Modification of thymo-dependent and thymo-independent antibody responses during non-specific acute inflammation.

An acute non-immunological inflammatory reaction, induced in mice by injecting intrapleurally a non-bacterial, non-antigenic and endotoxin-free irritant (40,000 molecular weight dextran or monoclinic dihydrated calcium pyrophosphate microcrystals), provoked an increase of antibody responses to thymus-dependent SRBC or thymus-independent TNP-LPS or DNP-Ficoll when the phlogistic stimulus was applied before immunisation. The increase in the number of IgM plaque-forming cells per spleen was obtained for different time intervals between the induction of the inflammatory stimulus and the antigen administration according to the type of irritant and the antigen used. However, no stimulation could be observed when this time interval was greater than three days. No stimulation of the antibody response to SRBC was observed when the irritant was applied one to three days after the antigen. The (stimulatory) effect could not be entirely related to a polyclonal activation as an augmentation in the production of antibody against non-cross-reactive antigen could only be seen four days after the onset of the inflammatory process, when the specific antibody response was not maximal. These observations indicate that an acute non-immunological inflammatory reaction lasting for 48 h can affect the immune reactivity of the host, even after the inflammatory process has disappeared.