Formation of different abzymes in autoimmune-prone MRL-lpr/lpr mice is associated with changes in colony formation of haematopoietic progenitors

Abstract

It was shown that IgGs from the sera of 2-7-month-old control non-autoimmune (CBA x C57BL)F1 and BALB/c mice and 2-3-month-old autoimmune prone MRL-lpr/lpr mice (conditionally healthy mice) are catalytically inactive. During spontaneous development of deep systemic lupus erythematosus (SLE)-like pathology a specific reorganization of immune system of these mice leads to conditions associated with a production of IgGs hydrolyzing DNA, ATP and polysaccharides with low catalytic activities (conditionally pre-diseased mice).A significant increase in DNase, ATPase and amylase IgG relative activities associated with a transition from pre-diseased to deep diseased mice is correlated with additional changes in differentiation and proliferation of mice bone marrow haematopoietic stem cells (HSCs) and lymphocyte proliferation in different organs. The highest increase in all abzyme activities was found in mice immunized with DNA, which in comparison with pre-diseased and diseased mice are characterized by a different profile of HSC differentiation and by a suppression of cell apoptosis. Abzyme activities in the serum of pregnant females were comparable with those for pre-diseased mice, but the profile of HSC differentiation and cell apoptosis levels in pregnant and pre-diseased mice were quite different. Right after the beginning of lactation (4 days after delivery) and in a late time of lactation (14 days after delivery) there was an observed increase in cell apoptosis and two different stages of significant change in the HSC differentiation profiles; the first stage was accompanied with a significant increase and the second with a remarkable decrease in abzyme activities. Overall, all mouse groups investigated are characterized by a specific relationship between abzyme activities, HSC differentiation profiles, levels of lymphocyte proliferation, and cell apoptosis in different organs. From our point of view, the appearance of ATPase, DNase activities may be considered the earliest statistically significant marker of mouse spontaneous SLE and a further significant increase in their activities correlates with the appearance of SLE visible markers and with an increase in concentrations of anti-DNA Abs and urine protein. However, development of autoimmune (AI)-reactions and the increase in the sera anti-DNA antibodies (Abs) and in the abzyme activities in pregnant and lactating mice do not associate with SLE visible markers and proteinuria. The possible differences in immune system reorganizations during pre-disease, disease, pregnancy and lactation leading to production of different auto-antibodies and abzymes are discussed.

1

DNase activities of catalytic IgGs from different mice in the cleavage of supercoiled (sc) pBluescript DNA: lanes 1–11 correspond to 0.1 mg/ml IgGs from 11 different mouse sera incubated for 2 hrs at 30 °C; lane 12, DNA incubated with Abs from the serum of a healthy mouse; lane 13, DNA incubated alone.

2

Analysis of ATPase (A) and amylase (B) activities of purified IgG by thin-layer chromatography on PEI cellulose (A) and on Kieselgel plates (B) and autoradiography. (A) Before the chromatography, standard reaction mixtures containing 0.1 mg/ml IgGs and 0.2 mM [γ-³²P]ATP were incubated at 30°C for 2 hrs: lanes 1–6 correspond to IgGs from 6 different mice. (B) Before the chromatography, standard reaction mixtures containing 0.1 mg/ml IgGs and 0.15 mM MHO were incubated at 30°C for 12 hrs: lanes 2–11 correspond to IgGs from 10 different mice, lane 1, the substrate incubated alone.