CD19+ MM PBMC Include a CD34+ Subset
| Tissue (no. samples) . | % CD34 on Small CD19+ . | % CD34 on Large CD19+ . |
|---|---|---|
| PBMC | ||
| MM untreated (11) | 5 ± 3 | 69 ± 10 |
| MM treated (39) | 25 ± 43-151 | 86 ± 4 |
| MM off Tr (26) | 23 ± 6‡ | 88 ± 4‡ |
| Normal (13) | 5 ± 2 | NA |
| MM BM plasma cells3-150 (11) | NA | 11 ± 2 |
| Tissue (no. samples) . | % CD34 on Small CD19+ . | % CD34 on Large CD19+ . |
|---|---|---|
| PBMC | ||
| MM untreated (11) | 5 ± 3 | 69 ± 10 |
| MM treated (39) | 25 ± 43-151 | 86 ± 4 |
| MM off Tr (26) | 23 ± 6‡ | 88 ± 4‡ |
| Normal (13) | 5 ± 2 | NA |
| MM BM plasma cells3-150 (11) | NA | 11 ± 2 |
PBMC from 61 myeloma patients were stained in direct/indirect or double direct IF, as for Fig 3. Some patients were analyzed at several time points and thus appear in more than one of the above categories. Using HPCA-1, the majority of B cells had a density of staining for CD34 that was 250 to 800 channels above the isotype matched control on a 1,024-log scale. Small B cells were defined as those with low forward and side scatter, and large B cells as those with a high side scatter and usually high forward scatter.7 On average there were 12% to 15% small and 14% to 26% large B in PBMC of myeloma patients.7
These cells were defined by their high expression of CD38 and cIg, relatively low expression of CD19, and the expression of CD45R0 by most. Their number corresponded closely with the number of BM plasma cells identified morphologically on cytospin slides.
P = .0002 and ‡P < .04 compared with untreated patients. Untreated small MM B cells were not significantly different from normal B cells. NA, not applicable; normal B PBMC are small resting cells.