Regulation of immunoglobulin secretion by factor H of human complement

Immunology. 1985 Jul;55(3):419-26.

Abstract

As human B lymphocytes and macrophages carry surface receptors for Factor H (B1H), we investigated the possibility that this complement component regulates their function. Factor H inhibits immunoglobulin secretion by peripheral mononuclear cells (MNC) stimulated with pokeweed mitogen if present at the initiation of the cultures and at concentrations greater than 50 micrograms/ml. Factor H also inhibited stimulation and differentiation of purified B cells into immunoglobulin-secreting cells by Epstein-Barr virus (EBV). The inhibitory effect of Factor H was abrogated if anti-Factor H antibody was present in the cultures. EBV-transformed B-cell lines secreted less immunoglobulin if Factor H was present in the culture for at least 4 days. Culture of MNC with Factor H did not lead to the generation of suppressor T cells or macrophages. In contrast, Factor H did not cause proliferation of human peripheral total MNC or enriched T-cell or B-cell subpopulations. Also, Factor H did not inhibit the proliferation of MNC in response to several mitogens and antigens. Our results strongly indicate that Factor H is able to block human B-cell differentiation in vitro without blocking the proliferative ability of the cells. Factor H seems to act directly on the B cells through its receptor on their surface, since it inhibited T-dependent and T-independent B-cell differentiation but generated no suppressor cells.

MeSH terms

  • Antibody-Producing Cells / immunology
  • B-Lymphocytes / immunology*
  • Cell Transformation, Viral
  • Complement C3b Inactivator Proteins / immunology*
  • Complement Factor H
  • Hemolytic Plaque Technique
  • Herpesvirus 4, Human
  • Humans
  • Immune Tolerance
  • Immunoglobulins / biosynthesis*
  • Lymphocyte Activation*
  • Pokeweed Mitogens / pharmacology
  • T-Lymphocytes, Regulatory / immunology

Substances

  • Complement C3b Inactivator Proteins
  • Immunoglobulins
  • Pokeweed Mitogens
  • complement factor H, human
  • Complement Factor H