A series of immune function and host resistance parameters were examined in female B6C3F1 mice following a 21-day (6 hr/day) inhalation exposure to 15 ppm of
formaldehyde (HCHO). Immune parameters examined included
delayed hypersensitivity to
keyhole limpet hemocyanin, antibody plaque-forming cell response to sheep erythrocytes (T-lymphocyte-dependent
antigen) and
TNP-Ficoll (T-lymphocyte-independent
antigen), lymphoid organ weights and histopathology, routine hematology, bone marrow cellularity and CFU progenitor cell enumeration, lymphocyte subpopulation quantitation by cell surface markers,
mitogen-induced lymphocyte blastogenesis, macrophage function parameters, and host resistance to challenge with the bacterium Listeria monocytogenes and transplantable
tumor cells. Lymphoid organ weight, bone marrow cellularity, and hematology parameters were unchanged in HCHO exposed mice. Similarly, the percentage of T and B lymphocytes and their proliferative responses to
mitogens were not significantly altered.
Antibody (IgM) plaque-forming cell response following
antigen challenge was unchanged. Macrophage function was normal although some evidence of enhanced H2O2 production associated with elevated bactericidal activity was observed in resident macrophages. Resistance to challenge with the bacteria Listeria monocytogenes was significantly enhanced, while resistance to
tumor challenge remained unchanged. No evidence of immunosuppression following short-term exposure to HCHO was observed.