The serum amyloid A stimulating factor (SAASF) in the hamster.

The acute phase SAA response was studied in hamsters. An SAA-stimulating factor (SAASF) was detected in the early acute phase blood plasma of hamsters which were subcutaneously injected with casein-LPS. The latter is routinely used in our laboratory for amyloid induction in hamsters. Acute (4 h) inflammatory exudates (greater than 80 per cent polymorphonuclear leukocytes) were produced by intraperitoneal injection with either casein-LPS, latex or Freund's incomplete adjuvant. Chronic inflammatory exudate macrophages (greater than 98 per cent) were elicited by intraperitoneal injection with Bacillus Calmette Guérin (BCG). Cells were stimulated in vitro with latex. SAASF was detected in the supernates and lysates of the acute exudate cells but not in those of the chronic peritoneal exudate macrophages. Lymphocyte activating factor (LAF), however, was evidently present in the latter samples, indicating that SAASF and LAF (IL-1) are functionally different substances in hamsters.