Glucocorticoid-free remission in patients with SLE in the era of biologics: Immune complex disease is likely to benefit from current medications.

OBJECTIVES: In addition to various immunosuppressive agents, belimumab and anifrolumab became available in Japan. We aimed to investigate glucocorticoid-free clinical remission in a single-centre retrospective cohort in October 2023. METHODS: Our cohort included patients with SLE who needed to start or increase glucocorticoids for disease activity and were followed up for more than 1 year. We investigated the rate of achievement of clinical remission off corticosteroids (CR off C), defined as no clinical score on the SLEDAI-2K without glucocorticoids, baseline predictors of CR off C, medications used when CR off C was achieved, and flare rates following CR off C. RESULTS: Out of the 60 patients followed for an average of 5.4 (±2.6) years, 17 (28.3%) achieved CR off C in 3.6 (±1.2) years after enrolment. Use of belimumab and anifrolumab accounted for eight (47.1%) of the achievers. Among the baseline data, male sex, recent enrolment, high glucocorticoid dose, and detection of immune complex (IC) significantly predicted CR off C, while lupus nephritis (LN) and a low C3 level tended to predict it. In the multivariate analysis, IC detection was the only predictor of CR off C. Clinical flares were observed in 5.9% of the achievers during a median 1.2 years after achievement of CR off C. CONCLUSION: In the era of biologics, CR off C was achieved in 28.3% of the patient cohort requiring the start or increase of glucocorticoids for disease activity, with a relatively low rate of flares, suggesting that glucocorticoid-free clinical remission is an achievable target in SLE. IC disease, represented by male sex or nephritis, is likely to benefit from currently available medications.

Identification of key genes and imbalance of immune cell infiltration in immunoglobulin A associated vasculitis nephritis by integrated bioinformatic analysis.

Background: IgAV, the most common systemic vasculitis in childhood, is an immunoglobulin A-associated immune complex-mediated disease and its underlying molecular mechanisms are not fully understood. This study attempted to identify differentially expressed genes (DEGs) and find dysregulated immune cell types in IgAV to find the underlying pathogenesis for IgAVN. Methods: GSE102114 datasets were obtained from the Gene Expression Omnibus (GEO) database to identify DEGs. Then, the protein-protein interaction (PPI) network of the DEGs was constructed using the STRING database. And key hub genes were identified by cytoHubba plug-in, performed functional enrichment analyses and followed by verification using PCR based on patient samples. Finally, the abundance of 24 immune cells were detected by Immune Cell Abundance Identifier (ImmuCellAI) to estimate the proportions and dysregulation of immune cell types within IgAVN. Result: A total of 4200 DEGs were screened in IgAVN patients compared to Health Donor, including 2004 upregulated and 2196 downregulated genes. Of the top 10 hub genes from PPI network, STAT1, TLR4, PTEN, UBB, HSPA8, ATP5B, UBA52, and CDC42 were verified significantly upregulated in more patients. Enrichment analyses indicated that hub genes were primarily enriched in Toll-like receptor (TLR) signaling pathway, nucleotide oligomerization domain (NOD)-like receptor signaling pathway, and Th17 signaling pathways. Moreover, we found a diversity of immune cells in IgAVN, consisting mainly of T cells. Finally, this study suggests that the overdifferentiation of Th2 cells, Th17 cells and Tfh cells may be involved in the occurrence and development of IgAVN. Conclusion: We screened out the key genes, pathways and maladjusted immune cells and associated with the pathogenesis of IgAVN. The unique characteristics of IgAV-infiltrating immune cell subsets were confirmed, providing new insights for future molecular targeted therapy and a direction for immunological research on IgAVN.

Injection Site Reaction to Various Insulins as Type III Allergy With Urticarial Vasculitis in a Patient With Type I Diabetes Mellitus.

ABSTRACT: Injection site reactions are defined as skin reactions at the injection site to drugs administered subcutaneously. Pathophysiologically, these reactions are based on different immunological mechanisms. We report the case of a 49-year-old patient with type 1 diabetes mellitus (first diagnosis in 1994 at the age of 23 years). Continuous subcutaneous insulin infusion using an insulin pump has been used for many years. The patient presented to the department of dermatology with progressive symptoms in the area of the insulin injection sites on the lower abdomen, accompanied by pain, burning, erythema, tenderness, and the formation of subcutaneous nodules. Previous attempts to use different insulins and to change the injection sites did not improve his symptoms. Furthermore, the symptoms appeared within hours after the insulin pump was attached, so that the injection site has to be changed as soon as every 48 hours. No anaphylactic shock was reported at any time. Multiple histological specimens were obtained from an older lesion on the abdomen as well as from test sites after standard allergological tests (prick and intradermal tests) of various insulins. Histologically, these biopsies showed the image of an extensive deep-reaching small vessel vasculitis with the aspect of an urticarial vasculitis and confirmed the diagnosis of an injection-site reaction that can be characterized as a type III hypersensitivity reaction.

