic malignancies. Sixteen patients received total parenteral nutrition (TPN) for 15 days (35 kcal kg.body wt-1.day-1; 1.4 g amino acid.kg body wt-1.day-1) starting 1 day after transplantation. Nutritional status was evaluated before and after the TPN period by determining anthropometric (body weight, triceps skinfold thickness, and midarm circumference) and biochemical (transferrin, prealbumin, ceruloplasmin, and C3c) indices. Anthropometric indices, which were within the normal range before TPN, were not changed on day 15; transferrin and prealbumin concentrations significantly (p = 0.03) decreased whereas ceruloplasmin and C3c significantly (p = 0.03) increased. The levels of acute-phase proteins (alpha-1-acid glycoprotein, alpha-1-antitrypsin, and C-reactive protein), determined in 8 of the 16 patients at the same time intervals, were increased after 15 days of TPN and were significantly inversely correlated with transferrin and prealbumin. On the basis of these data, it appears that biochemical indices are not sufficiently reliable in the nutritional assessment of bone marrow transplantation patients because the levels of these substances are markedly affected by the acute-phase response secondary to febrile episodes and graft-versus-host disease, which frequently complicate transplantation.

Acute-Phase Proteins↗

PubMedDate not supplied

Alzheimer's disease and senile brains: an immunofluorescence study.

The results obtained with direct immunofluorescence techniques on normal, senile and Alzheimer's disease brains are reported. The antisera used were directed against C3c, IgG (gamma chain), IgG Fc., kappa and lambda light chains and anti-Ig (total). The brain samples were prepared in different ways: formalin-fixed and paraffin embedded; fresh frozen samples and alcohol fixed, paraffin-embedded samples. The images obtained with the different processing methods did not coincide. In order to obtain a more complete picture, we suggest the use of different methods on the same samples. In Alzheimer's disease brains, abundant but probably not monoclonal Ig antigenic determinants were found. Ig were found diffusely in the tissue, connected to amyloid (both in senile plaques and blood vessel walls), in glial cells and neurons. The significance of such data in relation to the genesis of brain amyloid are discussed.

Adult↗

PubMed2001

Detection of immune deposits in skin lesions of patients with Wegener's granulomatosis.

BACKGROUND: Wegener's granulomatosis (WG) is considered a pauci-immune systemic vasculitis based on the absence of immune deposits in renal biopsies of patients with active disease. In animal models of antineutrophil cytoplasmic antibody (ANCA) associated glomerulonephritis, immune deposits along the glomerular capillary wall are present at early stages of lesion development. These deposits are degraded rapidly, resulting in "pauci-immune" lesions. OBJECTIVE: To test the hypothesis that immune deposits can also be detected in early lesions of patients with WG, thereby initiating an inflammatory reaction that, in time, is augmented in the presence of ANCA, resulting in pauci-immune lesions later on. METHODS: The presence of immune deposits in skin biopsies taken within 48 hours of lesion development was investigated. Direct immunofluorescence was used to examine 32 skin biopsies for the presence of immune deposits (IgG, IgA, IgM, C3c). When possible, a comparison was made between the immunofluorescence findings in renal and skin biopsies taken at the same time. RESULTS: Four of 11 biopsies taken at initial presentation and four of 21 biopsies taken at the onset of a relapse of WG showed IgG and/or IgA containing immune deposits in the subepidermal blood vessels. All nine renal biopsies showed pauci-immune glomerulonephritis, irrespective of the presence (n=5) or absence (n=4) of immune deposits in the skin biopsy. CONCLUSION: A substantial number of skin biopsies showed immune deposits during active disease. These results could support the hypothesis that immune complexes may trigger vasculitic lesions in WG.

Adult↗

PubMed1978

[The influence of intraoperative autotransfusion (IAT) on plasmaproteins in patients with posttraumatic intraabdominal bleeding or hemorrhage during vascular surgery (author's transl)].

