Addition of heme (X factor) and pyridine nucleotide (V factor) to the medium permits rapid growth of Haemophilus influenzae, with evolution of easily detectable amounts of "4CO2. Radiometric media containing X and V factor should be used when evaluating clinical specimens which might contain Haemophilus species.

Streptococcal and salmonella antisera inhibited carbohydrate metabolism for groups A, B, C, and D streptococci and group E salmonella, as measured by the formation of [14C dioxide from [14C glucose metabolism. For salmonella, the inhibition was type specific since group E salmonella were inhibited only by salmonella E antisera and not by anti-salmonella A or C1. For streptococci, quantitative differences were demonstrated, but major cross-reactivity was observed. At high concentrations, the antisera were bactericidal; at more dilute concentrations, for both salmonella and streptococci, carbohydrate metabolism was suppressed, but subculture on chocolate agar showed abundant growth. Cross-reacting antibodies could be absorbed by incubation with either antigen, e.g., streptococcal antisera versus heat-killed salmonella. The results suggest that the radiometric technique can be more sensitive than either capillary flocculation or visual detection of bacterial growth for detecting the inhibition of streptococci and salmonella by specific antibodies. The use of specific antisera may prove useful for bacterial species identification in an automated system for detection of bacterial growth.

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Recent evidence indicates that interleukin 2 (IL 2), formerly thought to serve as growth factor exclusively for activated T cells, is directly involved in human B cell differentiation. We have investigated the role of IL 2 and IL 2 receptors (as defined by monoclonal anti-Tac antibody) in the phorbol ester-induced in vitro maturation of leukemic B cells from patients with chronic lymphocytic leukemia (CLL). Peripheral blood lymphocytes from B cells from CLL patients with high (greater than 10(5)/microliters) white blood cell counts were depleted of residual T lymphocytes and low-density cells (primarily macrophages) by consecutive steps of E rosetting, complement-mediated lysis of OKT3+ and OKT4+ cells, and Percoll density gradient centrifugation. No OKT3+ T cells were detectable in these cell populations before or after culture. When incubated for 3 days with phorbol ester plus recombinant human IL 2 (rIL 2), 12 to 57% of highly purified B cells from four of five tested patients expressed Tac antigen. Both phorbol ester and rIL 2 were required for maximal Tac antigen expression. Functional studies revealed that phorbol ester-activated (but not resting) CLL B cells responded to rIL 2 with [3H]thymidine incorporation and with enhanced secretion of IgM. Tac+ B cells were isolated in two cases on a fluorescence-activated cell sorter. In one patient, stimulation of Tac+ B cells with rIL 2 resulted in enhanced [3H]thymidine incorporation but no change in IgM secretion, as compared with Tac- B cells; in the second patient, stimulation of Tac+ B cells with rIL 2 did not result in [3H]thymidine uptake, but did result in significant IgM secretion. These findings indicate that certain leukemic B lymphocytes can be induced to express IL 2 receptors and respond to IL 2. The use of resting clonal B cell populations arrested at distinct stages of differentiation may help to better define the stage(s) at which IL 2 acts directly on B cells to induce proliferation and/or terminal differentiation.