Triple-threat quantitative multiplexed plasma proteomics analysis on immune complex disease MRL-lpr mice.

Systemic lupus erythematosus is a common autoimmune inflammatory disease which is associated with increases in autoantibodies and immune complexes that deposit in the kidney. The MRL-lpr mouse is a common mouse model used for the study of lupus and immune complex glomerulonephritis but very little is known about the plasma proteome changes in this model. We performed in-depth quantitative proteome profiling on MRL-lpr and control (strain MpJ) mice to investigate the changes in the proteome, immunoglobulins and their glycoproteome as well as protein and immune complexes. Methodologies used included immunohistochemistry, immunoglobulin isotyping, multiplexed proteome profiling, immunoglobulin immunoprecipitation with glycoproteome profiling, and size exclusion chromatography (SEC) profiling to enable a comprehensive proteome profiling of proteins and protein complexes. We also used a novel native multiplexed plasma proteome profiling (NativeMP3) method that relies on native enrichment of plasma proteins enabling ultra-deep single shot profiling where we identified 922 plasma proteins at 1% false discovery rate (FDR) in a single shot mass spectrometry run. We observed many large plasma protein differences between the MRL-lpr and control strain including differences in the immunoglobulins, immunoglobulins against specific antigens, chemokines, and proteases as well as changes in protein complexes such as the immunoproteasome.

Therapeutic plasma exchange for the management of a type III hypersensitivity reaction and suspected immune-mediated vasculitis assumed to be caused by human albumin administration in a dog.

OBJECTIVE: To describe the successful treatment of a life-threatening type III hypersensitivity reaction suspected to have been related to human serum albumin (HSA) administration in a dog with therapeutic plasma exchange (TPE). CASE SUMMARY: A 3-year-old neutered male mixed breed dog was suspected to have developed immune-mediated vasculitis 2 weeks after the administration of HSA (740 mg/kg) for the management of hypoalbuminemia resulting from septic peritonitis. The dog was presented with fever, edema, hypoalbuminemia (26 g/L [2.6 g/dL]; reference interval, 30-44 g/L [3.0-4.4 g/dL]), and coagulopathy. The dog was treated with fresh frozen plasma (FFP) and glucocorticoids but remained hypoalbuminemic (18 g/L [1.8 g/dL]) and developed acute kidney injury (AKI). Over 4 days, 3 TPE treatments were performed, with a total of 2.7 plasma volumes exchanged. Replacement fluids consisted of a combination of FFP, hydroxyethyl starch 6%, and 0.9% saline solution. Following TPE treatments, serum albumin concentration increased (from 18 g/L [1.8 g/dL] to 25 g/L [2.5 g/dL]), serum creatinine concentration decreased (from 340 µmol/L [3.9 mg/dL] to 87 µmol/L [0.98 mg/dL]), and clotting times normalized (activated partial thromboplastin time decreased from 33 seconds to 14.5 seconds). There was a gradual but consistent clinical improvement of the edema and overall demeanor of the dog. No significant adverse effects were noted during the TPE treatments, and the dog was discharged after 8 days of hospitalization. Following discharge, the dog had complete clinical resolution of edema and AKI. NEW/UNIQUE INFORMATION: This is the first report describing successful use of TPE for the management of an immune-mediated reaction (type III hypersensitivity) following HSA administration.

Macrophage Depletion Reduces Disease Pathology in Factor H-Dependent Immune Complex-Mediated Glomerulonephritis.

