Signal transduction by B and T cells early after bone marrow transplantation: B cell calcium flux responses are intact whereas lack of CD4 cells accounts for impaired T cell responses.
We previously found that intracellular ionized calcium ([Ca2+]i) flux responses after anti-CD3 crosslinking of CD3/TCR on T cells from allogeneic and autologous bone marrow transplant (BMT) recipients were impaired, Yamagami et al. J Clin Invest 1990; 86: 1347-1351. In contrast to the earlier study, this study focuses on identifying the T cell subset(s) responsible for the defects and determining if B cell responses are defective in BMT recipients early after BMT. In 37 recipients after anti-CD3 stimulation of PBL, a mean of 25.9% responding T cells was observed. This was significantly lower than the mean of 43.6% responding T cells in PBL from 21 normals (P < 0.001). The proportion of responding T cells in PBL (T PBL) increased in the recipients with time after BMT. By 6 months after BMT, the mean percent of responding T PBL approached the normal range. On the other hand, a mean of 8.1% responding B cells in anti-IgM crosslinked PBL from 24 recipients was not different from the mean of 7.4% responding B cells in anti-IgM crosslinked PBL from 16 normals (P = 0.6). Four color flow cytometry was used to identify subpopulations of lymphocytes. Enriched B cells were tested by gating out CD3+ and CD56+ cells to confirm the results of unfractionated PBL. In 8 recipients, the mean percent responding B cells was 36.6% and was not different from 6 normals (mean = 41.0%).(ABSTRACT TRUNCATED AT 250 WORDS)