In 29 patients (12 vascular and 17 trauma cases) the effect of intraabdominal bleeding and surgical management under intraoperative autotransfusion on several plasmaproteins was examined. The following parameters were monitored immediately before and after autotransfusion as well as 24, 48, 72 hours and one week later, in the thawed serum: 1. albumen and the carrier proteins prealbumen, transferrin, retinol-binding protein, 2. acute phase reactants: c-reactive protein coeruloplasmin, haptoglobin, 3. fractions of complement: C1q, C3c, C5 and C 3-activator, 4. serum-cholinesterase. With usual treatment by infusion of electrolyte solutions during operation and the following days, and further applicated blood transfusion, plasma and fresh frozen plasma by clinical needs, while the immediate blood loss during operation was replaced by autotransfusion, there was no change in preoperative dates. Only at the 3rd day the typical picture of catabolic situation of the postoperative period was observed in vascular cases and not at all in trauma cases. Thus the changes were closely related to the preexisting disease or state of shock, without further detoriation by intraoperative autotransfusion. 7 days later a sometimes overshooting normalization of the parameters was observed. Only cholinesterase remained extremely low, especially in vascular cases.

Abdominal Injuries↗

PubMed1997

Complement activates neutrophils during PTCA procedure in patients with unstable angina pectoris.

We estimated adherence, aggregation and chemiluminescence of neutrophils as well as concentrations of C3c, C4 and C5 complement components and complement haemolytic activity (CH50) in 27 patients with unstable angina pectoris subjected to percutaneous transluminal coronary angioplasty (PTCA). The control group consisted of 12 patients with unstable angina pectoris, in whom coronary angiography was performed but PTCA was decided against for various reasons. Blood samples for examination were taken from coronary sinus and peripheral vein just before, 1 min and 20 min after PTCA or coronary angiography. We observed enhancement of neutrophil adherence, aggregation and chemiluminescence, and decrease in concentrations of C3c, C5 and complement haemolytic activity (CH50) after PTCA procedure. In conclusion we think that ischemia resulting from PTCA causes complement activation in an alternative pathway which seems to be connected with neutrophil activation.

Acute-Phase Reaction↗

PubMed1997

HIV is trapped and masked in the cytoplasm of lymph node follicular dendritic cells.

To gain further insight into the pathogenesis of human immunodeficiency virus (HIV) infection, lymph nodes from seven asymptomatic HIV+ subjects were analyzed during the latent phase of disease. Both ultrastructural and immunohistochemical analyses revealed that, in all of the cases, plasma cells producing IgM/gamma were present in germinal centers. Secreted immunoglobulins formed extracellular deposits mimicking the follicular dendritic cell network. Immunoglobulin produced by germinal center plasma cells are specific for HIV because they bind the HIV env protein gp 120. Plasma cells producing antibodies with the same specificity were also abundant in the extrafollicular regions of lymph nodes. During the latent phase of infection, the virus largely accumulates within the germinal centers. Therefore, extracellular immunoglobulin may form immune complexes, as shown by the presence of HIV-specific antibodies, HIV particles, and complement components C3c, C3d, and C1q in the interdendritic spaces. When the ultrastructural localization of HIV in germinal centers was analyzed, abundant virus particles were found in the interdendritic spaces. In addition to this extracellular localization of HIV, receptor-mediated endocytosis of viral particles by follicular dendritic cells was observed. Complete HIV particles were found within the endosomal compartment of the follicular dendritic cells and, as complete viral particles, free in the cytoplasm, indicating that the virus may escape from the endocytic compartment. As the virus is abundant in the cytoplasm, this event leads to formation of a hidden reservoir within follicular dendritic cells. In this location, HIV escapes recognition by cytotoxic T lymphocytes. In contrast, virus budding indicating a productive infection of follicular dendritic cells that would render them susceptible to T-cell-mediated lysis has been seldom observed.

Antigen-Antibody Complex↗