Scanning electron microscopy of human lymphocyte-sheep erythrocyte rosettes

Area of Science:

• Immunology
• Cell Biology
• Microscopy

Background:

• Human lymphocytes, crucial for adaptive immunity, are broadly classified as T cells and B cells.
• Distinguishing between T and B lymphocytes is essential for understanding immune responses and diagnosing immune disorders.
• Scanning electron microscopy (SEM) offers high-resolution surface imaging, potentially revealing morphological differences between lymphocyte subsets.

Purpose of the Study:

• To investigate the surface morphology of human T and B lymphocytes using SEM.
• To determine if SEM can reliably differentiate between T and B lymphocytes based on surface characteristics, particularly after rosetting.
• To assess the impact of rosetting with sheep red blood cells (SRBC) on lymphocyte surface morphology.

Main Methods:

• Human peripheral blood lymphocytes (PBL), thymic cells, and cultured T and B cells were analyzed using SEM.
• Cells were prepared for SEM using critical point drying.
• Rosette formation was induced using SRBC (for T cells, E-rosettes) and antibody-coated SRBC (for B cells, EAC-rosettes).

Main Results:

• Sheep red blood cells (SRBC) frequently transformed into sphero-echinocytes after rosetting.
• Most rosetting T lymphocytes exhibited smooth surfaces, while a significant portion showed intermediate to villous surfaces.
• The majority of rosetting B lymphocytes displayed multiple microvilli, with a smaller percentage having intermediate or smooth surfaces.
• Surface alterations, including increased villousness, were observed in some T cells after rosetting.
• While SEM revealed distinct surface architectures for most B and T cells, approximately 20% of rosetting cells showed similar intermediate microvilli, hindering clear distinction without immunological markers.

Conclusions:

• SEM can distinguish between human T and B lymphocytes based on surface morphology in many cases.
• Rosetting can induce surface changes in T lymphocytes, increasing their villousness.
• A subset of rosetting B and T lymphocytes exhibit similar surface features, necessitating complementary immunologic identification for accurate classification.