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Interleukin 1 can replace monocytes for the specific human B-cell response to a particulate antigen
Cellular Immunology
|July 1, 1984
Summary
Human B cell anti-trinitrophenyl (TNP) responses to TNP-polyacrylamide beads require monocytes. Monocyte supernatants, including interleukin-1 (IL-1), can restore B cell responses, but monocytes do not act as antigen-presenting cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- The anti-trinitrophenyl (TNP) response of human B cells to particulate antigens like TNP-polyacrylamide beads (TNP-PAA) is crucial for understanding B cell activation.
- The precise role of accessory cells, particularly monocytes, in this immune response has been a subject of investigation.
Purpose of the Study:
- To elucidate the role of monocytes in the anti-TNP antibody response of human B cells.
- To determine whether monocytes function as antigen-presenting cells in this system and to identify the mechanisms by which they support B cell activation.
Main Methods:
- Human B cells were cultured with TNP-PAA beads after depletion of adherent cells.
- Monocytes were added back at varying concentrations, or supernatants from activated monocytes were used.
- Studies included antigen-pulsed monocyte assays, allogeneic monocyte experiments, and the use of HLA-DR-negative K562 cells.
- T-cell involvement was assessed using B-enriched lymphocytes.
Main Results:
- The anti-TNP response was abolished by adherent cell depletion and restored by adding monocytes, with an optimal concentration of 3%.
- Supernatants from muramyl dipeptide (MDP)-activated monocytes, as well as partially purified interleukin-1 (IL-1), could restore the response.
- Evidence suggested monocytes do not act as antigen-presenting cells: antigen-pulsed monocytes failed to induce responses, allogeneic monocytes were effective, and HLA-DR-negative K562 cells could substitute for monocytes.
- Monocyte supernatants did not replace T cells, indicating T cells are directly involved in B-cell activation.
Conclusions:
- Monocytes are essential for the anti-TNP response of human B cells to TNP-PAA, but they do not function as classical antigen-presenting cells for this particulate antigen.
- Monocytes likely provide soluble factors, such as IL-1, that support B cell activation, working in conjunction with T cells.