Complement factor H (FH) is a key regulator of the alternative pathway of complement, in man and mouse. Earlier, our studies revealed that the absence of FH causes the C57BL6 mouse to become susceptible to chronic serum sickness (CSS) along with an increase in the renal infiltration of macrophages compared to controls. To understand if the increased recruitment of macrophages (Mϕs) to the kidney was driving inflammation and propagating injury, we examined the effect of Mϕ depletion with clodronate in FH knockout mice with CSS. Eight-week-old FHKO mice were treated with apoferritin (4 mg/mouse) for 5 wks and with either vehicle (PBS) or clodronate (50 mg/kg ip, 3 times/wk for the last 3 weeks). The administration of clodronate decreased monocytes and Mϕs in the kidneys by >80%. Kidney function assessed by BUN and albumin remained closer to normal on depletion of Mϕs. Clodronate treatment prevented the alteration in cytokines, TNFα and IL-6, and increase in gene expression of connective tissue growth factor (CTGF), TGFß-1, matrix metalloproteinase-9 (MMP9), fibronectin, laminin, and collagen in FHKO mice with CSS (P < 0.05). Clodronate treatment led to relative protection from immune complex- (IC-) mediated disease pathology during CSS as assessed by the significantly reduced glomerular pathology (GN) and extracellular matrix. Our results suggest that complement activation is one of the mechanism that regulates the macrophage landscape and thereby fibrosis. The exact mechanism remains to be deciphered. In brief, our data shows that Mϕs play a critical role in FH-dependent ICGN and Mϕ depletion reduces disease progression.

Case series of idiopathic intracranial hypertension in three patients with immune-complex glomerulonephritis.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is defined by an increased cerebrospinal fluid pressure in the absence of inflammation, structural obstructions, or mass lesions. Although the underlying pathogenesis of IIH is not fully understood, associations with specific risk factors as obesity, obstruction of cerebral venous sinuses, medications, endocrine or systemic conditions and chronic kidney disease have been described. Immune-complex glomerulonephritis as IgA-nephropathy is a frequent cause of chronic kidney failure, which was reported previously in one IIH patient. To date, there is no knowledge about the variable relation of immune-complex nephritis, kidney function and the course of IIH. CASE PRESENTATION: We report three cases (two females) of concurrent diagnosis of IIH and immune-complex glomerulonephritis. All patients presented with typical IIH symptoms of headache and visual disturbances. Two patients had been diagnosed with IgA-nephropathy only few weeks prior to IIH diagnosis. The third patient had been diagnosed earlier with terminal kidney failure due to a cryoglobulin glomerulonephritis. CONCLUSION: We propose a possible link between renal deposition of immune-complexes and increased cerebrospinal fluid pressure. Pathophysiological hypotheses and clinical implications are discussed. We recommend clinical awareness and further systematic research to obtain more information on the association of IIH and immune-complex glomerulonephritis.

The Clinical Features of FLAIR-Hyperintense Lesions in Anti-MOG Antibody Associated Cerebral Cortical Encephalitis with Seizures: Case Reports and Literature Review.

Background: The presence of fluid attenuated inversion recovery (FLAIR)-hyperintense lesions in anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated cerebral cortical encephalitis with seizures (FLAMCES) was recently reported. However, the clinical characteristics and outcome of this rare clinico-radiographic syndrome remain unclear. Methods: The present study reported two new cases. In addition, cases in the literature were systematically reviewed to investigate the clinical symptoms, magnetic resonance imaging (MRI) abnormalities, treatments and prognosis for this rare clinico-radiographic syndrome. Results: A total of 21 cases were identified during a literature review, with a mean patient age at onset of 26.8 years. The primary clinicopathological characteristics included seizures (100%), headache (71.4%), fever (52.3%) and other cortical symptoms associated with the encephalitis location (61.9%). The common seizure types were focal to bilateral tonic-clonic seizures (28.6%) and unknown-onset tonic-clonic seizures (38.1%). The cortical abnormalities on MRI FLAIR imaging were commonly located in the frontal (58.8%), parietal (70.6%) and temporal (64.7%) lobes. In addition, pleocytosis in the cerebrospinal fluid was reported in the majority of the patients (95.2%). All patients received a treatment regimen of corticosteroids and 9 patients received anti-epileptic drugs. Clinical improvement was achieved in all patients; however, one-third of the patients reported relapse following recovery from cortical encephalitis. Conclusions: FLAMCES is a rare phenotype of MOG-associated disease. Thus, the wider recognition of this rare syndrome may enable timely diagnosis and the development of suitable treatment regimens.

Late Corneal Stromal Deposits After COVID-19.

ABSTRACT: We present 2 cases of striking stromal corneal infiltrates months after COVID-19 infection. While we cannot prove that these infiltrates are caused by or directly related to COVID-19, we did not find any other plausible cause that could explain these ophthalmic signs. In these cases, the ongoing process was detected in relatively early stages due to scheduled visits with patients and responded positively to prednisolone acetate 1% ophthalmic suspension. However, we do not know the response to treatment in more advanced cases.

