Enhancement of lymphocyte response to PHA by lysosomal enzymes from polymorphonuclear leukocytes of RA joint fluid. I. Biological effect on T lymphocyte function
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Abstract:
The effect of polymorphonuclear leukocyte (PMN) granule lysates obtained from joint fluid of RA on the in vitro DNA synthesis of PHA-stimulated autologous lymphocytes from joint fluid was studied. Lymphocytes were cultured for 3 days with or without PMN lysates in 2 ml of RPMI-1640 supplemented with 10% heat-inactivated fetal calf serum (FCS). The lymphocytes were stimulated with phytohemagglutinin (PHA-M). The DNA synthesis was measured by counting the [3H]thymidine incorporation. Lymphocytes from RA joint fluid stimulated with PHA-M showed 19,466+/-987 cpm (mean+/-SE) per 10(6) cells in the absence of PMN lysates. Upon addition PMN lysates to the PHA-stimulated lymphocytes, the maximum in vitro DNA synthesis increased to 44,877+/-1338 cpm. The enhancing effect of PMN lysates was abolished by plasma inhibitors or by passage through a column of protease inhibitor (Trasylol). It was concluded, therefore, that the enhancing effect of PMN lysates on PHA-stimulated lymphocytes may be associated with lysosomal proteases. Based on experiments using separated T and B lymphocytes, the enhancing effect of PMN lysates was considered to result from the activation of T lymphocytes. The results obtained in the present study suggest an important role for lysosomal proteases in the perpetuation of rheumatoid synovitis.
Insights
Lysosomal proteases from rheumatoid arthritis (RA) joint fluid enhance DNA synthesis in T lymphocytes. This suggests proteases may perpetuate inflammation in RA synovitis.
Area of Science:
- Immunology
- Biochemistry
- Rheumatology
Background:
- Rheumatoid arthritis (RA) is characterized by chronic joint inflammation.
- Polymorphonuclear leukocytes (PMNs) are abundant in RA joint fluid and release granule contents.
- The role of PMN granule components in modulating lymphocyte activity in RA is not fully understood.
Purpose of the Study:
- To investigate the effect of PMN granule lysates from RA joint fluid on the DNA synthesis of autologous lymphocytes.
- To identify the components within PMN lysates responsible for modulating lymphocyte activity.
Main Methods:
- Lymphocytes were isolated from RA joint fluid.
- Lymphocytes were cultured with or without PMN granule lysates and stimulated with phytohemagglutinin (PHA-M).
- DNA synthesis was quantified by [3H]thymidine incorporation.
Main Results:
- PMN granule lysates significantly increased DNA synthesis in PHA-stimulated lymphocytes (from 19,466+/-987 to 44,877+/-1338 cpm).
- The enhancing effect was abolished by plasma inhibitors and a protease inhibitor (Trasylol).
- Experiments with separated T and B lymphocytes indicated the effect resulted from T lymphocyte activation.
Conclusions:
- The enhancing effect of PMN lysates on lymphocyte DNA synthesis is mediated by lysosomal proteases.
- These proteases likely activate T lymphocytes, contributing to the perpetuation of inflammation in rheumatoid synovitis.