Abnormal CD4:CD8 ratios and delayed germinal center reconstitution in lymph nodes of human graft recipients with graft-versus-host disease (GVHD): an immunohistological study.

We searched for evidence that immunodeficiency in graft-versus-host disease (GVHD) is in part due to alloimmune damage to lymph nodes. We used immunoperoxidase techniques to stain T-cell subsets, pan-B cells, and follicular dendritic reticular cells (FDRC) in frozen sections of lymph nodes from 80 marrow graft recipients (56 with GVHD, 11 autografts, and 13 allografts without GVHD). We found that 46% of the GVHD patients had reversed CD4:CD8 ratios and only 13% of non-GVHD patients had such disturbed ratios (p = 0.006). Pan-B (CD22) cell labeling was present in the follicular regions of 73% of patients without GVHD and only 53% of patients with GVHD (p = 0.05). Focal FDRC staining was geographically concordant with clusters of B cells in 88% of cases (p less than 10(-7)). These data confirm that disturbed intranodal CD4:CD8 ratios are present more frequently in GVHD patients than in non-GVHD patients or in autografted patients. They suggest more delayed follicular B-cell reconstitution in GVHD patients. They show an extremely tight association of FDRC with clusters of B cells in the recovering lymph node, as in the developing fetal node. We hypothesize that the lack of follicular dendritic cells may contribute to dysfunctional B-cell maturation by ablating orderly antigen presentation and clonal expansion in the lymph node cortex.

Rapid methenamine silver stain for Pneumocystis and fungi.

A rapid modification of the methenamine silver stain for Pneumocystis carinii and fungi employs heat alone to accelerate the silver reduction step and is suitable for both sections and smears.