C1q: Its functions within the innate and adaptive immune responses and its role in lupus autoimmunity

Richard D. Sontheimer, Emil Racila, Doina M. Racila

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77 Scopus citations


The complement cascade is a multi-faced effector component of the innate immune response. C1q is the recognition component of the classical pathway of complement activation. In addition, C1q has been recognized to serve a number of other biological functions including a modulating role on cellular functions within the adaptive immune response. The importance of C1q to normal immune regulation is reflected by the fact that greater than 90% of individuals who have complete congenital deficiency of C1q have been observed to develop early-onset photosensitive systemic lupus erythematosus (SLE). As a number of single nucleotide polymorphisms have been identified in three C1q genes, it is possible that more subtle variations in C1q expression could be a risk factor for cutaneous LE and SLE. Thus, a more comprehensive delineation of complotype could be of increasing clinical importance in the future.

Original languageEnglish (US)
Pages (from-to)14-23
Number of pages10
JournalJournal of Investigative Dermatology
Issue number1
StatePublished - Jul 2005

Bibliographical note

Funding Information:
The preparation of this manuscript was supported by the National Institutes of Health (NIAMS) grant AR19101. But its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIAMS. In addition, the preparation of this manuscript was also supported by a consortium of University of Iowa Department of Dermatology endowment funding (The Herzog Foundation, The Joseph Marshall Family of Morningside, Iowa, and the John S. Strauss Endowed Chair in Dermatology). The authors would like to thank Dr Marina Botto for reviewing the manuscript and for her thoughtful input concerning the fine balance that exists between the physiological and pathological roles of complement activation.


  • C1q
  • Innate immune response
  • Subacute cutaneous lupus erythematosus (SCLE)
  • Systemic lupus erythematosus (SLE)


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