The Complement Group has a long history in studying the involvement of complement system, and especially its regulators in the context of disease and tissue injury.

We have a long-standing tradition and commitment to education. A total of 28 students have graduated and defended their PhD over the years with our group as the primary affiliation and 1-2 M.Sc students complete their master’s thesis yearly in the lab.

Seppo Meri

Professor of Immunology, Chief Physician

Professor Seppo Meri is Professor of Immunology at the Medical Faculty, University of Helsinki, Finland and the Chief Physician of Research in Microbiology at HUSLAB, laboratory of the Helsinki University Hospital. He is also a visiting professor at the Humanitas University, Milan, Italy. His medical speciality is in Clinical Microbiology. He served as a postdoctoral fellow at the University of Texas in 1988 and in 1989–90 as an EMBO fellow at MRC, Cambridge, UK. Seppo's research interests include diseases related to disturbances in complement regulation, pregnancy disorders, vascular damage and reasons for increased susceptibility to microbial infections. His group has published around 250 original research articles and 130 reviews or textbook chapters on complement, autoimmunity and microbial escape.

Seppo Meri's ResearchGate Profile
Seppo Meri's University of Helsinki TUHAT Profile

Hanna Jarva

MD, PhD, Docent of Immunology, Clinical Teacher

Hanna Jarva is Adjunct Professor and Senior Lecturer. She completed her PhD thesis with title: Interactions of Soluble Complement regulators with Pathogenic Bacteria, in 2004. She is a collaborator and currently she is working on projects involving complement and microbes and complement and autoimmunity.

Hanna Jarva's University of Helsinki TUHAT Profile

Tobias Freitag


Tobias Freitag is a medical researcher and an experimental immunologist, trained in gastroenterology and rheumatology. His scientific research is focused on (mucosal) immunology and translational medicine, autoimmune diseases - particularly, the celiac disease, mechanisms of tolerance to intestinal antigens (food, microbial and self-proteins), regulatory T cell function, and rodent disease models. He has been a principal investigator of the Finnish-Swedish NARPANord consortium, investigating the pathogenesis of type 1 narcolepsy, and is currently a member of the Academy of Finland Personalized Health-DIGIN Health research consortium, researching the microbial triggers of celiac disease. Since 2019, he has contributed as a Junior Researcher to the Translational Immunology Research Program at the University of Helsinki, studying therapeutic immune tolerance induction.

Tobias Freitag's University of Helsinki TUHAT profile

Ayman Khattab

PhD, Docent, Principal Investigator 

Ayman Khattab is a University researcher with over 15 years of experience in malaria research. Ayman obtained his PhD in 2003 from the University of Tübingen, Germany. He conducted his PhD work at the Institute for Tropical Medicine, University of Tübingen and the Albert Schweitzer Hospital, Lambaréné, Gabon where he studied the pathogenesis of placental malaria. In late-2003, Ayman started his post-doctoral work at Bernhard Nocht Institute for Tropical Medicine in Hamburg. He continued his research on placental malaria and PfEMP-1. He also expanded his research to cover other parasite surface antigens such as RIFINs and STEVORs, their expression in various stages of the parasites, their function and role in pathogenesis, and in the acquired immunity in individuals from malaria-endemic areas.

In July 2007, Ayman joined the Haartman Institute, University of Helsinki, to set up a malaria research lab. The lab maintains the malaria parasite, P. falciparum cultures and Anopheles mosquito colonies to study malaria pathogenesis and to develop novel interventions for the control of malaria transmission.

Specifically, Ayman focusses his research on 1) The surface antigens of P. falciparum as virulence factors 2) Complement escape by the P. falciparum parasite 3) The immune interaction between mosquitoes and the human host and 4) Mosquito control.

Ayman Khattab's University of Helsinki TUHAT profile

Marcel Messing

PhD, Senior Research Assistant

Marcel received his PhD in 1992 at the University of Maastricht, the Netherlands. The title of his thesis was Antihypertensive Drugs and the Microcirculation. He is a research assistant in the Complement group, assisting a number of researchers with their projects.