An explanation of the pathogenesis of several autoimmune diseases in immuno-compromised individuals.

Some pathogen infections and immune system deficiencies have been linked to a few autoimmune diseases. However, the pathogenesis of most autoimmune diseases is unknown. An explanatory hypothesis for the pathogenesis of infection-initiated autoimmune diseases is provided. Virulent pathogen infections create extensive pathogen antigens that frequently require antibodies. These antibodies create extensive antigen-antibody immune complexes, which some immuno-compromised individuals will not adequately eliminate. This will cause inflammatory type III hypersensitivity symptoms, including protease releases that destroy epithelium, mesothelium and endothelium basement membranes, express new immunogenic antigens from previously sequestered basement membrane constituents, and ultimately induce new autoantibodies. This can continue after the infection ends, if the first wave of protease attacks on basement membranes induces new autoantibodies that cause new uncleared antigen-antibody immune complexes and type III hypersensitivity reactions. The secreted proteases and other enzymes will have preferred substrates and these proteases or other enzymes by themselves, or by their processed protein substrates, can express immunogenic antigens that induce new autoantibodies and initiate various autoimmune diseases. In summary, several autoimmune diseases can be initiated in immuno-compromised individuals during extensive pathogen infections, if these individuals have two immune problems: (a) slow or weak initial immune responses that result in a reliance on antibodies and (b) an inability to eliminate the resulting antigen-antibody immune complexes by phagocytosis. These two immune problems and the resulting immune system type III hypersensitivity reaction can explain the causation of several autoimmune diseases, including the most common and the rarest autoimmune diseases, both their differences and their similarities.

Fotobiomodulação na síndrome de stevens-johnson: relato de caso / Photobiomodulation for stevens-johnson syndrome: case report

Introdução: A Síndrome Stevens-Johnson (SSJ) é uma doença causada por hipersensibilidade a imunocomplexos e pode ser desencadeada por distintos fármacos, dentre eles a fenitoína. Devido sua complexidade e raridade, ainda nãohá consenso de tratamento padrão ouro, porém sabese da necessidade da atuação multidisciplinar. Para os cuidados com as feridas, pode-se citar os curativo se a fotobiomodulação (FBM). Objetivo: Relatar o uso da FBM como terapia complementar em um caso de SSJ no Hospital Universitário Regional dos Campos Gerais (HU-UEPG). Métodos: Paciente sexo feminino, 26 anos, deu entrada na unidade de terapia intensiva (UTI) com diagnóstico de SSJ secundária ao uso de fenitonína, escore de SCORTEN 1, com área sem epitélio íntegro 10- 30% e área acometida por lesões de 94,5%, poupando apenas o couro cabeludo. Foi abordada e tratada por uma equipe multidisciplinar e solicitado vaga em centro de especializado em queimados. No sétimo dia de UTI foi iniciado tratamento com FBM, 2 J por ponto, distância entre pontos de 2cm, comprimento onda vermelho (660nm), nas feridas que não apresentavam secreção, foram cinco sessões com intervalo de três dias entre a terceira e a quarta. Resultados: A paciente apresentou melhora visível das lesões cutâneas e recebeu alta hospitalar 5 dias após cessação da FBM. Conclusão: O uso da FBM pode ser efetiva no tratamento complementar da fase aguda SSJ desencadeada por fenitoína.

Introduction: Stevens-Johnson Syndrome (SJS) is a disease caused by hypersensitivity to immune complexes and can be triggered by different drugs, including phenytoin. Due to its complexity and rarity, there is still no consensus on gold standard treatment, but the need for multidisciplinary action is known. For wound care, dressings and photobiomodulation (PBM) can be mentioned. Objective: This study is to report the use of PBM as complementary therapy in a case of SJS at Hospital Universitário Regional dos Campos Gerais (HU-UEPG). Methods: A 26-year-old female patient was admitted to the intensive care unit (ICU) diagnosed with SJS secondary to the use of phenytoin, SCORTEN score 1, with an area without intact epithelium 10-30% and an area affected by injuries of 94.5 %, saving only the scalp. She was approached and treated by a multidisciplinary team which requested a place in a specialized burn center. On the seventh day of ICU, treatment with PBM, 2J per point was started, distance between points of 2cm, red wave length (660nm), in wounds that did not present secretion, with a total of five sessions with an interval of three days between the third and fourth. Results: The patient showed a visible improvement of skin lesions and was discharged from hospital 5 days after cessation of PBM. Conclusion: Use of PBM can be effective in complementary treatment of acute SJS phase triggered by phenytoin.

