The roles of IgG and secretory IgA in the protection of the respiratory tract (RT) against influenza infection remain unclear. Passive immunization with Ab doses resulting in serum IgG anti-influenza virus Ab titers far in excess of those observed in immune mice has compounded the problem. We compared the effects of i.v. anti-influenza virus IgG and i.v. anti-influenza virus polymeric IgA (pIgA) mAb administered in amounts designed to replicate murine convalescent serum or nasal Ab titers, respectively. A serum anti-influenza virus IgG titer 2.5 times the normal convalescent serum anti-influenza virus IgG titer was required for detectible Ab transudation into nasal secretions, and a serum IgG titer 7 times normal was needed to lower nasal viral shedding by 98%. Anti-influenza virus pIgA at a nasal Ab titer comparable to that seen in convalescent mice eliminated nasal viral shedding. The RT of influenza-infected pIgA- or IgG-protected mice were studied by scanning electron microscopy. Only pIgA was found to prevent virally induced pathology in the upper RT, suggesting that IgG did not prevent viral infection of the nose, but neutralized newly replicated virus after infection had been initiated. In contrast, IgG, but not pIgA, was found to prevent viral pathology in the murine lung. Our results help to resolve the controversy of IgA- vs IgG-mediated protection of the RT; both Abs are important, with plasma IgG Ab serving as the back-up for secretory IgA-mediated protection in the nasal compartment, and IgG being the dominant Ab in protection of the lung.

To investigate the role of CD8+ T lymphocytes in recovery from influenza pneumonia, we used transgenic mice either homozygous (-/-) or heterozygous (+/-) for beta 2-microglobulin (beta 2-M) gene disruption. These mice lack major histocompatibility complex-restricted class I (CD8+) T cells. We found that after challenge with a nonlethal influenza virus, the beta 2-M (-/-) mice had significantly delayed pulmonary viral clearance. Furthermore, after challenge with a more virulent influenza virus, the beta 2-M (-/-) mice had a significantly higher mortality rate than did control mice. Thus, CD8+ T cells are important in recovery from virulent influenza infections, but other host defense mechanisms can clear the respiratory tract of more benign infections.

Individuals who possess special abilities, skills, and knowledge relative to the group task have the potential to make important contributions to group performance. The degree to which this potential is realized depends on the behaviors of those persons. These behaviors are determined, in part, by the individual characteristics of group members (Mann, 1959;Bouchard, 1969) and in part by the particular assembly of persons (Rosenberg et al., 1955). The important question, however, is what kinds of behaviors influence performance in groups. In an earlier study (Shaw et al., 1979), an attempt was made to identify some of the behaviors of group members that are related to their own performance and to the performance of other group members. The results supported the hypothesis that giving information, ideas, and opinions to the group is positively correlated with the perception by others in the group that the member is facilitating group performance, whereas asking for information and opinions is positively related to objective measures of facilitation of group performance. AUTHORS' NOTE: We wish to express our deep appreciation to the University of Florida Medical and Dental Classes of 1981 and 1982. Without their approval and cooperation these studies would have been impossible. The project was partially supported under Contract SP20/77A by the National Fund for Medical Education.

At the present time mammalian antibodies have been demonstrated in at least three classes of serum proteins referred to as immunoglobulins. The hnmunoglobulin classes have been designated g~mma M, gamma G, and gamma A (1). Each of these proteins is composed of multiple polypeptide chains and the classes are distinguished primarily on the basis of differences of the heavier chains (2).The ability to produce humoral antibodies in response to antigenic stimulation appears to be limited to the vertebrate species (recently reviewed, see Reference 3). Results previously obtained have indicated that the elasmobranchs are phylogenetically among the most ancient vertebrates capable of undergoing an antibody response (4, 5). In order to gain some understanding of the nature of the immunoglobulins synthesized by elasmobranchs, studies were initiated with the lemon shark, Negaprion brevirostris. It was hoped, in light of the complexity and heterogeneity of mammalian immunoglobufins, that the shark immunoglobulin(s) would prove to be a simpler or a more homogeneous population of molecules.This report presents the results of studies with the lemon shark involving the production of antibodies to bovine serum albumin, the association of these antibodies with two molecular species of serum proteins, and the purification and characterization of these immunoglobulins. Results are also presented regarding the nature of shark proteins with electrophoretic mobilities comparable to gamma G immunoglobulin of mammals.