Marcel Messing's University of Helsinki TUHAT profile

Inkeri Lokki


Inkeri is a reproductive immunologist who defended her thesis on the immunogenetics of pre-eclampsia in 2017 at the University of Helsinki. Her research interests include genetic and immunological mechanisms in complications of human pregnancy. Inkeri also studies histology and immunology of the placenta. Her current projects aim at understanding the role of dysregulation of the complement system and immunogenetic incompatibility in early pregnancy in the etiology of pre-eclampsia and the range of complement-mediated mechanisms in the development of the disease in later pregnancy. 

Inkeri enjoys teaching and collaborates with several domestic and international research groups in reproductive epidemiology, complement studies in pregnancy, and vascular diseases.

Inkeri Lokki's ResearchGate 
Inkeri Lokki's University of Helsinki TUHAT profile

Eva Krzyzewska-Dudek


Eva holds a PhD in biological sciences from the Hirszfeld Institute of Immunology and Experimental Therapy in Wroclaw, Poland, where she investigated the role of the O-specific region length of lipopolysaccharide in complement evasion mechanisms of Salmonella bacteria. Since 2021, Eva studies T cell mediated immunity directed at SARS-CoV-2 in a consortium project with the Finnish National Public Health Institute, funded by the Academy of Finland. In addition, she investigates mechanisms of immune tolerance induction in collaboration with industry (celiac disease) and academic partners (narcolepsy type 1; Steve Miller's research group, Northwestern University, Chicago, USA). 

Subam Kathet

MSc, PhD student

Subam is a doctoral researcher currently pursuing his doctoral studies in affiliation with the doctoral program in Population Health at the Faculty of Medicine, University of Helsinki. He graduated with MSc degree in molecular medicine in 2016. During his MSc project at the Max Planck Institute for Infection Biology in Berlin, he investigated the phagocytic proteins in malaria vector Anopheles as a potential marker to characterize the mosquito hemocyte.

In 2018 Subam completed his MA degree in Anthropology, specializing in Medical Anthropology. During his MA thesis, he conducted an ethnographic study on community perception of malaria-associated fevers and health-seeking behavior within the community in rural Tanzania.

Subam has been associated with malaria research for over 4 years and has experience in malaria immunobiology, vector immunology, applied entomology and malaria epidemiology. As a part of his PhD project, Subam has been conducting epidemiological studies, community surveys and supervising the phase II semi-field trials and phase III community trials to evaluate the efficacy novel malaria control tools in reducing malaria transmission in the endemic region of Tanzania.

Vinaya Dulipati

MSc, PhD student 

Vinaya Dulipati graduated in 2018 with an MSc degree (5-year integrated programme) in biotechnology from the Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University (formerly University of Pune), India.

During her Master’s thesis work with us, she assessed several previously untested variants of the Lyme’s disease biomarkers to develop an effective proof of concept method for the screening of novel bacterial antigenic variants in patient cohorts.

She aims to explore further the complement evading mechanisms of opportunistic bacteria such as Pseudomonas, Acinetobacter, Klebsiella, and Enterobacter.

Sivan Glazer-Livson

MD,PhD student

Kadri Hendrikson

MD, PhD student

Leo Starck

MD, PhD student

Leo graduated as a MD from the University of Helsinki in 2015. While working as a junior doctor, he grew aware of the problems caused by antimicrobial resistance among pathogenic bacteria. This concern transformed into an interest in studying the field and assessing potential new remedies. In the current early phase of the PhD project, Leo is setting up assays for evaluating bacterial killing of several Gram-negative multi-drug resistant opportunistic pathogens by hyperimmune globulin, to be followed by potential clinical trials.

Lilli Leimi

MD, PhD student

Carmen Chen

PhD Student

Carmen Chen graduated in 2021 at the Norwegian University of Science and Technology (NTNU) with a MSc in Biotechnology. During her master’s thesis project, she identified a pivotal virulence factor which was exploited by a clinical isolated uropathogenic E. coli to induce inflammatory cell death in human macrophages.

After her graduation, she pursued her education as an early-stage researcher in the CORVOS project of The Marie Skłodowska-Curie Actions – Innovative Training Networks, which is a European joint doctoral program. Her project mainly focuses on bacterial adaptation mechanisms to different environments, and the interaction between multidrug-resistant, gram-negative bacteria, bacteriophages and the complement system. In addition to conducting her research at the University of Helsinki, she also did part of her research project at the Humanitas University in Milan.

