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A Possible Initiating Role of B Cells
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From the * Noda Institute for Scientific Research, Noda-shi, Chiba-ken 278, Japan; Complement (C) is an important component of innate immunity, and was also shown recently
to participate in induction of acquired B cell humoral immunity. In this study, we present evidence that C also participates in acquired T cell immunity.
We found that C was involved in early events of the efferent elicitation phase of contact sensitivity (CS), and delayed-type hypersensitivity (DTH). Thus, CS and DTH were inhibited by
administration of a C-blocker, soluble recombinant C receptor-1 (sCR1), when given 30 min
before, but not 3 h after local antigen challenge. Among C components, local C5 were thought
crucial to elicitation of CS, since local administration of anti-C5 monoclonal antibodies or locally injected C-depleting cobra venom factor also inhibited CS and DTH. These findings
were consistent with our previous finding of the importance of C5 for CS elicitation, using
congenitally C5-deficient mice. To dissect the mechanism of C dependence in CS, we demonstrated that locally increased early macrophage chemotactic activity (probably C5a) in evolving
CS skin extracts, as well as late elaboration of IFN- In summary, these results suggest that C was activated locally, perhaps via a B cell product, in
an important early component of the stepwise events necessary to elicit CS, leading to local production of C5-dependent macrophage chemotactic activity and later IFN-
Section of
Pulmonary and Critical Care Medicine, Department of Internal Medicine, Yale University School of
Medicine, New Haven, Connecticut 06520-8013; § Alexion Pharmaceuticals Inc., New Haven,
Connecticut 06511;
Department of Veterinary Surgery, College of Agriculture, Osaka Prefecture
University, Sakai, Osaka 593, Japan; and the ¶ Section of Allergy and Clinical Immunology,
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
06520-0813
, were both inhibited by anti-C treatment. In addition, histological analysis showed that leukocyte recruitment into CS ear sites was similarly C-dependent. Furthermore, an initiating role of B cell-derived C-fixing immunoglobulin
was suggested by demonstration of impaired CS responses in B cell-deficient mice.
, and subsequently leading to cell infiltration, for development of T cell-dependent CS.
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