Polymorphonuclear leucocyte fluorescence and cryoglobulin phagocytosis in systemic lupus erythematosus

Area of Science:

• Immunology
• Rheumatology

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune complex deposition.
• Cryoglobulins, immune complexes that precipitate in the cold, are found in some SLE patients.
• The role of cryoglobulins in SLE pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the interaction between peripheral blood polymorphonuclear leucocytes (PMN) and cryoglobulins in SLE patients.
• To determine if cryoglobulins are phagocytosed by PMN and if rheumatoid factor plays a role.

Main Methods:

• Peripheral blood PMN and cryoglobulins were isolated from SLE patients.
• Normal donor PMN were incubated with SLE patient sera and cryoglobulins.
• Fluorescent microscopy was used to detect inclusions within PMN.

Main Results:

• Fluorescent inclusions were observed in PMN after incubation with SLE patient cryoglobulins.
• Phagocytosis of cryoglobulins by PMN was confirmed.
• High anti-IgG activity was found in phagocytosed cryoglobulins, indicating the role of rheumatoid factor.

Conclusions:

• Phagocytosis of cryoglobulins by PMN occurs in SLE.
• Rheumatoid factor is important for the phagocytosis of immune complexes, including cryoglobulins.
• These findings support the concept that cryoglobulins are a subpopulation of immune complexes involved in SLE.