Catching the Worm Early: An Atypical Case of Bancroftian Filarial Nephropathy.

Filarial glomerular disease has been attributed to circulating immune complex deposition. We report here a rare manifestation of filarial nephropathy with microfilariae documented in glomerular capillaries in addition to immune complex glomerulonephritis, thus suggesting that direct toxicity may also contribute to the pathogenesis of this entity.

Asociación entre pancreatitis autoinmune y colitis ulcerosa: descripción de 12 pacientes / No disponible

INTRODUCCIÓN: las manifestaciones pancreáticas en enfermedad inflamatoria intestinal (EII) incluyen principalmente pancreatitis aguda secundaria a fármacos y, con menor frecuencia, pancreatitis autoinmune. Existe asimismo una asociación particular con la pancreatitis autoinmune tipo 2. MÉTODOS: estudio retrospectivo de pacientes con diagnóstico de colitis ulcerosa (CU) y pancreatitis autoinmune (PAI) en control en dos centros en Santiago de Chile, entre los años 2007 y 2018. Se registraron datos clínicos, resultados de laboratorio e imágenes, evolución en el tiempo y tratamientos utilizados. RESULTADOS: se identificaron 12 pacientes con ambas enfermedades, la edad promedio fue 34 años, con un 42 % de sexo masculino. En todos los casos se estableció el diagnóstico probable de PAI tipo 2 en base a la resonancia magnética (RM) de páncreas, la asociación con EII y la rápida respuesta a tratamiento con corticoides. En dos casos se tomaron muestras para estudio histológico pero el resultado fue no concluyente. Se observó recurrencia de la PAI en un solo caso. El 58 % de los pacientes tenían una CU extensa, el 100 % recibe tratamiento con 5-ASA y el 33 %, con azatioprina. Solo un paciente tuvo un brote grave y ninguno presentó complicaciones, necesidad de tratamiento con biológicos ni cirugía. CONCLUSIÓN: en nuestra casuística se confirma la asociación entre CU y PAI tipo 2. No se observó mayor severidad de la EII en este grupo de pacientes

No disponible

Delayed type III hypersensitivity reaction with acute kidney injury in two dogs following administration of concentrated human albumin during treatment for hypoalbuminemia secondary to septic peritonitis.

OBJECTIVE: To describe 2 dogs with acute kidney injury secondary to type III hypersensitivity reaction to 25% human serum albumin (HSA). CASE SERIES SUMMARY: Two dogs were presented with evidence of septic peritonitis. The dogs were hospitalized following definitive surgical correction of a jejunal laceration following routine ovariohysterectomy, and removal of a jejunal foreign body. In the postoperative period, both dogs developed hypoalbuminemia and received 25% HSA. At the time of initial discharge, both dogs were doing well clinically and had normal renal parameters. Eleven and 18 days after HSA infusion, respectively, both dogs were re-presented with clinical signs of inappetence, vomiting, and lameness that progressed to urticaria, peripheral and angioedema, and petechiae, consistent with a delayed type III hypersensitivity reaction. Treatment for the type III hypersensitivity reaction to HSA included administration of diphenhydramine and glucocorticoids. Despite partial resolution of edema and joint swelling, both dogs developed progressive azotemia together with hypoalbuminemia and proteinuria. One dog developed an anuric acute kidney injury (AKI). Both dogs were humanely euthanized. Histopathology of the kidneys of both dogs was consistent with immune complex deposition and vasculitis. NEW OR UNIQUE INFORMATION: Severe type III hypersensitivity reactions have been documented in healthy dogs and clinical patients following the administration of HSA. This report describes the first documented delayed type III hypersensitivity reaction in 2 dogs with septic peritonitis that resulted in AKI, glomerulonephritis, and oligo- to anuria in clinical patients following administration of 25% HSA.

A viral infection explanation for Kawasaki disease in general and for COVID-19 virus-related Kawasaki disease symptoms.

