Two hundred and twenty four hospitalized children in Baghdad aged between 1 month and 10 years were examined for Streptococcal infections. Thirty four percent of the throat and saliva specimens were positive for β-hemolytic streptococci. Males were more susceptible to infection with group A streptococci than females. Streptococcus of group A was isolated from 39.5% of the positive cases while group G was 47.4%. The etiological significance of the latter group in tonsillitis and otitis media is to be further investigated. Ninety six percent of the isolated streptococci were T typable and 13.3% of the strains were M typable. A high frequency of type T-11 was found in streptococcal infections. T type 3875 was found to be a new provisional type. All isolates were M untypable, and antiopacity factor negative except for two isolates of T type 4 which were positive in both typings.

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Congenitally athymic BALB/cA nu/nu mice were employed to elucidate the role of the thymus in experimental Mycoplasma pulmonis strain m53 infection, and nu/+ mice were used for comparison. Chronic polyarthritis was frequently produced in both of nu/nu and nu/+ mice by intravenous injection of the organisms. Macroscopically, nu/nu mice developed severer arthritis and a much lower grade of resolution than nu/+ mice. Periarticular abscess, conjunctivitis, and emaciation were observed in some of the nu/nu mice, but not in the nu/+ mice. Mycoplasmas were isolated from joints and other tissues (including periarticular abscesses and eyelids) of infected nu/nu mice at higher frequencies as well as in greater quantities, and did not show any elimination trends for at least 20 weeks after inoculation. However, in nu/+ mice, mycoplasmas were almost exclusively located in joints, and distribution of organisms to the other organs disappeared soon after the infection. Increases in complement-fixing antibody titers were not related to the inhibition of mycoplasmal spread. Thymus-dependent functions that may in some way prevent growth and spread of mycoplasmas in mice are discussed.

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In vitro disassembly of tobacco mosaic virus (TMV) virions occurred in the presence of both polyornithine and a lipid fraction isolated from tobacco leaf membrane. The latter could be replaced by lecithine. Disassembly of 10 μg of TMV virions was attained in the presence of a 500-mg leaf equivalent of membrane lipid and 20 μg of polyornithine in 1 ml of 0.01 M Tris-HCl buffer, pH 7.4 at 30 C. Similarity and dissimilarity between the in vitro disassembly and the in vivo uncoating mechanisms are discussed.

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We isolated fairly stable lysogenic-like bacteria from a lysogenic state established between an amber mutant for the maturation protein gene of RNA phage Qβ (Qβam205) and its nonpermissive host BE110. These bacteria contained few mature phages intracellularly (less than 10^-3 plaque forming unit per cell), continued to grow with a potentiality to produce Qβam205 spontaneously, and showed an immunity-like response against homologous phage infection. These characteristics were maintained by growth in liquid medium containing anti-Qβ serum. We designated these cells as pseudolysogenic bacteria. The relative amounts of RNA genomes in these pseudolysogenic cells (about 10² infectious RNA strands per cell) indicated that the RNA genomes could replicate in nonpermissive cells and be distributed in daughter cells synchronizing well with cell division.

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Adenovirus type 12 (Ad12) -transformed mouse cells were examined for their susceptibility to cell-mediated immunity in vitro, with respect to the activity of the virus-specific surface (S) antigen in the cells. A transformed cell line, C57ATl, was established from embryonic cells of C57BL/6 mice by Ad12 infection. In fluorescent antibody tests, the transformed cells were positive for the S antigen when the cells were maintained as cultures, whereas when the cells were grown as tumors in animals they became negative for the antigen (referred to as S (+) and S (-) cells, respectively). These S (+) and S (-) cells were subjected to the ⁵¹Cr-release test for cell lysis by immune spleen cells (ISC) raised in syngeneic mice by Ad12 infection. When the S (+) cells at various passage levels were exposed to ISC, all of them were lysed extensively and to a similar extent irrespective of their passage history. In contrast, the S (-) cells were consistently refractory to the action of ISC. In addition, the cytotoxic action of ISC was markedly impeded by pretreating the S (+) cells with antiserum to the S antigen, or the ISC with anti-Thy-1, 2 serum plus complement. Taken these findings together, the S (+) cells were assumed to be injured by ISC through direct interaction of the S antigen with T-lymphocytes.

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³H-Thymidine uptake of thymocytes from LPS-responder Balb/c mice in the presence of a submitogenic dose (0.5 μg/ml) of con A in vitro was significantly enhanced by adding LPS (0.1 to 2.5 μg/ml), while the uptake of thymocytes from LPS-nonresponder C3H/HeJ was not enhanced by LPS. However, “endotoxin soups, ” which were prepared from the supernatants of LPS-responder murine spleen cell cultures in the presence of LPS, clearly increased the incorporation of ³H-thymidine into C3H/HeJ thymocytes in the presence of this small amount of con A.The soup prepared from C3H/HeJ spleen cell cultures did not show any synergisti ceffect with con A. Even if the major histocompatibility between soup-producer-cells and responder cells to con A was different, the soups were still effective. The active substance in the “endotoxin soups” was eluted through a Sepharose CL-4B column, and its molecular size was estimated to be about 20, 000 daltons. The activity of the soups was destroyed by heating at 70 C for 30 min or at 80 C for 10 min. Digestion with trypsin destroyed the activity of the soups, but digestion with DNase or RNase did not. The role of the active substance in the soups in synergy with con A and its relation to the synergistic effect of con A and LPS are discussed.

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Helper T cell activities specific for purified protein derivative (PPD) generated by immunization with Mycobacterium tuberculosis (Tbc) or PPD were investigated concerning adoptive IgE and IgG antibody responses. It is interesting that preferential triggering activity of IgG antibody response was observed when PPD-reactive cells from mice immunized with Tbc were used as a helper cell source. The selective triggering of IgG B cells by Tbc-primed cells was consistently observed using DNP-primed B cell populations from mice immunized with DNP-carrier conjugate in either ICFA or alum. T cell dependency of helper activity was demonstrated by the fact that treatment of Tbc-primed cells with anti-Thy 1 antiserum plus complement abolished their helper activity. We also demonstrated that purified T cell populations selectively triggered IgG B cells.
Selective triggering of IgG B lymphocytes by Tbc-primed T cells may not be due to the influence of suppressor T cells supposedly present in Tbc-primed cells since this selectivity was not affected by X-irradiation of Tbc-primed T cell populations which may inactivate suppressor T cells. Furthermore, passive transfer of Tbc-primed cells into normal recipient mice, the condition which may detect the suppressor T cell effect much more sensitively in IgE production, or preimmunization with Tbc 2 weeks before, did not suppress primary anti-DNP IgE antibody response to DNP-PPD. Thus, the observations presented here are favorable to the concept of the presence of IgG class-specific helper T lymphocytes.
Furthermore, PPD-reactive T cells from mice immunized with PPD itself exerted their helper function for triggering B cells of both IgE and IgG classes. This may also indicate that some of the components associated with Tbc other than PPD might negatively affect the development of PPD-reactive helper T cells specific to the IgE class.
The generation of such IgG-specific T cell activity in the presence of Tbc will be discussed in the light of the T cell population involved in the regulation of antibody responses of different immunoglobulin classes.

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