Julia Roquigny

PhD Student

Julia graduated in 2018 at the University of Montpellier (France) with a master’s degree in biology and health, specializing in drug sciences. She conducted her MA thesis at the University of Glasgow (Scotland) on the use of metabolomics to understand the mechanisms of actions of anti-trypanosomal drugs. After graduation, she worked for 1 year and a half in a Belgian pharmaceutical industry as a research associate in investigative toxicology. She was involved in the management of in-vitro pharmacological profiling studies on novel molecules for the ongoing research projects, and in the research of adverse effects associated to pharmacological targets.

In 2020, She finally had the opportunity to join the European joint doctoral program 'CORVOS' of The Marie Skłodowska-Curie Actions – Innovative Training Networks, as an early-stage researcher.  Her PhD is undertaken at Sorbonne University (France) and the University of Helsinki. She is working on the role of acquired abnormalities in complement-associated rare kidney diseases.

In her spare time, she likes travelling, playing piano, knitting, hiking.

Mikel Rezola Artero

Mikel is an Early Stage Researcher from the Marie-Curie Sklodowska Innovative Training Network “CORVOS”.  “CORVOS” is a European Joint Doctorate with involvement from academic and industrial partners focused on the role of the complement system in opportunistic infections. His PhD will be undertaken at the University of Helsinki (Finland) and the Sorbonne University (France). The project is focused on the study of complement evasion molecules in Plasmodium parasites and anopheline mosquitoes as potential vaccine antigens.

In 2020, he graduated from the MSc Leading International Vaccinology Education (“LIVE”). This Erasmus+ Mundus Joint Master’s Degree is composed of 5 different main universities (in Spain, Belgium and France) and more than 40 international associated partners (including GSK Vaccines and Sanofi Pasteur). The topic of his master’s thesis was non-neutralising antibody responses against CMV, he investigated ADCP and ADCC responses specific to CMV glycoproteins during pregnancy and their possible correlation with the risk of congenital infection.

Mikel’s interests are biotechnology, immunology research and vaccines. Outside the lab, he likes hiking, travelling, reading and cooking.

Hang Zhong

Hang is a student of the joint PhD program CORVOS, under Humanitas University in Milano, and the University of Helsinki. She studies science in multiple disciplines, from physics, mathematics to life sciences. In her spare time, she enjoys studying subjects such as international relations, economics and social development. 

Varuni Ratnayake


Varuni Ratnayake, from Sri Lanka, is working as a technical / research assistant in the Malaria project which is supervised by Ayman Khattab. Her job related tasks are exploring immune evasion strategies of Malaria parasites and anaerobic bacterial species in the complement cascade. She has successfully completed two M.Sc. programmes in terms of M.Sc. in Cellular and Molecular Immunology from Institute of Biochemistry, Molecular Biology and Biotechnology (IBMBB), University of Colombo (2016-2018) and M.Sc. in Biochemistry from Faculty of Biochemistry, Molecular Medicine (FBMM), University Oulu (2020-2022). Furthermore, she has worked as a Teaching / Scientific assistant for the cellular and molecular immunology Masters students at the IBMBB for two years (2018-2020).

Mari Humalajoki

MSc student

Mari graduated a Bachelor of Science in Molecular Biosciences from Helsinki University in 2020, and a Master in Medical Sciences with a main focus in Forensic Science from Uppsala University in 2022. Now she is completing her master's degree in Genetics and Molecular Biosciences; Molecular and Analytical Health Biosciences at the Meri Complement group studying a patient case in genetically inherited total C3-deficiency. She is hoping to continue to her education towards a PhD in immunogenetics and pathology. During her spare time, she is the chair of a student theatre group, as well as enjoys acting, singing, classical piano and crafts.

Marjo Rissanen

Medical Laboratory Technologist

Liisa Penttilä


Liisa takes care of the administrative issues related to group projects. She takes care of HR matters, communication and meeting arrangements. She coordinates grant applications and reports, follows budgets etc.

M.Sc Students
  • Uni Rankka 2020 -
  • Vinaya Dulipati 2018 - 2019
  • Viivi Koivu 2017 - 2018
  • Stella Polido 2017 - 2018
Complement Group Alumni
  • Martin Reichardt, PhD
  • Antti Lavikainen, MD, VetD, PHD
  • Anna-Helena Saariaho, PhD
  • Eva Krzyżewska, MSc
  • Laura Teirilä, PhD
  • Anni Kleino, PhD
  • Juha Kotimaa, PhD