Immunohistochemical expression of perforin in adult systemic lupus erythematosus associated macrophage activation syndrome: Clinicohematological correlation and literature review.

Objective: To study the bone marrow (BM) immunohistomorphological characteristics in adult systemic lupus erythematosus (SLE) associated macrophage activation syndrome (SLE-MAS).

Materials And Methods: Immunohistochemical (IHC) expression of CD3, CD8, perforin (PFN), and CD163 was studied on BM trephine biopsies from 30 cytopenic adult SLE cases (male: female = 1:5, age; 24 years, range; 19-32) and compared them with ten age matched controls. Clinicopathological parameters were compared among the cases likely (L) or unlikely (U) to have MAS using probability scoring criteria. The best cut off laboratory parameters to discriminate between the two were obtained through receiver operator curve (ROC) analysis.

Results: MAS occurred in 12/30 (40%) cases and was more commonly associated with prior immunosuppressive therapy ( = .07), ≥ 3 system involvement ( = .09), lower fibrinogen ( < .01), increased triglyceride ( = .002), increased BM hemophagocytosis ( = .002), and higher MAS score [185 (176-203) vs. 105 (77-119), < .01] than MAS-U subgroup. Although PFN+CD8+ T lymphocytes significantly decreased among cases than controls ( < .05), it was comparable between MAS-L and MAS-U subgroups. Fibrinogen (< 2.4 g/L, AUC; 0.93, < .01), hemophagocytosis score (> 1.5, AUC; 0.71, = .03), and an MAS probability score of ≥ 164 (AUC; 1, < .01) discriminated MAS from those without MAS.

Conclusion: We noted a decrease in perforin mediated CD8 + T cell cytotoxicity in SLE. Immunohistochemical demonstration of the same along with histiocytic hemophagocytosis on BM biopsy may be useful adjunct in early diagnosis and management of MAS in SLE.