Lymphocyte characteristics and function in paroxysmal nocturnal haemoglobinuria

Area of Science:

• Immunology
• Hematology

Background:

• Paroxysmal nocturnal haemoglobinuria (PNH) is associated with immunological dysfunction.
• The underlying cause of this dysfunction in PNH patients remains unclear, with possibilities including lymphocyte defects or T-cell subset imbalances.

Purpose of the Study:

• To investigate the immunological dysfunction observed in patients with PNH.
• To determine if PNH characteristics directly affect lymphocytes or if an imbalance in T-cell subsets is responsible.

Main Methods:

• Studied six PNH patients using lymphocyte assays.
• Assessed PNH characteristics by exposing Indium111-oxine labeled lymphocytes to serum and acidified serum.
• Defined T-cell subsets (OKT3, OKT4, OKT8) and monocytes (OKM1) using monoclonal antibodies.
• Evaluated concanavalin-A suppressor cell activity.

Main Results:

• No complement-mediated lymphocyte lysis was demonstrated in PNH patients when exposed to acidified sera.
• A decreased proportion of total T-cells (OKT3) was observed in two patients.
• A significantly reduced ratio of helper T-cells (OKT4) to suppressor/cytotoxic T-cells (OKT8) was found in the group.
• No clear correlation existed between concanavalin-A suppressor cell activity and the OKT4/OKT8 ratio.
• Decreased monocyte counts (OKM1) were noted.

Conclusions:

• PNH characteristics do not appear to directly damage lymphocytes via complement.
• Immunological dysregulation in PNH is likely due to an imbalance in T-cell subsets.
• Reduced monocyte numbers may also contribute to the observed immune defects in PNH.