SARS-CoV-2, a new virus that appeared in Wuhan, China, in 2019 has approximately an 80% genomic match to the Severe Acute Respiratory Symptom (SARS) virus, which is known to come from a bat virus. Symptoms of Kawasaki disease in general and incomplete Kawasaki disease have been seen in a subset of pediatric patients having a current or previous infection of SARS-CoV-2. A viral infection, such as a SARS-CoV-2 virus infection, could result in extensive antigen-antibody immune complexes that cannot be quickly cleared in a subset of patients and thus create a type III hypersensitivity immune reaction and cause Kawasaki disease or Kawasaki disease symptoms (also known as multisystem inflammatory syndrome) in a subset of patients. Extensive binding of antibodies to viral antigens can create antigen-antibody immune complexes, which, if not eliminated in certain individuals having dysfunctional complement systems, can start inflammatory type III hypersensitivity symptoms, including protease releases that can disrupt epithelium, mesothelium, and endothelium basement membranes, and induce pervasive inflammation throughout the body. This could continue after SARS-CoV-2 infections end if the first wave of protease attacks on basement membranes created new secondary autoantibodies and new uncleared antigen-antibody immune complexes.

Resolution of IgA and C3 immune deposits in Staphylococcus infection-associated glomerulonephritis in a kidney transplant recipient
.

Staphylococcus infection-associated glomerulonephritis (SAGN) is characterized by the presence of IgA and C3 as the predominant components present in the glomerular immune deposits. Glomerulonephritis frequently resolves after effective treatment of the staphylococcal infection. However, there have been few studies of repeat kidney biopsy after resolution of glomerulonephritis. We present a combined kidney-pancreas transplant patient who developed SAGN due to Staphylococcus aureus bacteremia from an old infected arteriovenous (AV) graft, which occurred after a long period of stable allograft function. Clinical improvement occurred following surgical debridement and appropriate antibiotics with subsequent clearance of bacteremia. However, 3 weeks later he presented with severe acute kidney injury related to rapidly progressive glomerulonephritis. Renal allograft biopsy revealed immune complex glomerulonephritis with predominance of IgA and C3 in subendothelial and mesangial deposits, consistent with SAGN. There was no evidence for recurrent staphylococcal infection. High-dose steroid therapy was followed by resolution of hematuria and improvement in allograft function with gradual return of serum creatinine concentration to near baseline levels. However, 1 year after the diagnosis of SAGN, he developed gradually worsening allograft function with persistent proteinuria. Repeat allograft biopsy showed sclerosing glomerular changes and extensive interstitial fibrosis and tubular atrophy. There was complete resolution of proliferative changes, and IgA and C3 deposits were no longer detectable. Despite transient allograft function stabilization, the patient progressed to end-stage renal disease (ESRD), and maintenance hemodialysis was reinitiated 2.5 years after the diagnosis of SAGN. Pancreatic allograft function remained normal.

Type 3 hypersensitivity in COVID-19 vasculitis.

Coronavirus Disease 2019 (COVID-19) is an ongoing public health emergency and new knowledge about its immunopathogenic mechanisms is deemed necessary in the attempt to reduce the death burden, globally. For the first time in worldwide literature, we provide scientific evidence that in COVID-19 vasculitis a life-threatening escalation from type 2 T-helper immune response (humoral immunity) to type 3 hypersensitivity (immune complex disease) takes place. The subsequent deposition of immune complexes inside the vascular walls is supposed to induce a severe inflammatory state and a cytokine release syndrome, whose interleukin-6 is the key myokine, from the smooth muscle cells of blood vessels.

Recurrent macroscopic hematuria in a pediatric patient: is it early to diagnose as having type I hereditary C2 deficiency?

Hereditary C2 deficiency is the most common early complement deficiency and characterized by recurrent infections and autoimmunity despite most patients are also asymptomatic. Type I hereditary C2 deficiency is caused by a heterozygous deletion in C2 gene resulting in early stop codon and lack of C2 production. Clinical spectrum may vary and pure nephrological involvement without the presence of recurrent infections is scarce in hereditary C2 deficiency.We report here a previously healthy 14-year-old boy presenting recurrent self-limited macroscopic hematuria and persistently low serum C4 levels, diagnosed as having type I hereditary C2 deficiency with confirming a novel heterozygote deletion (c.1567 + 22_1567 + 43del) in C2 gene. He has been remained asymptomatic for the next 18 months. Since the diagnosis of C2 deficiency was made in the absence of organ-threatening involvement such as immune complex-mediated glomerulonephritis, we think that early diagnosis and optimal follow-up may improve life-span of the patients with hereditary early complement deficiencies.